著者
羽鳥 徳太郎
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.29, no.4, pp.355-363, 1976-12-15 (Released:2010-03-11)
参考文献数
5
被引用文献数
2 2

The Kalapana tsunami was generated off the south coast of Hawaii Island, accompanying the earthquake of magnitude Ms=7.2 (NOAA), at 14h 48m (GMT), Nov. 29, 1975. Some features of this tsunami are investigated on the basis of tide gauge records of NOAA and Japan, adding the reports of the US field investigation.Tsunami magnitude of the Imamura-Iida scale is decided as m=2, judging from the tsunami heights observed near and distant fields. The initial motion of the tsunami waves was in an upward direction at the whole Hawaiian stations, suggesting the uplift of the sea-bottom in the tsunami source area. The source dimension of tsunami is inferred to be 70km along the south coast of Hawaii Island, and the area is 2.2×103km2. By applying the corrections for the refraction and shoaling from the inundation heights at the Hawaii Island, the average vertical displacement of 1.2m would be occurred in the source area. The tsunami energy of approximately is 1.6×1020 ergs. According to statistical relation, the present tsunami is large compared with the earthquake magnitude.The tsunami fronts arrived in NE Japan at about 7h 40m after the occurrence of the earthquake. The maximum double amplitude is 20-30cm with the period of about 15min and the amplitude is relatively higher than that in SW Japan. It is noticed that the wave rays emitting the tsunami source concentrate in the Kuril Islands.
著者
羽鳥 徳太郎
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.43, no.2, pp.227-232, 1990-06-24 (Released:2010-03-11)
参考文献数
17
被引用文献数
5 5

It is reported by an old document that the Yamagata-Oki earthquake of Dec. 7, 1833 (Oct. 26, Tenpo 4), hitting the Yamagata, Niigata and Akita districts destroyed 475 houses in the Shonai plain and the tsunami killed about 150 persons. In this paper the distributions of the seismic intensity and the tsunami behavior along the Japan Sea coast are investigated with an addition of newly collected data. The magnitudes of earthquake and tsunami are compared with those of the 1964 Niigata and the 1983 Japan Sea earthquakes. The results are summarized as follows:1) According to the intensity-distance diagram, the earthquake, magnitude is inferred as M=7.5, because the same intensity area is smaller than that of the 1983 Japan Sea earthquake and similar to that of the 1964 Niigata earthquake.2) By judging from the tsunami height-distance diagram (HATORI, 1986), tsunami magnitude on the Imamura-Iida scale is m=2.5, which are somewhat larger than the former value. Extraordinary run-up heights at Wajima (tip of Noto peninsula) and Oki Islands located in far field may be caused by the refractive effect and the reflected waves from the continental coasts.
著者
羽鳥 徳太郎
出版者
東京大学地震研究所
雑誌
東京大学地震研究所彙報 (ISSN:00408972)
巻号頁・発行日
vol.60, no.1, pp.p87-95, 1985

1984月6年13日,鳥島近海地震(M=5.9)によって,伊豆諸島をはじめ,房総から四国に至る沿岸各地の検潮所で全振幅10~57cm,周期5~9分の津波が観測された.また,八丈島の八重根漁港では,最大波の全振幅130~150cmの津波が目撃された.検潮記録によれば,津波マグニチュードはm=0と格付けされ,地震規模に対して津波が異常に大きい"津波地震"であった.波源域は須美寿島(八丈島南方190km)西側の水深1,000mの伊豆・小笠原海嶺にあり,波源域の長さは25kmと推定される.津波初動の押し引き分布から判断して,波源の西側の海底が隆起し,東側が沈降したとみなされる.
著者
羽鳥 徳太郎
出版者
東京大学地震研究所
雑誌
東京大学地震研究所彙報 (ISSN:00408972)
巻号頁・発行日
vol.60, no.1, pp.87-95, 1985-09-05

1984月6年13日,鳥島近海地震(M=5.9)によって,伊豆諸島をはじめ,房総から四国に至る沿岸各地の検潮所で全振幅10~57cm,周期5~9分の津波が観測された.また,八丈島の八重根漁港では,最大波の全振幅130~150cmの津波が目撃された.検潮記録によれば,津波マグニチュードはm=0と格付けされ,地震規模に対して津波が異常に大きい“津波地震”であった.波源域は須美寿島(八丈島南方190km)西側の水深1,000mの伊豆・小笠原海嶺にあり,波源域の長さは25kmと推定される.津波初動の押し引き分布から判断して,波源の西側の海底が隆起し,東側が沈降したとみなされる.
著者
羽鳥 徳太郎
出版者
東京大学地震研究所
雑誌
東京大学地震研究所彙報 (ISSN:00408972)
巻号頁・発行日
vol.60, no.4, pp.p643-655, 1985

1985年3月3日,チリのバルパライソ沖でおきた地震(M=7.8)により,約23時間後に日本の太平洋沿岸各地の検潮所で全振幅10~30cmの津波が観測された.太平洋各地の検潮記録から判定すれば,津波マグニチュードはm=1.5と格付けされる.日本沿岸では津波の周期15分が卓越したが,最大波に60分の長周期波も含まれている.津波初動から最大波が現われた時間は,3時間と7時間前後のところがあり,3時間後に最大波を記録した1960年チリ津波の波形パターンと多少異なった.1700年以降の日本の記録によれば,チリでM8以上の巨大地震が発生して,チリ沿岸で波高が6~8mの場合,日本沿岸では1m程度の波高になり,10mをこえると日本では3m以上に達して被害をもたらした.また,ハワイでは常に日本より波高が大きい.これは,日本の津波予報を適確に判断する上で,チリおよびハワイの津波情報がきわめて重要であることを示している.
著者
羽鳥 徳太郎
出版者
東京大学地震研究所
雑誌
東京大学地震研究所彙報 (ISSN:00408972)
巻号頁・発行日
vol.62, no.3, pp.p297-309, 1988-01

寛政5年1月7日(1793年2月17日)宮城沖に発生した地震の震度分布およびそれに伴う津波の高さを,新史料をもとに調べ,近年の宮城沖地震との比較から地震と津波の規模および波源域を考察した.各地の史料を調べた結果,震度5の範囲は岩手県中部から福島県北部に至る内陸部に分布し,震度4の範囲は東北地方から関東地方に広くまたがることが示された.1933年三陸地震・1978年宮城県沖地震などの震度分布との比較から,寛政地震のマグニチュードはM=7.8と推定された.一方,この地震に伴う津波の高さは,岩手県中部~牡鹿半島沿岸で3~5m,福島県沿岸では2~3mと推定された.筆者の方法(羽鳥,1986)によれば,津波マグュチュード(今村・飯田スケール)はm=2.5と見つもられ(1968年十勝沖津波と同じ規模),従来推定されていた値よりもやや大きい.震度および津波の高さの分布から,波源域は1897年8月の宮城沖津波の波源域を含むかたちで海溝付近にあり,長さ200km,幅80km程度の大きさであったと考えられる.The Miyagi-Oki tsunamigenic earthquake of Feb. 17, 1793 (Jan. 7, Kansei 5) hit the Tohoku district, and its aftershock activity continued for a long time. According to the old documents, in the Sendai region 12 persons were killed and 1060 houses were destroyed by the earthquake. Along the Pacific coast from Aomori to Fukushima 22 or more persons were drowned and about 500 houses and many ships were damaged by the tsunami. In this paper the distributions of the seismic intensity and tsunami behavior are investigated with the addition of newly collected data. The results are summarized as follows: 1) A seismic intensity of 5 (JMA scale) occurred inland for 230 km from Morioka to Fukushima, and an intensity of 4 was widely distributed in the Tohoku to Kanto districts. The earthquake magnitude is inferred as M=7.8 via a comparison with the seismic intensity pattern of other Miyagi-Oki earthquakes. The epicenter is estimated to have been 38.5°N, 143.5°E near the trench. 2) Considering the ground level of the damaged regions, the tsunami heights were inferred to have been three meters (above M.S.L.) along the Iwate to Miyagi coasts and locally to have reached 4~5 meters. The tsunami heights along the Fukushima coast were 2~3 meters. The head of the large bay with seiche periods of 30min or more was con- spicuously damaged, suggesting that the longperiod waves were predominant. By use of the author's method based on the classification of tsunami heights along the coast, the tsunami magnitude (Imamura-Iida scale) is determined as being m=2.5. 3) The estimated source area is lapped on the tsunami source of Aug. 5, 1897, lies near the trench. According to the statistical relation of tsunami magnitude, the source area may be 80×200 km2. It is pointed out by many seismologists that a seismic gap exists near the trench far east of Miyagi Prefecture. For future tsunamis generated in this region, the behaviors of the 1793 tsunami suggest useful information.
著者
羽鳥 徳太郎
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.29, no.2, pp.179-190, 1976-05-15 (Released:2010-03-11)
参考文献数
12

The source mechanisms of eight tsunamis generated off Fukushima, the Pacific side of northeast Japan, in May to November 1938 are re-studied, making use of tide gauge records. The source areas for each tsunami inferred from the inverse refraction diagrams are shown in the bathymetric charts. The source locations moved to the north direction along the continental shelf, and the north end was in contact with the source area of the tsunami at Nov. 3, 1936. Among these tsunamis, three tsunamis were recorded in a downward direction at Onahama located near the sources, but other tsunamis began with an upward motion. According to the seismic wave data, the tsunamis of downward and upward initial motions correspond to the normal and reverse fault earthquakes, respectively. Tsunamis accompanied by earthquake of the normal fault type were generated later than those for the reverce fault earthquakes, and these source areas are located in the deep sea-bottom side. The source lengths of tsunami are 60-130km, corresponding to earthquake magnitude. A whole length from north to south ends of the sources is 200km.The calculated sea-level disturbances at the sources for each tsunami are in the range of 10-50cm which the heights nearly agree with the seismic fault models. The whole volume of the displaced water in the tsunami sources is 13×1015cm3 which is comparable to that of the 1968 Tokachi-oki tsunami (tsunami magnitude of Imamura-Iida scale m=2.5).
著者
羽鳥 徳太郎
出版者
東京大学地震研究所
雑誌
東京大学地震研究所彙報 (ISSN:00408972)
巻号頁・発行日
vol.60, no.3, pp.429-438, 1986-02-07

津波史料をもとに別府湾沿岸を現地調査し,地盤高をふまえて各地の津波の高さ(平均海面上)や浸水域の広がりを検討した.大分市内では,流失した寺院の分布から津波の高さは4~5.5mに推定され,地盤高ぶおよそ4m以内の範囲が浸水域とみなされる.別府湾口の奈多と佐賀関ではそれぞれ7~8mと6~7mの波高に達し,湾外の上浦で4m,臼杵では3~4mと推定される.津波マグニチュードは今村・飯田スケールでm=2と格付けされる.津波・震度分布および周辺のテクトニクスから判断すれば,波源域は別府湾を包み東西方向に50km程度の長さがあったと推定される.また,瓜生島・神場洲の地盤沈降の記録は別府湾が陥没したことを暗示し,高角正断層の地震により津波が発生したと考える.
著者
羽鳥 徳太郎
出版者
東京大学地震研究所
雑誌
東京大学地震研究所彙報 (ISSN:00408972)
巻号頁・発行日
vol.50, no.4, pp.397-414, 1976-03-31
著者
羽鳥 徳太郎
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.41, no.2, pp.215-221, 1988-06-25 (Released:2010-03-11)
参考文献数
12
被引用文献数
1 2

Three Nankaido earthquakes which occurred near the Nankai Trough in 1707 (Hoei 4), 1854 (Ansei 1) and 1946 (Showa 21) hit the West Japan and the Wakayama, Tokushima and Kochi coasts, facing the Pacific Ocean, have suffered severe damage from large tsunamis. Inundation heights along these coasts were surveyed by the author (HATORI, 1978, 1980, 1981). In this paper, we investigate the tsunami behaviors in the Seto Inland Sea and Bungo Channel on the basis of newly collected documents. The obtained results are as follows:1) Inundation heights (above M. S. L.) of the 1946 tsunami at the coasts facing the Bungo Channel were 1-3 meters, and heights at the south region of channel were large. The inundation heights of the 1707 Hoei and 1854 Ansei tsunamis have reached 3-4 meters.2) According to the refraction diagram of the 1946 tsunami, the wave-fronts propagated into the Seto Inland Sea through the Kii and Bungo Channels meet the central part about 3 hours after the earthquake occerrence. The inundation heights about 1 meter were uniformly distributed.3) The inundation heights of the 1707 Hoei and 1854 Ansei tsunamis in the western to central parts of the Seto Inland Sea were about 1.5 meters, but those in the eastern part were 2-3 meters. This behavior seems to be caused by the differences of tsunami heights between both channls and the propagated distances. For each Nankaido tsunami, the inundation heights along the coasts facing the Kii Channel were 1-2 meters larger than those of the Bungo Channel.Althogh tsunami heights in the Seto Inland Sea were small compared with those of the Pacific side, many salt fields along the coast were damaged both by earthquakes and tsunamis. Further more, velocity of the tidal current was locally fast, and many sailors were shipwrecked in straits of the Inland Sea. In future, it is indispensable to take precautions against the effect of tidal currents.
著者
羽鳥 徳太郎
出版者
東京大学地震研究所
雑誌
東京大学地震研究所彙報 (ISSN:00408972)
巻号頁・発行日
vol.60, no.3, pp.p429-438, 1985
被引用文献数
1

津波史料をもとに別府湾沿岸を現地調査し,地盤高をふまえて各地の津波の高さ(平均海面上)や浸水域の広がりを検討した.大分市内では,流失した寺院の分布から津波の高さは4~5.5mに推定され,地盤高ぶおよそ4m以内の範囲が浸水域とみなされる.別府湾口の奈多と佐賀関ではそれぞれ7~8mと6~7mの波高に達し,湾外の上浦で4m,臼杵では3~4mと推定される.津波マグニチュードは今村・飯田スケールでm=2と格付けされる.津波・震度分布および周辺のテクトニクスから判断すれば,波源域は別府湾を包み東西方向に50km程度の長さがあったと推定される.また,瓜生島・神場洲の地盤沈降の記録は別府湾が陥没したことを暗示し,高角正断層の地震により津波が発生したと考える.
著者
羽鳥 徳太郎
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.49, no.4, pp.461-466, 1997-03-14 (Released:2010-03-11)
参考文献数
8

A small tsunami accompanied with the Hyogoken-Nanbu earthquake on January 17, 1995 (epicenter: 34°36′N, 135°03′E, d=14km, M=7.2, JMA), was observed at many tidal stations around the source area. The maximum double amplitude at Ei, Awaji Island, reached 68cm, and those at most Stations were 10-20cm or less with the wave period of 10-20min. By judging from the diagram of the attenuation of wave-height with distance, tsunami magnitude on the Imamura-Iida scale was determined to be m=-2, which is smaller by two grades (amplitude: 1/5 less) than those generated by earthquakes of the same magnitudes, because the seismic faults lay on land. The size of the source area estimated by means of an inverse refraction diagram is 70×13km2 extending NE-SW direction from the Hanshin region to the western area of Awaji Island. The tsunami source comprehends the aftershock area. Considering the distribution of the initial motions of tsunami observed by tidegauges, it suggests that the sea-bottom on the east side of the northern tsunami source (the northern part of Osaka Bay) was uplifted and that on the west side (Harima-Nada Sea) was subsided.