文献一覧: 渡辺偉夫 (著者)

1 0 0 0 OA 日本近海で発生した津波のマグニチュード決定式の地域性

著者: 渡辺偉夫
出版者: 公益社団法人日本地震学会
雑誌: 地震第2輯 (ISSN:00371114)
巻号頁・発行日: vol.48, no.2, pp.271-280, 1995-08-25 (Released:2010-03-11)
参考文献数: 14

Previous equation for the tsunami-magnitude scale after Abe (1981) has been re-examined using a more general form: M10=logA+a log Δ+b, where Mto is tsunami magnitude, A is the maximum double amplitude of tsunami as recorded on a tide gage, Δ is the shortest distance along oceanic path from the earthquake epicenter to a tide station, and a and b are constants. ABE (1981) used a=1 and b=5.55 in his determination of tsunami magnitude. This paper demonstrates, using more extensive sets of tide records, that the constants, a and b, vary regionally. For instance, a=0.86 and b=5.96 for tsunamis along the Pacific coasts in and around Japan, and a=0.52 and b=6.56 for tsunamis in the Japan Sea. These constants vary even in more regional scales and may depend on the submarine topography along a tsunami path. Renewed equations should be used for the determination of tsunami magnitude.

2022-07-02 07:49:22
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1 0 0 0 OA 震度分布による津波地震の一判別法日本付近における津波地震の分布

著者: 渡辺偉夫
出版者: 公益社団法人日本地震学会
雑誌: 地震第2輯 (ISSN:00371114)
巻号頁・発行日: vol.50, no.1, pp.29-36, 1997-05-28 (Released:2010-03-11)
参考文献数: 20

A method for judging tsunami earthquake is proposed. The method uses a simple formula for calculating the judging factor α from JMA seismic intensity and epicentral distance. α corresponds to the difference between the tsunami magnitude by WATANABE (1995) Mto and JMA earthquake magnitude MJ. [WATANABE (1994)]We apply this method to some recent and some historical tsunamigenic earthquakes around the Japan Islands. The results are as follows.1) Among 19 tsunami earthquakes, eight earthquakes have α values of 0.6 or more and one has α value of 0.5.2) The criterion α≥0.6 is suitable for identifying tsunami earthquake, because number of tsunami earthquakes of α≥0.6 is almost the same as the number of earthquakes of Mto-MJ≥0.6.3) Historical earthquakes of 1605, 1611 and 1677 were tsunami earthquakes. However, the earthquake of 1793 had a normal tsunami.4) Tsunami earthquakes around the Japan Islands are distributed along the Japan trench, off the southeast coast of Hokkaido and along the Nankai trough. It must be noticed that two tsunami earthquakes of 1611 and 1896 occurred off the Sanriku coast, and the two tsunami earthquakes occurred simultaneously in 1605 off the Kii peninsula and the Tokai coast.

2022-07-02 07:48:52
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1 0 0 0 OA 日本およびその周辺 (沖繩および南千島を含む) の津波の表

著者: 渡辺偉夫
出版者: 公益社団法人日本地震学会
雑誌: 地震第2輯 (ISSN:00371114)
巻号頁・発行日: vol.21, no.4, pp.293-313, 1969-02-25 (Released:2010-03-11)
参考文献数: 30
被引用文献数: 2

Table of tsunamis which occurred in and near Japan was prepared. The table consists of two parts. One part (Table 1) is the table of tsunamis caused by earthquakes, vocanic eruptions and landslides which occurred in and near Japan. Another one (Table 2) is the table of tsunamis which occurred in the Pacific Ocean and additionally invaded Japan and its vicinity.1) Table 1.The contents of the table are:a) Sequential numberb) Date in the Christian and Japanese Calendar (Time in Japanese Standard Time)c) Location of tsunami source or epicentral region together with longitude, latitude and depth of hypocenterd) Magnitude of earthquakee) Grade magnitude of tsunami by Dr. A. IMAMURA and Dr. K. IIDAf) Description of earthquake and tsunami.Magnitude of earthquake, and longitude, latitude and depth of hypocenter were taken from the “Rika-nenpyo (1968)”, the “Catalogue of major earthquakes which occurred in and near Japan, supplementary volume No. 1 (1958), No. 2 (1966) and No. 3 (1968)” and the “Zisin-geppo (1968)”.2) Table 2.The contents of the table are:a), c) and f) The same content as the Table 1b) Date in the Christian Calendar (Time in Greenwich Mean Time)e) Grade magnitude of tsunami occurred in the Pacific Ocean and invaded Japan and its vicinity.Magnitude of earthquake, and longitude, latitude and depth of hypocenter were taken from the “Seismicity of the Earth and Related phenomena (1954)” and the report of the U. S. Coast and Geodetic Survey.