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|タイトル: ||Matsushiro Earthquakes Observed with a Temporary Seismographic Network : Part 3.|
|その他のタイトル: ||臨時地震観測網による松代地震群の調査結果 : 第3報|
|著者: ||Party for Seismographic Observation of Matsushiro Earthquakes|
the Seismometrical Section, Earthquake Research Institute.
|掲載誌情報: ||東京大学地震研究所彙報. 第45冊第1号, 1967.6.15, pp. 197-223|
|抄録: ||The Matsushiro earthquake swarm commenced in August 1965, the activity reaching the first peak in November 1965, the second peak of the activity taking place in the period from March to May in 1966. Subsequently the daily frequency of earthquakes seemed to gradually decrease. However, the third peak of the activity occurred unexpectedly in the beginning of August 1966. The activity was most violent in August, the earthquakes with the intensity larger than IV on JMA scale occurring ten times in this month. Earthquakes with the intensity of IV occurred twice in the same day on 20th and 29th respectively. Earthquakes with the intensity larger than IV took place 7 times in September and 5 times in October 1966. The earthquake on 26th 03h 04m October was the greatest in magnitude among those which have occurred in this area since the beginning of the forementioned earthquake swarm. The magnitude of this earthquake was reported to be M=5.1 by JMA (Japan Meteorological Agency). Dwelling houses were partially damaged, cracks were created on the roads and stone-fences fell down in the villages near the epicenter. There was some damage to glass windows in the city of Nagano. In November 1966, no large earthquakes occurred and the frequency of small earthquakes also decreased. This paper will describe the observational results of the felt earthquakes during the period from September to November 1966 as the third report, following our previous papers. Members of the Institute who participated in the field observation were: T. Hagiwara, S. Saito, I. Karakama, M. Watanabe, T. Watanabe, T. Takahashi and Y. Maeda, the members of the Institute engaged in the interpretation and analysis of seismograms being: T. Hagiwara, T. Iwata, K. Makino, N. Kamata, M. Kino and Y. Miura.|
1965年8月に始った松代町附近の群発地震は,その年の11月に第1期とみられる地震活動があり, 1966年3月から5月には第2期の活動をむかえ,この期間が最もはげしく,その後,次第に減少するように見受けられたが, 8月に至って第3期の活動をむかえた.第3期活動の中心は8月で,震度IV以上の地震が10回起っている. 20日と29日には震度IVの地震が一日のうちに2回も発生した.