Language：Japanese   Publisher：The Society of Exploration Geophysicists of Japan  

S-wave shallow seismic reflection survey and two-dimensional electrical resistivity survey targeting depths less than 100 m were applied to the strike-slip fault. This study was conducted in the Go-mura fault zone and the Yamada fault zone where surface rupture occurred during the 1927 Kita Tango earthquake. For the interpretation of the two-dimensional electrical resistivity survey results, we carried out in situ measurement of the electrical resistivity on outcrops around the survey area. It was confirmed that there is 10 times contrast in the electrical resistivity between the fresh or weathering granite and the fracturing part or clay part of granite. At the study area in the Go-mura fault zone, discontinuity and deformation of the reflection surface from the S-wave shallow seismic reflection profile corresponds to the location and displacement sense of the active fault estimated by boring and trench survey. As the result of applying two-dimensional electrical resistivity survey, the low resistivity zone continuing from deep underground to shallow was recognized near the active fault trace on the ground. This low resistivity zone indicates the fracture zone of host rock with fluid supply from fault activity. At the study area in the Yamada fault zone, the similar survey results as in the study area of the Go-mura fault zone were obtained. Discontinuity and deformation of the reflection surface from the S-wave shallow seismic reflection profile corresponds to the location and displacement sense of the active fault. In addition, as the result of two-dimensional electrical resistivity survey, the low resistivity zone continuing from deep underground to shallow was recognized near the active fault trace on the ground. The low resistivity zone was confirmed to be continuous down to the depth of 300 m or deeper by comparing with CSAMT survey result. Two-dimensional electrical resistivity survey was carried out with multiple measurement lines at another study area where the stepping of the active fault trace on the ground has been inferred from the comparison of the strike of the Yamada fault zone. As a result, the low resistivity zone was distributed almost linearly underground, and it could be shown that the distribution of active faults might be different between the surface and the underground.

DOI： 10.3124/segj.75.1

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Publishing type：Part of collection (book)   Publisher：Springer Nature Singapore  

DOI： 10.1007/978-981-19-1150-7_18

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Publishing type：Part of collection (book)   Publisher：Springer Nature Singapore  

DOI： 10.1007/978-981-19-1150-7_7

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Language：Japanese   Publisher：The Association of Japanese Geographers  

DOI： 10.14866/ajg.2017s.0_100281

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The 2016 Kumamoto earthquake sequence was a rare event worldwide in that the surface ruptures associated with the largest foreshock (Mj 6.5) of 21:26 (JST), 14 April ruptured again during the mainshock (Mj 7.3) of 01:25 (JST), 16 April. The 14 April Mj 6.5 earthquake produced 6-km-long surface ruptures along the central portion of the Futagawa-Hinagu fault zone (FHFZ). The mainshock produced 31-km-long surface ruptures along the central to northeastern part of the FHFZ. Field observations and eyewitness accounts documented that the offsets of the ruptures associated with the 14 April foreshock became larger after the 16 April mainshock, suggesting that the same portion of the fault ruptured to the surface twice in the Kumamoto earthquake sequence. The 6-km-long surface ruptures associated with the largest foreshock are located near a geometric bend of the FHFZ characterized by ~50° change in strike. The epicenter of the mainshock is also located near the bend. These observations imply that the Kumamoto earthquake sequence was initiated due to a stress concentration on the bend of the FHFZ, and the mainshock was initiated approximately at the same place about 28 h after the largest foreshock. This foreshock/mainshock sequence of the Kumamoto earthquake is not successive events on the adjacent different fault zones, because the 6-km-long surface ruptures of the largest foreshock are part of the 31-km-long surface ruptures of the mainshock.[Figure not available: see fulltext.].

DOI： 10.1186/s40623-016-0547-5

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Nature  

We perform terrestrial laser scanning (TLS) to detect changes in surface morphology of a mud volcano in Murono, north-central Japan. The study site underwent significant deformation by a strong earthquake in 2011, and the surface deformation has continued in the following years. The point cloud datasets were obtained by TLS at three different times in 2011, 2013 and 2014. Those point clouds were aligned by cloud-based registration, which minimizes the closest point distance of point clouds of unchanged ground features, and the TLS-based point cloud data appear to be suitable for detecting centimeter-order deformations in the central domain of the mud volcano, as well as for measurements of topographic features including cracks of paved ground surface. The spatial patterns and accumulative amount of the vertical deformation during 2011-2014 captured by TLS correspond well with those previously reported based on point-based leveling surveys, supporting the validity of TLS survey.

DOI： 10.1186/s40623-016-0495-0

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This chapter examines damage maps produced at the time of a large-scale disaster and their roles. Materials for examination are our tsunami inundation area map prepared using posttsunami aerial photographs, and mapping results of the tsunami run-up heights measured using a digital elevation model afterward. Based on these examinations, we reveal the remarkable spatial variation in the range and height inundated by the tsunami, and discuss its scientific significance and lessons for disaster management.

DOI： 10.1016/B978-0-12-809862-2.00003-6

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Lanyu and Lutao Islands to the southeast of Taiwan are located in the northern extension of the Luzon Arc. Crustal deformation of these islands provides a key to understand the collision of the Luzon Arc against Taiwan. To clarify the style and the rate of vertical movement during the Holocene, uplifted coral reefs fringing these two islands were investigated. Living corals were also investigated for comparison with fossil corals. It was found that Isopora palifera lives dominantly in the upper slope of the present-day fringing coral reefs in Lanyu Island at an average depth of 101 ± 46 cm (one standard deviation) below mean sea level. Using I. palifera as an accurate indicator of paleo-sea levels, Holocene relative sea-level changes were reconstructed. Lanyu Island has been uplifted continuously at a rate of 2. 0 mm yr -1, at least during the late Holocene from 2,269 cal. yr BP to the present. Lutao Island has been uplifted at an average rate of 1. 2 mm yr -1, since at least 5,749 cal. yr BP, although it is unclear whether the uplift was continuous. The present observations, combined with the GPS displacement field and deep crustal structure, suggest that the continuous uplift is related to aseismic slip on the Longitudinal Valley Fault. © 2011 Springer-Verlag.

DOI： 10.1007/s00338-011-0783-x

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHINESE GEOSCIENCE UNION  

This paper reports on the trench log data covering the Chelungpu Fault preserved at the National Science Museum and 10 bore hole data across the fault. Trench log indicates the vertical offset of the 1999 displacement of terrace deposits is ca. 1.5 m and the presence of four branch faults cutting terrace deposits within 1.8 m width zone. Estimated height difference of bedrock surface based on bore hole data is more than 4.2 - 5.8 m, larger than the offset by the 1999 earthquake. These facts imply that at least one earthquake event occurred at this site before the 1999 earthquake. We also estimate the fault plane dips eastward at about 30 degrees based on the location and stratigraphy of one bore hole which penetrates the terrace gravel on the hanging wall through the bedrock.

DOI： 10.3319/TAO.2009.08.25.02(TT)

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This study aims at the recent activity and development of an active wrench fault, the Touhuanping Fault in northwestern Taiwan. Northwestern Taiwan has been proposed in a current situation between the mature to waning collision in terms of tectonic evolution. The main drainage in this area, the Chungkang River, flows close to the trace of the fault mentioned above. We examined various types of deformation of fluvial terraces along the Chungkang River as a key to understanding the nature and rate of the late Quaternary tectonics. The E-W trending Touhuanping Fault has long been mapped as a geological boundary fault, but its recent activity was suspected. Field survey revealed that its late Quaternary activity is recorded in the offset fluvial terraces. Our result shows dextral slip and vertical offset with upthrown side on the south, and activated at least twice since the emergence of terrace 4 (older terrace 3 with OSL date of ca. 80 ka). Total amount of offset recorded in the Touhuanping terrace sequence is 15 m for dextral and 10 m for vertical offset. Estimated recurrence time of earthquake rupture may be a few tens of thousand years. Uplift on the upthrown side of the Touhuanping Fault also resulted in the formation of drowned valleys which were graded to terrace 4. Other deformation features, such as back-tilting, westward warping, and a range-facing straight scarp, were also identified. A second-order anticline roughly parallel to the Touhuanping Fault is suggested to be the origin of the northward tilting on terrace 3; it could have resulted from a flower structure on the Touhuanping Fault at shallow depth. This may demonstrate that the buried segment of the Touhuanping Fault has also been active since 80 ka. In the northern study area, the westward warping at terrace 2 probably represents late Quaternary activity of another NE-SW trending Hsincheng Fault. © 2009 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.tecto.2009.04.034

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High-resolution seismic reflection profiles across coseismic fault scarps reactivated during the A.D. 1896 Rikuu earthquake along the eastern margin fault zone of the Yokote basin (EFZYB) in northeast Japan, correlated with borehole stratigraphy and geologic mapping, provide insights into its detailed kinematic history and structural evolution. In spite of along-strike variations of thrust geometries both at ground surface and at shallow depth, the EFZYB has commonly formed as forward breaking imbricate thrust systems. Near surface complexity of thrust geometries appears strongly affected by mechanical decoupling between layers within middle to late Miocene mudstone. Cross-section balancing across the Mahiru Mountains shows strong correlation of the millennial uplift rates with mountain topography but its weak correlation with the late Pleistocene uplift rates. Considering the thrust trajectories estimated by the balanced cross sections, the millennial dip-slip rate are consistent with the late Pleistocene dip-slip rate, suggesting that the EFZYB has accumulated strains at a constant rate since the onset of its fault activity. © 2009 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.tecto.2009.02.007

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The northern Fossa Magna (NFM) is a back-arc rift basin filled with thick Tertiary sediments, which show strong NW-SE shortening deformation. In the NFM, there exist two major active fault systems, the Itoigawa-Shizuoka Tectonic Line active fault system (ISTL) and the Western Nagano Basin active fault system (WNB), both of which have great potentials to cause destructive earthquakes. By reanalyzing five sets of refraction/wide-angle reflection data, we successfully obtained detailed and consistent models of the crustal structure in the NFM region. It was a very effective modeling procedure to incorporate vicinal seismic reflection data and geologic information. The geometries of the active faults in the NFM region were revealed. The ISTL is east dipping, and the WNB is northwest dipping. The Tertiary sedimentary layer (<4.0 km/sec) west and adjacent to the ISTL extends to a depth of 4-5 km. The basement rocks below the Central Uplift Belt (CUB) form a wedge structure, which suggests the westward movement of the CUB basement rocks. © 2004, The Seismological Society of Japan, Society of Geomagnetism and Earth, Planetary and Space Sciences, The Volcanological Society of Japan, The Geodetic Society of Japan, The Japanese Society for Planetary Sciences. All rights reserved.

DOI： 10.1186/BF03353353

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The northern Fossa Magna (NFM) basin is a Miocene rift system produced in the final stages of the opening of the Sea of Japan. It divides the major structure of Japan into two regions, with north-trending geological structures to the NE of the basin and EW trending structures to the west of the basin. The Itoigawa-Shizuoka Tectonic Line (ISTL) bounds the western part of the northern Fossa Magna and forms an active fault system that displays one of the largest slip rates (4-9 mm/year) in the Japanese islands. Deep seismic reflection and refraction/wide-angle reflection profiling were undertaken in 2002 across the northern part of ISTL in order to delineate structures in the crust, and the deep geometry of the active fault systems. The seismic images are interpreted based on the pattern of reflectors, the surface geology and velocities derived from refraction analysis. The 68-km-long seismic section suggests that the Miocene NFM basin was formed by an east dipping normal fault with a shallow flat segment to 6 km depth and a deeper ramp penetrating to 15 km depth. This low-angle normal fault originated as a comparatively shallow brittle/ductile detachment in a high thermal regime present in the Miocene. The NFM basin was filled by a thick (>6 km) accumulation of sediments. Shortening since the late Neogene is accommodated along NS to NE-SE trending thrust faults that previously accommodated extension and produce fault-related folds on their hanging wall. Based on our balanced geologic cross-section, the total amount of Miocene extension is ca. 42 km and the total amount of late Neogene to Quaternary shortening is ca. 23 km. © 2004 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.tecto.2004.07.004

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The slip-rates on the northern extent of Itoigawa-Shizuoka tectonic line (ISTL) are estimated based on seismic reflection profiles, drill core data and analysis of tectonic geomorphology. The ISTL is a major tectonic line that passes through the Honshu Island of Japan, and its northern and central segments form an active fault system characterized by high slip-rates. In the Kamishiro basin, near the northern end of the ISTL active fault system, the rate of net slip is estimated to be 4.4-5.4 m/kyr over the last 28 ka, with a vertical-separation-rate of 2.2-2.7 m/kyr. In the Omachi area, south of the Kamishiro basin, the Quaternary slip-rate is estimated to be at least 2.9 m/kyr based on the balanced cross-section derived from reflection profiles and surface geology. The dip angle of 30° determined from the Omachi seismic profile suggests a vertical-separation-rate of at least 1.5 m/kyr. Based on compiled evidence from the available geomorphological and paleo-seismological data, vertical-slip-rates of 1.0-2.9 m/kyr are inferred for the region between Hakuba and Toyoshina over the past 3 ka. The northern ISTL exhibits dip-slip-rate of at least 2.9 m/kyr, with a constant average slip-rate of 2.0-5.8 m/kyr since the Early Quaternary. A paleoseismological data and long-term slip-rate along the northern ISTL has potential for a large earthquake. Copyright © The Society of Geomagnetism and Earth, Planetary and Space Sciences (SGEPSS); The Seismological Society of Japan; The Volcanological Society of Japan; The Geodetic Society of Japan; The Japanese Society for Planetary Sciences.

DOI： 10.1186/BF03353357

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The Itoigawa-Shizuoka Tectonic Line (ISTL) in Central Japan is a fault zone with a very high slip rate during Pliocene-Quaternary time. Our seismic reflection and gravity surveys across the northern segment of the ISTL at Matsumoto have revealed its geometry to a depth of ∼5 km. The fault plane was found to be of fairly low angle, in spite of the surface geologic observations that late Quaternary movements on this fault zone are dominantly strike slip. Partitioning of slip is taking place between the East Boundary Fault (thrust) and the Gofukuji Fault (left-slip), which constitute the fault zone and are parallel to and a few km apart from each other. However, these two faults are found to merge down-dip at a depth as shallow as 1.5 km below the surface. The geometry of the ISTL is significantly discordant with the orientation of the maximum shear stress acting regionally on Central Japan, indicating that the fault plane is of very low strength. Copyright © The Society of Geomagnetism and Earth, Planetary and Space Sciences (SGEPSS); The Seismological Society of Japan; The Volcanological Society of Japan; The Geodetic Society of Japan; The Japanese Society for Planetary Sciences.

DOI： 10.1186/BF03353356

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The northern Fossa Magna (NMF) is a Miocene rift basin formed in the final stages of the opening of the Sea of Japan. The northern part of Itoigawa-Shizuoka Tectonic Line (ISTL) bounds the western part of the NMF and forms an active fault system that displays one of the largest slip rates in the Japanese islands. Reflection and refraction/wide-angle reflection profiling and earthquake observations by a dense array were undertaken across the northern part of ISTL in order to delineate structures in the crust, and deep geometry of the active fault systems. The ISTL active fault system at depth (ca. 2 km) shows east-dipping low-angle in Omachi and Matsumoto and is extended beneath the Central Uplift Zone and Komoro basin keeping the same dip-angle down to ca. 15 km. The upper part of the crust beneath the Central Uplift Zone is marked by the high Vp and high resistivity zone. Beneath the folded zone of the NMF, the middle to lower crust shows low Vp, low resistivity and more reflective features. The balanced geologic cross-section based on the reflection profiles suggests that the shortening deformation since the late Neogene was produced by the basin inversion of the Miocene low-angle normal fault. Copyright © The Society of Geomagnetism and Earth, Planetary and Space Sciences (SGEPSS); The Seismological Society of Japan; The Volcanological Society of Japan; The Geodetic Society of Japan; The Japanese Society for Planetary Sciences.

DOI： 10.1186/BF03353348

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Shaded-relief images created from digital elevation models (DEMs) are helpful in identifying faults in rugged mountains. Unlike airphoto interpretation, the method enhances lineaments by simulating topographic illumination under varied light directions. Interpretation of shaded-relief images of the Japanese Alps led to the discovery of a lineament unrelated to bedrock structure. Field surveys and analysis of large-scale maps and airphotos reveal the lineament to be a fault with high rates of vertical and lateral slip. The new fault is the southernmost segment of a known adjacent fault, and the rate and direction of its slip provide fresh insight into the late Quaternary history of the fault system. Because previous research mistook the fault scarp for a fluvial terrace scarp, discovery of the fault also changed the correlation of river terraces in the Northern Japanese Alps. The new corrections affect Pleistocene glacial chronology in the upstream area. © 2003 Elsevier Science Ltd. All rights reserved.

DOI： 10.1016/S0098-3004(03)00083-9

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Total pages：viii, 100p, 図版 [2] p   Language：Japanese

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Total pages：249p, 図版viiip   Language：Japanese

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Total pages：ix, 234p, 図版 [2] p   Language：Japanese

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Total pages：iv, 254p   Language：Japanese

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Language：Japanese   Publisher：京都大学防災研究所自然災害研究協議会  

能登半島北東部では，2020年12月頃から地震数の顕著な増加と局所的な非定常地殻変動が観測され，活発な地震活動が継続する中，2022年6月19日にマグニチュード5.4（最大震度6弱）の地震が発生した。この長期間継続する地震活動や地殻変動の原因及び2022年6月19日の地震による災害像を明らかにするため，令和4年度科学研究費（特別研究促進費）による総合調査により，地震観測，測地観測，電磁気観測，重力観測，温泉成分測定，活構造調査，強震観測を実施した。
主催：京都大学防災研究所自然災害研究協議会; 日程：令和5年9月25日（月）13時00分～16時40分（終了予定）; 場所：きはだホール（京都大学宇治キャンパス内）およびZoomによるハイブリッド開催
科学研究費補助金・特別研究促進費による突発災害調査研究令和4年度報告

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Language：Japanese   Publisher：東京 : 物理探査学会  

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Language：Japanese   Publisher：一般社団法人 日本教育心理学会  

DOI： 10.20587/pamjaep.65.0_68

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Language：Japanese   Publisher：The Association of Japanese Geographers  

DOI： 10.14866/ajg.2022s.0_189

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DOI： 10.14866/ajg.2022s.0_162

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DOI： 10.14866/ajg.2022s.0_191

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The topographic features such as marine terraces and coastal plains and their sediments have been used to study the crustal movement and tsunami history associated with the repeated earthquakes in the Nankai Trough. In order to extract valuable information on crustal movement and tsunamis through the analysis of these landforms and sediments, it is necessary to clarify the relationship between the landforms and strata formation and glacial sea-level change. We report the results of analysis of sediment cores obtained from the Kikugawa lowland in the eastern part of the Enshunada and discuss the formation process of the Kikugawa lowland.

DOI： 10.14866/ajg.2022s.0_158

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Language：Japanese   Publisher：Institute of Social Safety Science  

This study focuses on child-rearing care support for the people who suffered by floods. In case houses are affected by floods, people have to cleanup, dry and repair houses. People have to evacuate shelters or temporary houses until their own home repair finish. The change of living environment sometime causes difficulty in balancing works, household works and parenting works. The study analyzes child-rearing work balance focusing work allocation among family, government support and community support through case study of Mabi Town, Kurashiki City, Japan which suffered by the 2018 July heavy rain disaster. It tries to identify post-disaster parenting work balance problems and discusses how to balance those works.

DOI： 10.11314/jisss.39.315

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Language：Japanese   Publisher：Japan Society for Natural Disaster Science  

Recent heavy rain disasters in Japan showed the fact that although government issuedevacuation information, there were people who did not evacuate. This indicates that evacuationinformation based on science, which is institutionalized as a decision-making mechanismfor government, is not properly utilized by public. This study conducted surveys to residentsof Mabi Town, Kurashiki City, Japan, which was severely flooded due to the Western Japanheavy rain of July, 2018. The study tried to identify factors which triggered risk awarenessof residents comprehensively, and examined how those factors contributed to evacuationdecision-makings using "Evacuation Act Curve," the method adapted to the "Recovery Curve"surveys. As a result, the study revealed the fact that residents were tend to evacuate based onchanges in familiar environment rather than science-based information, which means thatdisaster information was still not considered as familiar information.

DOI： 10.24762/jndsj.39.4_439

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Language：Japanese   Publisher：The Association of Japanese Geographers  

<p>In the Okada district of Mabi-cho, Kurashiki City, which experienced the heavy rain disaster in western Japan in 2018, residents are trying to hand down the flood disaster experience so that they will never have a tragic experience again. In that activity, disaster prevention and mitigation measures were divided into three categories: evacuation, living, and succession. For the result, Effective disaster prevention and mitigation means "expanding the scope of assumptions by understanding natural phenomena and modern society, and acquiring the ability to respond to unexpected encounters, rather than thoroughly implementing evacuation manuals within expectations."</p>

DOI： 10.14866/ajg.2021s.0_148

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Language：Japanese   Publisher：The Association of Japanese Geographers  

In the Okada district of Mabi-cho, Kurashiki City, which experienced the heavy rain disaster in western Japan in 2018, residents are trying to hand down the flood disaster experience so that they will never have a tragic experience again. In that activity, disaster prevention and mitigation measures were divided into three categories: evacuation, living, and succession. For the result, Effective disaster prevention and mitigation means "expanding the scope of assumptions by understanding natural phenomena and modern society, and acquiring the ability to respond to unexpected encounters, rather than thoroughly implementing evacuation manuals within expectations."

DOI： 10.14866/ajg.2021s.0_148

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Language：Japanese   Publisher：公益社団法人 日本地理学会  

DOI： 10.4157/ejgeo.15.101

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Other Link： https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-18H00772/

Language：Japanese   Publisher：THE JAPANESE SOCIETY FOR GEOGRAPHICAL SCIENCES  

DOI： 10.20630/chirikagaku.75.3_117

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<p>Flood is a disaster that can be evacuated. For the reason, information such as hazard maps are released and evacuation advisories are provided, but the residents are not able to take sufficient evacuation actions at a disaster. Therefore, in order to clarify the trigger of the actual evacuation behavior, we conducted an investigation using the evacuation act curve for the victims of the Mabi flood disaster. As a result, it was found that there are three types of evacuation behavior: (1) the type that evacuation awareness increases sharply when triggered, (2) the type that evacuation awareness gradually increases, (3) the type that does not change.We have to consider policies by type. We have to consider measures for each type. We propose to provide appropriate information through leagional geography class at the school.</p>

DOI： 10.14866/ajg.2020a.0_143

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DOI： 10.14866/ajg.2019s.0_306

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<p>We investigated the heavy rain disaster in July 2018 and the characteristics on geomorphic quantity of Oda river.</p>

DOI： 10.14866/ajg.2019a.0_25

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Language：Japanese   Publisher：The Geological Society of Japan  

DOI： 10.14863/geosocabst.2019.0_237

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Language：Japanese   Publisher：The Society of Exploration Geophysicists of Japan  

<p>The geometry/angle of the deeper extension of active fault is one of the fundamental information to evaluate the magnitude of inland earthquake associated with active faulting. The information is mainly revealed by geophysical exploration that is executed across the active fault. Although the geophysical explorations were scarcely applied for strike-slip fault in Japan, we discuss the applicability of several geophysical explorations, seismic reflection and refraction survey, CSAMT (controlled source audio-magnetotelluric) survey and gravity survey for strike-slip fault in this study. The study area is located in northwest area in Kinki region in Japan, and Go-mura fault zone and Yamada fault zone are distributed in a granite area (Miyazu granite). In the seismic reflection profile, discontinuity and inflection of reflector shows the deeper geometry of active fault in 200-300 m below the surface of the ground. In some profile, discordance between subsurface structure and slip direction of the active fault were shown. Hence, the comparison between seismic reflection profile and other geophysical explorations is important in the interpretation of subsurface geometry of the active fault. Although, the seismic refraction image cannot define the strict angle of the active fault in principle, the image well indicates the low-velocity layer crushed by the strike-slip faulting. In the CSAMT survey, low-specific resistance area extended in depth clearly shows the geometry and angle of deeper part of active fault. In some image, pseudo-specific resistance can be seen in some CSAMT image, comparison to other information of geophysical survey is necessary for interpretation. Because the vertical displacement is not dominant in strike-slip faulting, the gravity survey across the strike-slip fault is generally insufficient method to detect the fault. Dense spacing of gravity stations and precise measurement allow sensing the Bouguer gravity anomaly associated with strike-slip faulting.</p>

DOI： 10.3124/segj.71.103

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Horizontal crustal strain in the Tohoku area during the twentieth century based on triangulation showed N-S extension and E-W contraction was not significant. This feature was one of the reasons why the 2011 Tohoku-oki earthquake was unexpected for many scientists. The first triangulation conducted in the late nineteenth century used a length scale defined by baseline surveys, direct measurements of short (2-10 km) baselines with steel rods. The Shionohara baseline in the Yamagata prefecture was measured in May-July 1894 and the 1894 Shonai (M7.0) earthquake occurred in its western neighbor 3 months after the measurement. The earthquake possibly elongated the baseline by as large as 5 cm or 10 ppm. However, the original length measured before the earthquake was used for the network adjustment of the entire triangulation network, causing extensive underestimation of the length scale of the network as large as 5-10 ppm in northeast Japan. The scale error effect was comparable to tectonic deformation signal over 100 years. The baseline length was re-surveyed in 2012, 1 year after the Tohoku-oki earthquake, and the result is consistent with the hypothesis of scale bias considering interseismic deformation.

DOI： 10.1186/s40623-018-0890-9

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Language：Japanese   Publisher：The Association of Japanese Geographers  

DOI： 10.14866/ajg.2018a.0_117

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DOI： 10.14866/ajg.2018s.0_000305

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DOI： 10.11462/afr.2018.49_51

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DOI： 10.14863/geosocabst.2017.0_038

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A small mud volcano in Murono, Niigata Prefecture, north-central Japan, shows active ground surface displacements, not only when large earthquakes occur in the region but also during quiescent periods between earthquake events. The site recently underwent abrupt deformations due to strong regional earthquakes in 2004, 2007, 2011, and 2014, while gradual surface deformations were reported during quiescent periods between the earthquakes. To detect the spatial distribution of the changes in the mud volcano's ground surface elevation, we carried out multi-temporal terrestrial laser scanning. Point cloud datasets were registered at different times by minimizing the distance between the closest points in different clouds for stable ground features, which revealed centimeter-to decimeter-scale deformations around the domain of the conspicuous uplift. The spatial distribution of the deformation triggered by the earthquakes, including both central uplift and peripheral subsidence, exhibits an elliptical pattern, on which open crack fractures, associated with the earthquake-triggered uplift, were formed. The displacement and stress fields for the earthquakes were modeled numerically, and anomalously high pressure and/or weakening of the surficial materials was expected for the formation of fractures in the local domain. In contrast, continuous uplift was observed during the inter-seismic quiescent periods, the domain of which seems to have changed after the strong earthquake in 2014. In the coming years, further measurements will be necessary to unravel the physical subsurface mechanics of the mud volcano.

DOI： 10.1186/s40645-016-0116-3

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Language：Japanese   Publisher：地域地理科学会  

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DOI： 10.14866/ajg.2016s.0_100244

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<p>Following the Great East Japan Earthquake, the contribution of geography was discussed from the viewpoint of delivering relief supplies after widespread disasters. Possible emergencies, obstacles, and counterplans were analyzed with the Nankai megathrust earthquake in mind. The Pacific coast of southeastern Japan, especially the Kii Peninsula, southern Shikoku, and eastern Kyushu, was an area significantly affected by the earthquake. The area was characterized by an aging population, little public transport, and poor transportation infrastructure. In addition, with the declining self-sufficiency of rural life, many commodities, including foodstuffs, consumed by rural residents are supplied from urban areas. In this current situation in Japan, delays and bottlenecks in the delivery of supplies to disaster-hit areas could cause major disruptions in relief activities. Therefore, rapid, effective relief transport systems and emergency stock systems are needed to reduce the damage. However, comprehensive approaches to these aspects lag behind in comparison with disaster-prevention measures and disaster-recovery assistance.</p>

DOI： 10.4157/ejgeo.11.526

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Other Link： https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-15K01169/

Language：English   Publisher：The Remote Sensing Society of Japan  

Surface ruptures associated with the 2014 Kamishiro fault earthquake (Mj 6.7), appeared along the Itoigawa-Shizuoka Tectonic line active fault system in the northern part of Nagano Prefecture, central Japan. We photographed it with digital cameras mounted on an unmanned aerial vehicle (UAV). Digital surface models (DSMs) were generated from the acquired photographs by applying SfM-MVS technology. The UAVs used in this study were the F450 and Phantom 2 manufactured by DJI Inc., and the cameras were the GR model manufactured by RICOH Inc. and were attached to each UAV for aerial photography. The ground control points required for generating DSMs using SfM-MVS analysis were measured using an RTK-GNSS (Leica GPS900), and the topographic profiles used for the accuracy assessment of the DSMs were measured in situ using a total station (Leica TCR705) and digital auto level (SOKKIA SDL50).<BR>As a result, we were able to create DSMs and ortho-photographs at the resolution of a few centimeters. The accuracy was assessed by comparing the topographic profiles measured by the total station and leveling with those generated by the DSMs. Validation against the nine topographic profiles revealed that the DSM had a relative height error of 4.0cm with an average standard deviation.<BR>Taking photographs from a UAV is one of the quickest and most cost-effective methods to record detailed surface topography. Generating a DSM of surface ruptures using UAV photography with SfM-MVS is particularly advantageous because ruptures will change their features quickly, and surface topographic variations of 10 cm or less cannot be recognized in field observations.

DOI： 10.11440/rssj.36.107

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We perform terrestrial laser scanning (TLS) to detect changes in surface morphology of a mud volcano in Murono, north-central Japan. The study site underwent significant deformation by a strong earthquake in 2011, and the surface deformation has continued in the following years. The point cloud datasets were obtained by TLS at three different times in 2011, 2013 and 2014. Those point clouds were aligned by cloud-based registration, which minimizes the closest point distance of point clouds of unchanged ground features, and the TLS-based point cloud data appear to be suitable for detecting centimeter-order deformations in the central domain of the mud volcano, as well as for measurements of topographic features including cracks of paved ground surface. The spatial patterns and accumulative amount of the vertical deformation during 2011-2014 captured by TLS correspond well with those previously reported based on point-based leveling surveys, supporting the validity of TLS survey.

DOI： 10.1186/s40623-016-0495-0

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Publisher：The Association of Japanese Geographers  

DOI： 10.14866/ajg.2015a.0_100001

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DOI： 10.14866/ajg.2015s.0_100166

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<p>An Mj 6.7 earthquake struck the northern part of the Nagano Prefecture, central Japan, at 22:08 JST on November 22, 2014. The earthquake was named 2014 Naganoken-hokubu earthquake, and its coseismic surface rupture has been identified along the northern part of the Kamishiro fault in the northernmost part of the Itoigawa-Shizuoka Tectonic Line active fault system. We have conducted 1) aerial-photograph interpretation, 2) field explorations, 3) photogrammetric analysis, and 4) drilling and pit excavation surveys on the northern part of the Kamishiro fault since 2005, in order to better estimate slip rates and timing of faulting on the fault. At the Shinden site, the Aira-Tanzawa volcanic ash (ca. 30 ka) was identified in the L1 terrace-surface deposit. In addition, the age of L2 terrace surface was estimated at ca. 5 ka. Because the amounts of vertical offset of the L2 terrace surface are 8.0 m and 6.5-7.0 m at the Shinden and Oide sites, vertical slip rates can be calculated to be 1.6 mm/yr and 1.3-1.4 mm/yr, respectively. We also revealed subsurface stratigraphy in the down-thrown side of the Kamishiro fault at the Oide site, and identified three possible paleoseismic events that occurred ca. 1,000-1,300 years ago, 500-600 years ago, and after 300 years ago. Further investigations are needed to better understand paleoseismic activity and long-term seismic risk of the Kamishiro fault.</p>

DOI： 10.11462/afr.2015.43_109

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DOI： 10.14866/ajg.2015s.0_100278

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<p>The 2014 M 6.7 Naganoken-hokubu earthquake was caused by movement of the Kamishiro fault located in the northernmost part of the Itoigawa-Shizuoka Tectonic Line (ISTL) active fault system, central Japan. We conducted a series of field research immediately after the earthquake to describe coseismic surface ruptures. Our description methods were: 1) field reconnaissance using pre- and post-earthquake airphotos; 2) quick measurement using staff; 3) topographic profiling using Auto Level and Total Station; and, 4) UAV and highpole SfM measurement. We identified 9-km-long coseismic surface rupture, most of which was located along the pre-existing surface trace of the Kamishiro fault. The maximum value of coseismic vertical offset was ca. 1 m or more, which was recorded at Oide in the northern part of the rupture. Based on comparison of the 2014 coseismic slip distribution with the long-term slip rate distribution, both 2014 slip amount and cumulative offset amounts of L2 and L3 terrace surfaces are larger in the northern end of the ruptures. This implies that the subsurface coseismic slip during pre-2014 earthquakes continued toward the north, similar to that during the 2014 earthquake. In addition, both coseismic slip and long-term slip rate becomes smaller toward the south, indicating that the Kamishiro area is one of the segment boundaries in the northern part of the ISTL active fault system. Further investigations of the 2014 earthquake and the Kamishiro fault are needed to understand formation of tectonic landforms, landscape development, or earthquake prediction model of active faults.</p>

DOI： 10.11462/afr.2015.43_149

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Language：Japanese   Publisher：Tokyo Geographical Society  

&emsp;Generally, the impacts of a tsunami can be understood in terms of the corresponding relationships between hazard scale and extent of building damage and loss of human life. Focusing on community-scale statistics of the municipalities of Kamaishi, Kesen'numa, Minami-sanriku, and Yamamoto, which were severely affected by the 2011 Tohoku Earthquake, significant variations are observed in the mortality rates at affected villages that experienced the same levels of building damage. Moreover, differences in the geographical locations of the villages also impact their mortality rates. A village with a high mortality rate is situated either on a coastal plain or on an inland valley plain some distance from the sea, whereas a village with a low mortality rate is paradoxically in close proximity to the sea, often facing a small bay. Close interrelationships are identified among geographical conditions and possible evacuation activities, which relate to the geographical imaginations of inhabitants based on their inherent local knowledge and interactions with physical and built environments. Interviews with survivors indicate decisions to escape could not be made quickly after the earthquake occurred. Rather, people were confused regarding the occurrence and magnitude of the tsunami and the provision of evacuation sites. The tsunami waves were often different from those that were formally forecast and broadcast, which compelled people to act flexibly. Consequently, it is argued that it is necessary to emphasize the effects of local geographies on interactions between tsunami waves and evacuation activities from a grassroots perspective when preparing for future tsunamis.

DOI： 10.5026/jgeography.124.193

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&emsp;The distribution of tsunami run-up heights generally has spatial variations, because run-up heights are controlled by coastal topography including local-scale landforms such as natural levees, in addition to land use. Focusing on relationships among coastal topography, land conditions, and tsunami run-up heights of historical tsunamis&mdash;Meiji Sanriku (1896 A.D.), Syowa Sanriku (1933 A.D.), and Chilean Sanriku (1960 A.D.) tsunamis&mdash;along the Sanriku coast, it is found that the wavelength of a tsunami determines inundation areas as well as run-up heights. Small bays facing the Pacific Ocean are sensitive to short wavelength tsunamis, and large bays are sensitive to long wavelength tsunamis. The tsunami observed off Kamaishi during the 2011 off the Pacific coast of Tohoku Earthquake was composed of both short and long wavelength components. We examined run-up heights of the Tohoku tsunami, and found that: (1) coastal areas north of Kamaishi and south of Yamamoto were mainly attacked by short wavelength tsunamis; and (2) no evidence of short wavelength tsunamis was observed from Ofunato to the Oshika Peninsula. This observation coincides with the geomorphologically proposed source fault model, and indicates that the extraordinary large slip along the shallow part of the plate boundary off Sendai, proposed by seismological and geodesic analyses, is not needed to explain the run-up heights of the Tohoku tsunami. To better understand spatial variations of tsunami run-up heights, submarine crustal movements, and source faults, a detailed analysis is required of coastal topography, land conditions, and submarine tectonic landforms from the perspective of geomorphology.

DOI： 10.5026/jgeography.124.177

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This study was analyzed building damage and human damages by the 1944 Tonankai earthquake and the Mikawa earthquake in Aichi Prefecture. We compared in detail the number of collapse house, victims, and physical geographic condition, at the village scale. As the result we can show the feature of disaster type by the earthquake shock and the displacement. On the earthquake shock, houses are destroyed. Since it takes time to be completely destroyed, people has the time to escape from the onslaught of violence. On the other hand, on the displacement houses are destroyed in a moment before people escape.

DOI： 10.14866/ajg.2015s.0_100231

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&emsp;Spatial variations of hazards such as strong ground motion and tsunami inundation are a key element for obtaining a geographical understanding of natural disasters. However, detailed distribution of tsunami run-up heights for the devastating tsunami associated with the 2011 off the Pacific coast of Tohoku earthquake is not available. A GIS analysis of tsunami inundation areas is conducted from data collected by the Tsunami Damage Mapping Team and from post-tsunami 2-m mesh and 5-m mesh digital elevation models (DEM) after the Geospatial Information Authority of Japan, in order to produce the Tsunami Run-up Height Map, which includes polygon data of inundation areas with elevation data at each point. Horizontal shifts of orthophotos taken just after the tsunami are corrected using a Helmert transformation. The map covers Iwate Prefecture, Miyagi Prefecture, and the northern part of Fukushima Prefecture continuously at high resolutions, and reveals spatial variations of tsunami run-up heights in detail. These variations are caused by: 1) landforms at each site, such as coastal plains, valleys, bays, and beach ridges, as well as their directions and magnitudes, and 2) source locations, interference, and wavelengths of the tsunami, as implied by a previous study. The map supports examination carried out on source fault models and simulation results of tsunamis from a geographical viewpoint. At the same time, the methodology to produce the map would be useful for systematically revealing run-up height distribution, in addition to inundation areas immediately after future tsunamis.

DOI： 10.5026/jgeography.124.157

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DOI： 10.14866/ajg.2015s.0_100208

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Language：Japanese   Publisher：Tokyo Geographical Society  

DOI： 10.5026/jgeography.124.vii

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DOI： 10.5026/jgeography.124.x

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Publisher：The Geological Society of Japan  

DOI： 10.14863/geosocabst.2014.0_594

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DOI： 10.4157/grj.87.421

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DOI： 10.14866/ajg.2014a.0_53

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Recession rates of four waterfalls formed by the surface deformation of the Chelungpu Fault at the time of Chi-Chi Earthquake on September 21, 1999 in central Taiwan were measured in the field and assessed with an empirical model of waterfall erosion. The model represents the balance between the erosive force of streams versus bedrock resistance with relevant environmental parameters of discharge (drainage area and precipitation), waterfall form and bedrock strength. The recession rates of three waterfalls increased from the first 6 years to the following 4 years. This increase in the recession rates basically corresponds to the changes in environmental factors including precipitation increase and waterfall width narrowing. The recession rate of another waterfall decreased, but this can be explained by artificial modification of riverbed. The recession rates are very high comparing with waterfalls in other places, probably due to large amount of hard gravels transported on the weak bedrock from the upstream areas.

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Other Link： http://dl.ndl.go.jp/info:ndljp/pid/10808629

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Precise levelling surveys were conducted across the central Longitudinal Valley Fault, eastern Taiwan, to understand the deformation of the transition zone between the stable fault creep area and the asperity area. In order to investigate the surface relationship between the fault creep area and the geological condition of the transition zone, we established levelling routes in the Yuli, Chike-san, and Reishuei areas. The Yuli area forms the geological boundary of the Lichi Melange Formation, which is composed of chaotic mudstones containing numerous exotic blocks of various sizes and lithologies. Along the Yuli route, located on the Lichi Melange, an uplift rate of 30 mm/yr was detected during the period 2010-2012, suggesting that aseismic fault creep might be continuing with long-term stability. Along the Chike-san route, a vertical deformation rate of 8 mm/yr was detected in the period 2010-2011. However, a large deformation with an uplift rate of 40 mm/yr was detected in the period 2011-2012. Along the Reisuei route, we detected a deformation of 8 mm/yr in the period 2011-2012.A two-dimensional single-fault model was developed to discuss the slip distributions in the periods 2010-2011 and 2011-2012. Relatively large slip rates were estimated at two parts of the fault plane one at a depth of similar to 1.5 km and another at a depth of similar to 4 km in both periods. Because both parts of the fault plane show approximately the same slip distribution, we believe that the detected deformation resulted from an episodic acceleration event of creeping slip.The northern limit of the stable creep area may be the Yuli area. The episodic creep event occurred in the transition zone between the stable fault creep area and the asperity area. The boundary between the stable creep area and the episodic creep area is consistent with the geological boundary of the Lichi Melange Formation. (C) 2013 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.tecto.2013.07.027

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We find three coral boulders (approx. 5 m across) resting on the Holocene coral terrace on the Jiupeng coast of southeastern Taiwan. Three exotic corals on the outer part of the boulders are dated at ca. 5000 yr BP which is similar to that of in situ corals composing the Holocene terrace. We interpret that these boulders were broken off from the coral terrace and were transported by tsunami waves, although the timing of the paleotsunami is not determined at this stage.

DOI： 10.3319/TAO.2012.09.14.01(TT)

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DOI： 10.14866/ajg.2013a.0_100022

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DOI： 10.14866/ajg.2013s.0_128

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DOI： 10.14866/ajg.2013a.0_100091

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Other Link： https://soar-ir.repo.nii.ac.jp/records/16474

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In this paper, we examine the interrelationships between locally varied casualties, and physical mechanisms of tsunami flows, physical geographies and social conditions of the localities, and then discuss what caused the catastrophe in the 2011 Tohoku Earthquake.

DOI： 10.14866/ajg.2012a.0_100058

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The March 11, 2011, earthquake off the Pacific coast of northeastern Japan caused large tsunami. Tsunami-damaged areas were mapped on a scale of 1 : 25,000 based on the interpretation of stereopaired aerial photographs taken immediately after the earthquake by the Geospatial Information Authority of Japan. The area interpreted in this study was from Aomori to Chiba prefecture, except for the restricted area around the Fukushima nuclear power plant. Areas for which no aerial photographs were available were mapped using Google Earth and other sources. The purpose of mapping was to provide prompt basic information on the extent of tsunami invasion and distribution of devastated areas for all people taking countermeasures against the disaster. The lessons from our mapping area are that 1) aerial photographs should be taken as soon as possible after disasters and 2) a working team should be quickly arranged to map damaged areas and release the results.

DOI： 10.4157/ejgeo.7.214

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DOI： 10.14866/ajg.2012s.0_100262

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Focusing on the river-course change of the Isuzu river, we suppose the event was caused by the giant tsunami. We found the evidence in alluvial plain by Geo-slicer.

DOI： 10.14866/ajg.2012a.0_100153

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DOI： 10.14866/ajg.2011s.0.247.0

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DOI： 10.5575/geosoc.117.1.I_II

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Paleotsunami is one of the indicators for reconstruction of paleoearthquakes. It has been generally considered that the east coast of Taiwan has not been affected by large tsunami, due to the absence of documented records in the short historical time, and also due to steep offshore submarine morphology. A legend of the Ami tribe says, however, that strong waves have rushed toward the northern part of the east coast.In addition, a local historian tells a story that a sudden disappearance of vegetation has occurred at Chenggong town at ca. 150 years ago. We infer that this environmental change may record a tsunami event on this coast and wish to confirm the occurrence of tsunami by excavation of Holocene deposits. The excavated sites are located on the lower Holocene marine terraces at 15-20 m asl at Chenggong area. The first excavation was done by hand-augering on Sept. 2009, and the second one was by using Geoslicer at four sites on March, 2010. In addition, we have observed coastal feature along the east coast of Honchuan Peninsula. This preliminary report provides two lines of geological evidences for possible tsunami origin. One is the presence of two abrupt facies changes from terrestrial condition to marine or brackish condition, event I and II, at Site 1. Available radiocarbon date suggests the event I occurred at 1850 to 1600 cal yr BP, thus event II is further younger than this age. We are working on various kinds of analysis, including radiocarbon dating, to confirm the tsunami origin for observed features.

DOI： 10.14866/ajg.2010f.0.88.0

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Language：Japanese   Publisher：Japanese Society for Active Fault Studies  

The Itoigawa-Shizuoka Tectonic Line active fault zone is one of the largest active faults in Japan, with a length of 150 km. The previous paleoseismological studies revealed a 14% possibility of a large earthquake in the next 30 years. The Japanese Ministry of Education, Culture, Sports, Science and Technology has initiated an intensive research project on this fault zone in 2005, in which we have conducted a tectonic geomorphological study on the northern part of the fault zone in order to predict its coseismic behavior. We have interpreted largescale aerial photographs taken not only in recent years but also in the 1940s and 1960s for examining faultrelated topography including those which have been already modified or destroyed, and then conducted a field survey to determine ages of geomorphic surfaces. We also carried out photogrammetric analyses which have resulted in our highly-dense offset data whose spatial intervals are of 500-1000 meters in average. Based on these surveys, we estimated a net-slip rate distribution along the northern part of the fault zone, and calculated coseismic slip distribution assuming that the fault zone follows the characteristic earthquake model. Largeroffset areas were identified in the Hakuba Village and the Ikeda Town. These peaks of surficial slip distribution would imply subsurface fault which generate strong ground motion. The maximum vertical offset during the last earthquake is estimated to be 5 - 6 meters. Therefore, the coseismic net slip would exeed 10 meters when we assume the fault-slip responds to the maximum shear stress. Our detailed coseismic slip distribution and the subsurface fault geometry predict a moment magnitude of 7.5 for the northern part of the fault zone.

DOI： 10.11462/afr.2010.33_1

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DOI： 10.14866/ajg.2010s.0.247.0

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Recession of waterfalls is a significant agent in bedrock river erosion and development, but field data on waterfall recession rates have been limited due mainly to the lack of information on initiation age and recession distance of waterfalls. This study examines recession rates of fault-scarp waterfalls that were formed along the Chelungpu surface fault at the 921 Chi-Chi Earthquake on September 21, 1999 at central Taiwan. Our field measurements reveal the 6-year mean recession rate of the waterfalls to be 3.3-58.2m/y, which is considerably higher than any other waterfall recession rate in the world. In order to explore the factors affecting the observed high waterfall recession rate, relationships between the waterfall recession rate and relevant physical parameters (comprising erosive force and bedrock resistance) are examined using a previously proposed empirical model. Applying field measured parameters at the rivers, the previously established equation provides an estimated recession rate of 0.6-3.9m/y, which is much lower than the actual recession rate. The discrepancy between the actual and equation-derived recession rates is likely due to abundant abrasive material in the rivers, which may considerably enhance waterfall recession.

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The Chelungpu Fault, Taiwan, records the surface rupture by the 1999 Chichi earthquake and abundant information has been obtained on paleoseismology on this fault during the last 10 years. This study area, located on the central part of the Chelungpu Fault, is known as one of the type localities of the surface rupture, but no paleoseismological study was carried out. This paper reports the trench log across the Chelungpu Fault preserved at the Earthquake Museum of Taiwan and tries to reconstruct the faulting history at this site based on 10 bore hole data on the location of the museum. Trench log indicates the displacement of terrace deposits and underlying bedrock by the 1999 earthquake. Four subparallel faults are observed within 1.8 m width, corresponding to the location of the surface rupture. Estimated height difference of bedrock surface based on the bedrock height by bore hole data is more than 4.2 m, significantly larger than the offset by the 1999 earthquake (2-2.5 m). This fact implies that at least two earthquake events including the 921 earthquake occurred at this site. We also estimate the fault plane dips eastward at about 30 degree, based on the location and stratigraphy of one bore hole which penetrates to the terrace gravel on the footwall through the bedrock.

DOI： 10.11462/afr.2009.31_33

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Language：Japanese   Publisher：Disaster Prevention Research Institute Kyoto University  

The memories of past disaster experiences tend to fade out quickly. Survivors do not want to keep horrible memories, and try to forget it. Although the transference of lessons learnt through past disaster experience is considered as one of ways to motivate people to take disaster preventive action, the mechanism of how the personal memory form collective memory and transfer to other generation/region is still not clear. In this study, we focus on the memory of earthquake disaster in different region, Turkey, Taiwan and Indonesia. Through field studies we try to find out what kind of memory do people talk as personal memory, and how those personal memory form collective memory and will be transferred.

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Other Link： http://hdl.handle.net/2433/129329

Publisher：The Association of Japanese Geographers  

The geographical information with regard to active faults (for example; precise location, cumulative amount and shape of deformation, and slip-rate) is compiled on the &ldquo;Web-GIS based active fault information system for the Itoi-gawa-Shizuoka Tectonic Line&rdquo;. This can be a compilation of the basic information not only for earthquake anticipa-tion, but also for land use planning in order to mitigate earthquake disaster. These fundamental data and visual graphics illustrating the relation between active faults and tectonic landforms are compiled on the system, which became opened for public. We are here presenting methodology for constituting the system as an effected hazard map toward disaster mitigation. Tectonic geomorphological survey of the northern and middle Itoigawa-Shizuoka Tectonic Line was conducted and it clarifies the detailed distribution of the slip-rates of the fault. That would enable us to forecast the behavior of the fault and to estimate the strong ground motion associated with an earthquake. Fur-thermore, the digital elevation model with high density and high precision was constructed photogrammetrically by using 1:15,000 scale aerial photographs. The aerial photographs taken in the 1940s or 1960s were also used in areas where tectonic landforms had already been artificially modified; this was intended to reconstruct the original land-forms. The landform deformations by faulting were analyzed densely from many transactions that were measured under the photogrammetrical system.

DOI： 10.4157/ejgeo.4.37

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Language：Japanese   Publisher：The Association of Japanese Geographers  

DOI： 10.14866/ajg.2008s.0.124.0

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DOI： 10.14866/ajg.2008s.0.172.0

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DOI： 10.14866/ajg.2008s.0.203.0

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DOI： 10.14866/ajg.2008s.0.123.0

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Language：English  

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Other Link： http://id.nii.ac.jp/1141/00110962/

Language：Japanese   Publisher：The University of Tokyo  

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DOI： 10.15083/0000032484

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Other Link： http://hdl.handle.net/2261/8148

Language：Japanese   Publisher：The University of Tokyo  

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DOI： 10.15083/0000032483

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Other Link： http://hdl.handle.net/2261/8147

Language：Japanese   Publisher：The University of Tokyo  

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DOI： 10.15083/0000032482

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Other Link： http://hdl.handle.net/2261/8146

Language：Japanese   Publisher：The University of Tokyo  

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DOI： 10.15083/0000032488

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Other Link： http://hdl.handle.net/2261/8152

Language：Japanese   Publisher：The University of Tokyo  

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DOI： 10.15083/0000032487

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Other Link： http://hdl.handle.net/2261/8151

Language：Japanese   Publisher：Japanese Society for Active Fault Studies  

We conducted a tectonic geomorphological survey in the southern part of the Matsumoto Basin and the south coast of the Suwa Basin, along the middle part of the Itoigawa-Shizuoka Tectonic Line (ISTL) active fault system. Procedures of this study are as follows; 1) aerial photo analysis and field surveys,2) mapping of geomorphic surfaces and reconstruction of geomorphic evolution,3) mapping of tectonic landforms which explain the geomorphic evolution reasonably,4) photogrammetrical measurement of vertical offset by construction of cross sections and calculation of vertical offset rates,5) measurement of horizontal offset of geomorphic markers and calculation of horizontal rates. Vertical/lateral offset rates were estimated based on vertical/lateral offset of geomorphic markers, such as terraces and ages of them (H: older than 120 ka, M1: 100 ka, M2: 40-65 ka, Lla: 20 ka, Lib: 10 ka, L2: 4-7 ka, L3: 1-2 ka). LiDAR method is also used for measurement of lateral offset<BR>Although mapped fault trace in the study area is similar to existing papers, different results were obtained in some areas. One of the remarkable results is that the Gofukuji fault in eastern margin of the Matsumoto Basin connects smoothly with the faults in northern end of the Suwa Basin. These faults have left lateral offset.<BR>We obtained 108 vertical/ left lateral offset rates in the study area. The vertical and leftlateral slip rates are estimated to be 0.1-2.0 mm/yr and 0.6-8.5 mm/yr, respectively.

DOI： 10.11462/afr1985.2007.27_169

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Language：Japanese   Publisher：Japanese Society for Active Fault Studies  

We conducted a tectonic geomorphological survey in the northeastern margin of the Suwa Basin (in the area between Okaya and Chino), along the middle part of the Itoigawa-Shizuoka Tectonic Line Active Fault System (ISTL). Procedure of this study is as follows; 1) aerial photo analysis and field survey,2) mapping of geomorphic surfaces and reconstruction of geomorphic evolution,3) mapping of tectonic landforms which explains the geomorphic evolution reasonably,4) measurement of vertical offset by construction of cross sections and calculation of vertical offset rates,5) measurement of horizontal offset of geomorphic markers (e. g., terrace scarps, small valleys) and calculation of horizontal offset rates. Vertical/horizontal offset rates were estimated based on offset of geomorphic markers (fluvial terraces) and ages of the terraces (H, older than 120 ka; Ml,90-100 ka; M2,40-65 ka; Li a,20 ka; Lib,10 ka; L2,4-7 ka; L3,1-2 ka). Although mapped faults in this study are similar to existing papers, different results were obtained in some areas as follows; 1) we judged fault traces in existing papers near the Suwa Taisha Harumiya which lies on the right bank of the Togawa River is not a tectonic landform but an erosional scarp,2) we judged that broad gentle slope at Suwa Taisha Akimiya which is interpreted as flexural scarp is not a tectonic landform but a depositional landform of landslide deposits,3) we judged that the (fault) scarp in Kuwabara is not a tectonic landform but an erosional scarp,4) fault scarps which lie along boundary between the Suwa Basin and mountainous area at Uehara are newly mapped,5) the fault scarp near the Chino station at the right bank of the Kamikawa River is newly mapped as certainly located fault,6) the fault scarp which deforms L3 surface in a valley bottom at Sakamuro is newly mapped. We constructed 41 cross sections and obtained 47 vertical/lateral offset rates. Based on obtained vertical/horizontal offset rate, faults in the study area can be classified into three or four segments, although we could obtain only minimum vertical offset rates in many areas. The most southeastern segment is interpreted as a main fault which is inferred to construct a pull-apart basin. The other fault segments are interpreted as secondary faults of the main faults, based on the fact that these fault segments have short length (3-4 km), and that the fault segments have gentle round shaped fault traces.

DOI： 10.11462/afr1985.2007.27_147

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Language：Japanese   Publisher：The Association of Japanese Geographers  

DOI： 10.14866/ajg.2007s.0.78.0

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DOI： 10.15083/0000032486

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Other Link： http://hdl.handle.net/2261/8150

Language：Japanese   Publisher：The University of Tokyo  

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DOI： 10.15083/0000032485

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Other Link： http://hdl.handle.net/2261/8149

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Language：Japanese   Publisher：Tokyo Geographical Society  

The Eastern margin of the Yokote Basin Fault Zone (EYBFZ) is one of the seismogenic reverse faults that developed in Northeast Japan, generating the 1896 Rikuu Earthquake (M7.2). The EYBFZ is divided into range boundary fault (Kawaguchi Fault) and frontal fault. The major segment of the frontal fault consists of three faults : the Shiraiwa Fault, the Ota Fault, and the Senya Fault, at which coseismic surface ruptures with irregular and highly sinuous traces, gaps and echelon steps occurred during the 1896 Earthquake. In the study area, the irregular coseismic surface ruptures probably originate from differences in fault geometries and sedimentary conditions, which are associated with thrust-front migration in the Quaternary. We discuss the relationships among fault traces, geomorphic displacements, and fault geometries on the Senya Fault and the Kawaguchi Fault, based on data from high-resolution seismic reflection profiling, investigations into tectonic geomorphology and structural geology with the help of the balanced cross-section method.<BR>The seismic image obtained shows changes of geomorphic and geologic features around the Senya Hills expressed as differences in faulting geometries along the Senya Fault and the Kawaguchi Fault. In fact, the Senya Hills are situated as an unsymmetrical ordering.The disparity in the timing of thrust-front migration affects the development of fluvial surfaces, which are related to the appearance of the fault scarp on the surface. That is why, in the central portion of the Senya Hills, the Senya Fault is a typical emergent thrust with flat-ramp structures associated with the uplifting and the back-tilting of late Quaternary fluvial terraces. On the other hand, in the northern portion, the Senya Fault is a concealed thrust with step-like geometry and prominent folding and small faults in the hanging wall. The small faults infer the structure of the tectonic scarp and short wavelength deformation on the surface. This means that the Senya Fault at the central portion preceded the northern portion as an emergent fault. Moreover, fault traces show different dips between central and northern portions. The dip of the central portion is lower than that of the northern portion.<BR>By restoring the balanced cross-sections and assuming the uniform net-slip rate, the initial thrusting along the boundary faults is retroactive to 2.02.6 Ma at the central portion and 1.8 2.3 Ma at the northern portion. The initiation of thrust front migration from the boundary faults to the frontal faults is ca.1.6 Ma at the central portion and 0.6Ma at the northern portion.

DOI： 10.5026/jgeography.115.6_691

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DOI： 10.15083/0000032514

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Other Link： https://repository.dl.itc.u-tokyo.ac.jp/records/32514

Language：Japanese   Publisher：The University of Tokyo  

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DOI： 10.15083/0000032515

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Other Link： http://hdl.handle.net/2261/5913

Language：Japanese   Publisher：Japanese Society for Active Fault Studies  

We conducted a tectonic geomorphological survey along the northern part of the Itoigawa-Shizuoka Tectonic Line (ISTL) with support from the Ministry of Education, Culture, Sports, Science and Technology of Japan as one of the intensive survey on ISTL fault system. This survey aims to clarify the detailed distribution of the slip rates of this fault system, which provides the essential data set to predict the coseismic behavior and to estimate the strong ground motion simulation. In order to achieve this purpose, the active fault traces are newly mapped along the northern part of the ISTL through interpretations of aerial photographs archived in the 1940s and 1960s at scales of 1: 10,000 and 1: 20,000, respectively. This aerial photo analysis was also supplemented and reinforced by field observations.<BR>One of the remarkable results by using this data set is a large number of, here 84, photogrammetrically measured landform transections to quantify the tectonic deformations. We could calculate vertical slip rates of the faults at 74 points, based on the estimated ages of terraces (H: 120 kyrs, M: 50-100 kyrs, Ll: 10-20 kyrs, L2: 4-7 kyrs, L3: 1-2 kyrs). The vertical slip rates distributed in the northern part of the study area show 0.2-5.5 mm/yr on the L terraces (less than 20 kyrs) and 0.05-0.9 mm/yr on the M and H terraces (more than 50 kyrs). The vertical slip rates of the faults located in the central and southern part of the study area are 0.2-3.1 mm/yr.

DOI： 10.11462/afr1985.2006.26_121

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DOI： 10.15083/0000032516

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Other Link： https://repository.dl.itc.u-tokyo.ac.jp/records/32516

Language：Japanese   Publisher：活断層研究会  

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The North Matsuda fault in the Kozu-Matsuda fault zone is one of the active fault system, showing the largest vertical component of slip rate onshore Japanese islands. The Kozu-Matsuda fault system is considered as a part of the northern margin of the Philippine Sea plate. It is necessary to obtain the horizontal shortening component of slip rate of the North Matsuda fault for a better understanding of active tectonics in the northern margin of the Philippine Sea plate. To reveal the subsurface structure of the North Matsuda fault, high-resolution shallow seismic reflection survey with about 3.2 km line length was carried out across the fault, A kind of accelerated weight drop system named as Yuatsu Impactor (JGI Inc. ) was used as seismic source which has wide band frequency spectrum. Both the standard shot intervals and group intervals of geophones were 10 m. The Sakawa River near the center of the line obstructed both shooting and geophone setting, and the half of the line in the Matsudayama Mountains was severely crooked. Although such a bad survey conditions, the seismic section after careful data processing shows a drastic structural change and a north dipping thrust fault with 18 degrees near the Sakawa River, which is suggested as the North Matsuda fault. The fault trace revealed by a result of the seismic reflection survey is exactly located along the Sakawa River.

DOI： 10.11462/afr1985.2005.25_85

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Language：Japanese   Publisher：活断層研究会  

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Language：Japanese   Publisher：海洋出版  

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Language：Japanese   Publisher：The Geological Society of Japan  

DOI： 10.14863/geosocabst.2004.abst.0_100_2

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DOI： 10.15083/0000032587

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Other Link： http://hdl.handle.net/2261/13246

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Language：Japanese   Publisher：活断層研究会  

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Language：Japanese   Publisher：Japanese Society for Active Fault Studies  

A high-resolution P-wave seismic reflection profile was acquired across the toe of the Senya thrust, northern Honshu, Japan, to test the applicability of profiling using a hummer source (3.5 kg). Seismic data was recorded by a portable recording system (60 ch), with 28Hz geophones spaced at 0.5m intervals, and processed by standard Common Mid-Point (CMP) method. The obtained seismic section clearly demonstrates an eastdipping thrust down to 40-m in depth. The geometry of the thrust well fit to the subsurface structure estimated by drill core data.

DOI： 10.11462/afr1985.2001.20_40

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Language：Japanese   Publisher：The Geodetic Society of Japan  

We carried out gravity surveying along a profile of the reflection seismological prospecting in the northern part of the Itoigawa-Shizuoka Tectonic Line (ISTL). Combined use of gravity and seismic data enables us to construct a 2-D subsurface density model. We also pre sent a 3-D model which is consistent with the previous works on gravity and reflection/refraction prospecting. Both 2-D and 3-D models show a reverse fault structure dipping toward the east. We do not find any thrusting structure dipping toward the west as implied from the up lifting of the Hida range.

DOI： 10.11366/sokuchi1954.46.177

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By excavation of the Ochikawa-Ichinomiya remain located on the flood plain along Tama River near the boundary between Tama City and Hino City, Tokyo metropolitan area, a fault was found in young alluvium. This fault is regarded as the continuation of Tachikawa fault, a major active fault existing in the left bank area of Tama River, because it is located on the southeastern extension of Tachikawa fault line, and its strike is almost parallel to the Tachikawa fault.<BR>Detailed investigation of the fault outcrop made it clear that the last faulting event on the Tachikawa fault had occurred after A. D.1020-1158, the mid-Heian period. At this place, the last faulting event was dominantly strike slip with horizontal shortening of about 0.6 m.

DOI： 10.11462/afr1985.1996.15_1

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