著者
神谷 泉 小荒井 衛 関口 辰夫 佐藤 浩 中埜 貴元 岩橋 純子
出版者
公益社団法人 東京地学協会
雑誌
地学雑誌 (ISSN:0022135X)
巻号頁・発行日
vol.122, no.5, pp.854-874, 2013-10-25 (Released:2013-10-31)
参考文献数
31

SAR interferometry is widely used for dense measurements of surface displacements caused by earthquakes, but the method cannot be applied if displacements are too large. The near-epicentral area of the Iwate–Miyagi Nairiku Earthquake in 2008 is an inapplicable case. Therefore, we applied photogrammetry to measure surface displacement caused by the earthquake. The maximum horizontal and vertical displacements were found to be 5.3 m and 2.9 m, respectively. We recognized three lines where displacement changes abruptly. The displacement distribution is like that of a reverse fault along the first line (A–B), an east-rising fault along the second line (F–G–H; west of line A–B), and a left-lateral fault along the third line (B–C; between line A–B and line F–G–H). The earthquake source fault reaches or approaches the ground surface at line A–B, with slippage decreasing toward the ground surface. The fault-like large surface deformation found north of the Aratozawa Dam is on the first line. The fault-like deformation was caused by the motion of the earthquake source fault, and the relative displacement of the fault-like deformation was enlarged by local causes. A gravitational mass movement found north of the fault-like deformation is one cause. Because the width of the rising area is small, only 3.5 km, at the southwestern side of line B–C, the slip of the earthquake source fault is mainly distributed near the ground. Line F–G–H suggests the existence of a geological structure that causes the abrupt changes of vertical displacement without a horizontal displacement, for example a high-angle fault.  We assumed: (1) the slip on the main fault is distributed only in a shallow area at the southern part of the main fault and only in a deep area at the northern part; and, (2) the difference of slip caused two lateral faults between southern and northern parts. The assumption qualitatively explains many observation results, such as why there is an abrupt change of horizontal displacement along line B–C and why line F–G–H has a convex part to the east. We found a correlation between the occurrence of large landslides and abrupt changes of displacement, in other words large surface strain. The following mechanisms are possible causes of the correlation: (1) stress from surface strain increased large landslides; (2) faults (not only the main fault) may exist under the focused areas, rupture of faults caused both large surface strain and large seismic motion, and seismic motion induced large land slides. We also found that landslides and slope failures occurred densely over the slipping area on the main fault, based on the assumptions in the previous paragraph. Because photogrammetric measurements need interactive observations, we could avoid observations on possible embanking areas. Because photogrammetry allows intensive measurements at interesting areas, we revealed a two flexure-like distribution of vertical displacement. Therefore, photogrammetry is an effective method for measuring surface displacement caused by an earthquake.
著者
小荒井 衛 中埜 貴元
出版者
一般社団法人 地理情報システム学会
雑誌
GIS-理論と応用 (ISSN:13405381)
巻号頁・発行日
vol.21, no.1, pp.1-7, 2013-06-30 (Released:2019-02-28)
参考文献数
12

We considered the specification of temporal geospatial information, and produced a temporal geospatial dataset of the area close to Kenkyu-Gakuen Station of the Tsukuba Express in Tsukuba City. Using geospatial data of each year generated from the temporal geospatial dataset, we conducted a temporal spatial analysis of human impacts such as the development of a new traffic network and land surface change such as land use. Effective temporal spatial analysis is possible using a temporal geospatial dataset if the dataset is revised with high temporal resolution.
著者
中埜 貴元 小荒井 衛 星野 実 釜井 俊孝 太田 英将
出版者
公益社団法人 日本地すべり学会
雑誌
日本地すべり学会誌 (ISSN:13483986)
巻号頁・発行日
vol.49, no.4, pp.164-173, 2012-07-25 (Released:2013-10-01)
参考文献数
17
被引用文献数
1

地震時に発生が懸念される大規模盛土造成地における滑動的変動被害について,その被害予測を効率的に実施するためには,国土交通省の「大規模盛土造成地の変動予測調査ガイドライン」の第一次スクリーニングですべての盛土に共通して得られる地形情報のみを利用して,盛土の相対的な滑動崩落危険度を評価する必要がある。そこで,盛土地形の計測と地震時滑動崩落に対する相対的な安全性の評価支援が可能なシステムを構築し,その有効性を検証した。
著者
中埜 貴元 小荒井 衛 宇根 寛
出版者
公益社団法人 東京地学協会
雑誌
地学雑誌 (ISSN:0022135X)
巻号頁・発行日
vol.124, no.2, pp.259-271, 2015-04-25 (Released:2015-05-14)
参考文献数
23
被引用文献数
5 6

Landform classification data are useful for assessing land liquefaction. Koarai et al. (2013) suggested a comprehensive risk assessment table for land liquefaction by combining 7.5-arc-second Japan engineering geomorphologic classification data (Wakamatsu and Matsuoka, 2009) with seismic intensity. The Geospatial Information Authority of Japan (2007) suggested a risk assessment standard for land liquefaction using land condition data produced by the Geospatial Information Authority of Japan. Our new hazard assessment standard for land liquefaction is based on land condition data and a risk assessment table produced by Koarai et al. (2013). Furthermore, a landform classification and hazard assessment standard of land liquefaction is suggested to create a simple land liquefaction hazard map. This information allows land liquefaction hazard to be assessed from land condition data or 7.5-arc-second Japan engineering geomorphologic classification data and to interconvert both land liquefaction hazard assessments.
著者
小荒井 衛 吉田 剛司 長澤 良太 中埜 貴元 乙井 康成 日置 佳之 山下 亜紀郎 佐藤 浩 司馬 愛美子 中山 詩織 西 謙一
出版者
日本地図学会
雑誌
地図 (ISSN:00094897)
巻号頁・発行日
vol.50, no.3, pp.3_16-3_31, 2012 (Released:2015-11-07)
参考文献数
29

This study develops the way to produce landscape ecological map for estimation of biodiversity using the airborne laser survey (LiDAR survey) data. We produce the landscape ecological map consists of three dimensional vegetation structure and micro topography under the forest using LiDAR. Two study areas were selected. One is the Shiretoko Peninsula (Mt. Rausu and Shiretoko Corp), Hokkaido Island as World Natural Heritage Area of Japan. Another is the Chugoku Mountains (north foots of Mt. Dogo) which are many historical iron sand mining sites (Kanna-Nagashi) as Satoyama Region (secondary forest area).Basic legend of landscape-ecological map consists of ecotopes which are the combination of vegetation classification and landform classification. Vegetation classification is three dimensional vegetation structure classification using high density random points data, detailed DSM (Digital Surface Model) and detailed DEM (Digital Elevation Model) by LiDAR data. Landform classification is micro landform classification using detailed DEM by LiDAR data.Using LiDAR data in summer and autumn seasons, 0.5m grid DSM and DEM in summer and 1 or 2m grid DSM and DEM in autumn are obtained. Vegetation classification has been down using three dimensional vegetation structure detected by the difference between LiDAR data in two seasons. The legend of three dimensional vegetation structure maps consists of the combination of vegetation height, thickness of crown and difference in two seasons (deciduous dingle layer tree, deciduous multi layer tree and evergreen tree). Landform classification has been done by automatic landform classification method combined three categories, such as slope degree, texture (roughness) and convexity of autumn DEM. The results of overlay analysis between vegetation classification and landform classification are as follows: On Shiretoko Peninsula, three dimensional vegetation structures are dominated by site elevation compared with micro landform classification. On Chugoku Mountains, some early deciduous high think crown trees (a kind of nut) are located in historical mining sites (Kanna-Nagashi) with following micro landform categories such as gentle slope, concave and rough texture.Grid size of landscape ecological maps is 4m, because the grid size is corresponding on tree crown size. At first, we produced 1m grid vegetation maps and automated landform classification maps, and then we resampled 4m grid data from 1m grid data. These maps would be introduced as example of LiDAR application for ecological field.
著者
小荒井 衛 宇根 寛 西村 卓也 矢来 博司 飛田 幹男 佐藤 浩
出版者
一般社団法人 日本地質学会
雑誌
地質学雑誌 (ISSN:00167630)
巻号頁・発行日
vol.116, no.11, pp.602-614, 2010 (Released:2011-03-02)
参考文献数
49
被引用文献数
2 5

2007年7月16日に発生した「平成19年(2007年)新潟県中越沖地震(マグニチュード6.8)」について,陸域観測衛星「だいち(ALOS)」に搭載されている合成開口レーダ(PALSAR)による干渉SAR解析を行った.SAR干渉画像は,震源域近くの断層運動による地殻変動のみならず,震源から15 km東に離れた西山丘陵において,活褶曲の向斜軸に沿って幅1.5 km長さ15 kmの帯状隆起域が検出された.筆者らは,これは地震に伴って発生した間欠的な活褶曲の成長を示す直接的な証拠であると考えた.加えてSAR干渉画像は,柏崎市の中心街において,砂丘地盤の液状化や側方流動などの非地震性の地表変動についても検出することが出来た.
著者
小荒井 衛 小松原 琢 黒木 貴一 岡谷 隆基 中埜 貴元
出版者
国土地理院・地理地殻活動研究センター
雑誌
基盤研究(C)
巻号頁・発行日
2009

芋川流域で火山灰分析に基づく段丘編年を行った.芋川流域で最も高位の段丘から浅間草津火山灰(As-K)が検出されなかったことから,この段丘面は16,500年以降に形成された面と推察される.段丘形成年代から小松倉背斜の成長速度の見積もると,0.8~1.9×10^<-6>/年となり,西山丘陵の活褶曲の成長速度や小千谷地区の活褶曲の成長速度と,オーダー的には同程度である.長野県・新潟県県境付近の地震では,逆断層の上盤側で,地質,地質構造,既存活断層の分布等に支配される形で地盤災害が集中しており,今回の地震に伴い松之山背斜が成長した可能性が指摘できた.