著者

Mitsuhisa WATANABE

出版者

Tokyo Geographical Society

雑誌

Journal of Geography (Chigaku Zasshi) (ISSN:0022135X)

巻号頁・発行日

vol.116, no.3-4, pp.387-393, 2007-08-25 (Released:2009-11-12)

参考文献数

20

被引用文献数

3 6

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The cabinet office of the Japanese government demonstrated the prospects of future seismic hazards associated with a working model for possible earthquakes in the capital area of Japan. If this assumption is not unrealistic, it is reasonable to use this working model. However, it has already been reported that several active faults may exist in this area. This discrepancy can lead the assessment into unreal issue.I reveal the nature of the Ayasegawa fault located close to the capital area on the basis of geomorphic features. The fault extends in the NWSE direction for at least over 30 km, and the fault trace is linear, which is indicative of lateral movement. There is a graben structure delineated by the fault in the Minuma ward, Saitama City. The vertical component of the Ayasegawa fault is upthrown to the southwest and the average vertical slip rate is 0.05 to 0.1 m/ky. The netslip rate should be much larger than the vertical one, taking lateral movement into account. Although the single vertical offset is assumed to be 0.8 to 4 m, the rupture history of the fault remains unknown.The Ayasegawa fault is an southeastern extension of the Fukaya fault, and is composed of an active fault extending more than 120km through the Kanto Plain across the capital area of Japan. To prepare for a real seismic hazard and to try to reduce damage, we should check the properties and clarify the rupture history of these active faults as an urgent task. Precise local information on these active faults is necessary for motivating people to develop an awareness of disaster mitigation.

著者

Kunihiko ENDO Itsuki NAKABAYASHI Mitsuhisa WATANABE Fumio TSUNODA Hidehiko KAZAMA Jun-ichi YOSHINO Yasuhiro SUZUKI Hiroyuki SAKAUE Minoru SHIMIZU Hiroshi UNE

出版者

The Association of Japanese Geographers

雑誌

地理学評論 (ISSN:13479555)

巻号頁・発行日

vol.79, no.12, pp.738-743, 2006-10-01 (Released:2008-12-25)

被引用文献数

1 1

著者

Yasuhiro SUZUKI Hiroshi UNE Kunihiko ENDO Takehiko SUZUKI Itsuki NAKABAYASHI Kotaro YAMAGATA Ikuo SUZUKI Takashi SHIMURA Yoshiyuki MURAYAMA Takashi TODOKORO Itsuki NAKABAYASHI P. Hiroshi SATO Mitsuhisa WATANABE Yohta KUMAKI

出版者

The Association of Japanese Geographers

雑誌

地理学評論 (ISSN:13479555)

巻号頁・発行日

vol.78, no.12, pp.867-872, 2005-10-01 (Released:2008-12-25)

著者

Kaoru TANIGUCHI Mitsuhisa WATANABE Yasuhiro SUZUKI Hiroshi SAWA

出版者

SEISMOLOGICAL SOCIETY OF JAPAN

雑誌

Zisin (Journal of the Seismological Society of Japan. 2nd ser.) (ISSN:00371114)

巻号頁・発行日

vol.64, no.1, pp.11-21, 2011-08-25 (Released:2011-10-18)

参考文献数

28

被引用文献数

1 2

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The 150 km long Itoigawa-Shizuoka Tectonic Line Active Fault System (ISTL) in central Japan is one of the most active fault systems in Japan. Paleoseismologcal studies 1980s have revealed that the most recent event and the average recurence interval of the ISTL. The approximately 7 km long portion of the fault system between Matsumoto and Okaya has been regarded as a gap without any active fault trace. The gap namely the “Shiojiri Pass Gap” has long been taken as a segment boundary owing to the geometric discontinuity. Recent geomorphological analyses of the gap have demonstrated a through-going left-lateral slip assocaited with recent earthquakes in this area, based on aerial photograph interpretation and excavation studies. Excavation study on this portion revealed that the latest faulting event occurred between 1,700 cal. B.P. to 1,310 cal. B.P. (255 A.D. -645 A.D.). The timing of the last faulting event at this study area coincides with the timing in the Gofukuji fault and Okaya fault. The active faults extending from the Matsumoto basin as far as the northwestern margin of the Suwa basin display the evidence for its recent reactivation at the same time.