Observation of High Frequency Seismic Waves by Ocean-Bottom Hydrophones of a Submarine Cable System near the Northern Part of the Focal Region of the 1980 Izu-Hanto-Toho-Oki Earthquake (a Preliminary Report)
As reported in a preceding paper (Mogi and Mochizuki, 1980), an observation of high frequency seismic waves by a hydrophone on an observation ship was carried out just before and after the Izu-hanto-toho-oki earthquake of M6.7 on June 29, 1980 just above the focal region of this large submarine earthquake. About one thousand seismic events of high frequency waves were observed and some interesting results were obtained. Just after the hydrophone observation by the ship a continuous observation by ocean-bottom hydrophones of a submarine cable system was planned. Ocean-bottom hydrophones were located near the northern part of th,e focal region of the 1980 earthquake, 6.5 km distant from the east coast of the Izu Peninsula, because the northern region adjacent to the focal region of the 1980 earthquake seems to be a potential region for a future large earthquake (Mogi, 1981). A recording system for high frequency seismic waves is under construction. This ocean-bottom hydrophone observation system is now operating for conventional seismic observation in the low frequency range (less than 20 Hz). A number of earthquakes near the hydrophone station have been observed. Among them, three sets of a similar seismic wave-form were observed on October 7, 1981. A set of the seismic waves consists of two seismic shocks, that is, the pre-shock and the main-shock. The pre-shock is much smaller than the main-shock, and the magnitude of these shocks and the time intervals between the pre-shock and the main-shock are very similar in the three sets which occurred successively within 2 min. This shows that three earthquakes sets occurred by slips of exactly the same fault plane, that is, by the typical stick-slip mechanism.
雑誌名
東京大學地震研究所彙報 = Bulletin of the Earthquake Research Institute, University of Tokyo
巻
56
号
4
ページ
675 - 690
発行年
1982-03-31
ISSN
00408972
書誌レコードID
AN00162258
フォーマット
application/pdf
日本十進分類法
453
出版者
東京大学地震研究所
出版者別名
Earthquake Research Institute, University of Tokyo
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1980年伊豆半島東方沖地震の震源域北部での海底ケーブル方式ハイドロホンによる高周波地震動観測(序報)
ji0564004.pdf
(1.63MB)
