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タイトル: 6. 昭和20年1月13日三河地震餘震觀測(序報)
その他のタイトル: 6. A Preliminary Report on the Aftershocks of the Mikawa Earthquake
著者: 表, 俊一郎
著者(別言語): Omote, Syun'itiro
発行日: 1948年6月30日
出版者: 東京大学地震研究所
掲載誌情報: 東京大學地震研究所彙報. 第24冊第1/4号, 1948.6.30, pp.77-86
抄録: The Mikawa district, the southern part of Aiti Prefecture, was attacked by a violent shock at the midnight of January 13, 1945, with the result more than 2,000 people were killed and about 5,000 houses destroyed. Following the main shock a great many aftershocks were felt. The present writer hurried to the place, carrying with him nine seismographs, four of which were displacement seismographs of the inverted pendulum type with their oscillation period adjusted at about 6 seconds, and the remaining five were short-period acceleration seismometers of the portable type. These acceleration seismometers were installed temporarily at 4 places, i.e., Gamagori, Yosida, Anzyo and Handa. Observation was started on Feb. 10 and was continued until the end of March. The present report is concerned with fourteen rather noticeable earthquakes that had been recorded by the seismographs at the four stations by Feb. 28. The values of Omori's constant κ obtained from these earthquakes were about 4 or 5 as shown in Table I. Epicenters were determined as in Fig.1. Accompanying the main shock a conspicuous fault presented itself, and upheavals and subsidences of the shore lines were distinctly noticed. These topographic changes will be clear in Fig.2. It will be seen, however, that the epicenters of the aftershocks were not distributed in the heaved-up regions only. About a month previous to this earthquake, on December 7, 1944, there had been another very great earthquake, which had caused severe damages to this same district. On that occasion the down-town part of the Handa City was badly devastated, while in the up-town part the damages were rather slight. Two temporary observation points were selected, one up town and one down town, and each of them was equipped with two displacement seis-mographs of E-W and N-S components and one accelograph. Brief analyses were made of the records obtained at these two observation stations, with the result shown in Figs.6 and 7. We notice that the predominant period of the seismic waves recorded at the station in the down-town part is decidedly longer than that of the up-town one.
URI: http://hdl.handle.net/2261/10632
ISSN: 00408972


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