著者

河角 廣

出版者

東京大学地震研究所

雑誌

東京大學地震研究所彙報 = Bulletin of the Earthquake Research Institute, University of Tokyo (ISSN:00408972)

巻号頁・発行日

vol.29, no.3, pp.469-482, 1951-10-05

著者

河角 廣

出版者

東京大学地震研究所

雑誌

東京大學地震研究所彙報 (ISSN:00408972)

巻号頁・発行日

vol.29, no.3, pp.469-482, 1951-10-05

著者

羽鳥 徳太郎 片山 通子

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.52, no.1, pp.49-70, 1977-11-30

著者

岸上 冬彦 小坂 丈予

出版者

東京大学地震研究所

雑誌

東京大學地震研究所彙報 (ISSN:00408972)

巻号頁・発行日

vol.33, no.1, pp.153-161, 1955-06-25

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1953年7月26日箱根早雲山において山津波が発生し,人員及び建造物に対して相当の損害をあたえた(第1図).我々は7月29日, 31日, 8月5日及び11月11日に現地を調査する機会を得たので,その結果を報告する.

著者

中西 一郎

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.74, no.3/4, pp.301-310, 2000-03-30

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It is mentioned in several earthquake catalogues of historical earthquakes that two earthquakes occurred in May, 1685 and on October 3, 1686 in the Toyohashi region, central Japan. We have recently found historical documents recording the latter earthquake in the Toyohashi region where previous studies located the epicenter of the 1686 earthquake without documents. Our analysis of the documents suggests that the 1685 earthquake did not occur. The damage recorded in the historical documents on the 1686 earthquake was large in villages on the Pacific side of the Toyohashi region. According to this evidence we consider that the epicenter of the 1686 earthquake may be located near the Pacific coast to the south of the town of Toyohashi. This large earthquake, the magnitude of which is estimated to be about 7, occurred 21 years before the great Hoei earthquake of October 28, 1707 (M=8.4). In the eastern part of Aichi prefecture, including the Toyohashi region and the offshore region of the Atsumi peninsula, moderate earthquakes have recently occurred. It is possible that the 1686 earthquake was a seismic precursor to the great 1707 earthquake. The eastern part of Aichi prefecture and the offshore region of the Atsumi peninsula in Aichi prefecture may be regions where we should carefully observe seismic activity, and other geophysical and geochemical phenomena.

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.52, no.3/4, pp.407-439, 1978-03-31

著者

宇佐美 龍夫 茅野 一郎

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.48, no.5, pp.923-933, 1970-12-05

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The relation between Mk and MJ MJ=0.5Mk+4.35 is obtained by the method of least squares, using data from 1926 to 1943. It is shown that the relation can also be applied to earthquakes between 1885-1925. However, for earthquakes before 1885, the relation seems to hold for only large earthquakes with magnitude M(=0.5 Mk+4.85) larger than 8.0. MJ of the great Kanto earthquake of 1923 is given as 7.83 from the seismograms recorded at 3 Japanese stations.

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

宇佐美 龍夫 茅野 一郎

出版者

東京大学地震研究所

雑誌

東京大學地震研究所彙報 = Bulletin of the Earthquake Research Institute, University of Tokyo (ISSN:00408972)

巻号頁・発行日

vol.48, no.5, pp.923-933, 1970-12-05

---

The relation between Mk and MJ MJ=0.5Mk+4.35 is obtained by the method of least squares, using data from 1926 to 1943. It is shown that the relation can also be applied to earthquakes between 1885-1925. However, for earthquakes before 1885, the relation seems to hold for only large earthquakes with magnitude M(=0.5 Mk+4.85) larger than 8.0. MJ of the great Kanto earthquake of 1923 is given as 7.83 from the seismograms recorded at 3 Japanese stations.

著者

相田 勇

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.56, no.2, pp.367-390, 1981-09-30

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地震断層モデルを波源とする津波数値実験が,東海道沖においても有用であることは,1944年東南海津波の例によって認められた.ここでは数値実験によって,1854年安政東海津波,1707年宝永津波,1605年慶長津波,1498年明応津波の波源断層モデルのパラメータを求めた.いずれも東海道に問題を限って議論される.この中,安政,宝永津波については,かなり信頼度の高いモデルが確定された.しかし慶長,明応津波については,史料の乏しいことなどもあって,信頼度が低いことは否めない.これらの津波の特徴を比較すると,地域によっては明応津波が最も高く,災害予測の面から見落すことのできない津波であると考えられる.また局地モデルによる清水港の陸上遡上計算の結果,防波堤,埋立地などの港湾工事が,津波の高さを軽減するのにかなり効果を持っていることがわかった.また津波危険度の局地性についても,計算上の結果が得られた.

著者

相田 勇

出版者

東京大学地震研究所

雑誌

東京大學地震研究所彙報 = Bulletin of the Earthquake Research Institute, University of Tokyo (ISSN:00408972)

巻号頁・発行日

vol.56, no.2, pp.367-390, 1981-09-30

---

地震断層モデルを波源とする津波数値実験が,東海道沖においても有用であることは,1944年東南海津波の例によって認められた.ここでは数値実験によって,1854年安政東海津波,1707年宝永津波,1605年慶長津波,1498年明応津波の波源断層モデルのパラメータを求めた.いずれも東海道に問題を限って議論される.この中,安政,宝永津波については,かなり信頼度の高いモデルが確定された.しかし慶長,明応津波については,史料の乏しいことなどもあって,信頼度が低いことは否めない.これらの津波の特徴を比較すると,地域によっては明応津波が最も高く,災害予測の面から見落すことのできない津波であると考えられる.また局地モデルによる清水港の陸上遡上計算の結果,防波堤,埋立地などの港湾工事が,津波の高さを軽減するのにかなり効果を持っていることがわかった.また津波危険度の局地性についても,計算上の結果が得られた.

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

NAKAMURA Kazuaki

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.42, no.4, pp.649-728, 1965-03-15

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Oshima Volcano is a basaltic, insular stratovolcano with a summit caldera within which lies an active cone Mihara-yama. Izu- Oshima island is situated on the northern part of a volcanic chain extending from central Honshu to Marianas. Oshima Volcano consists an essential part of Izu-Oshima island which is the largest of the seven Izu-islands, being 92km2 in area and 22.5km3 in volume above sea-level. Volcanic products of the volcano were studied stratigraphically. The method and results of the study are summarized and discussed in this paper. A group of erupted material, including lava-flows, scoria- andash-falls, which successively accumulated without any weatheringbreak is called a member in this paper. A member is the basic stratigraphic unit which is proved to be the product of a singleeruptive cycle. Within a member, there is a definite succession oferupted material, scoria-falls→lava-flows→alternation of ash-falls in ascending order. The time needed for the deposition of amember is considered to be 10 years or less from an examinationof the latest two records of major eruption(1777~1792 and 1684~1690). The time needed for the deposition of the basal scoria of amember is far shorter than that for the deposition of the alternating ash-falls. This is evidenced partly by the examination of historical documents and partly by the simple elliptic shape of the distribution of the basal scoria. Eruptive activity represented bya member may be a continuous process in which the magma in the central conduit rises with explosive eruptions of scoria, overflows and then gradually falls with an ejection of ash formany years. Oshima Volcano is composed of more than a hundred members. The youngest twelve members are lumped into the Younger Oshima Group, with which this paper is chiefly concerned. Dates of the deposition of the twelve members are inferred bythe correlation with historical documents and excavated fragmentalpottery remains and by radiocarbon measurements. As a result, the Younger Oshima Group is found to consist of the deposits during the last 1500 years or so, and the deposition of each member, in other words .major eruption, to have taken place periodically with an interval of about 135±50 years. The volume of individual members is calculated to range from 0.1 to 0.7km3. The volume of the Younger Oshima Group is estimated to be 3.6km3, of which only 0.7km3 is now accumulated on the slope of the main cone. The rest is the caldera fill (ca. 2.2km3) and the deposits outside the island. The explosion index is calculated to be, about 60 for the Younger Oshima Group. Thermal energy transported by the Younger Oshima Group attains to the order of 1×1026 erg and the rate of energy release is 8.7~6.0×1024 erg/100 years. More than forty parasitic volcanoes are distributed within two narrow fracture zones. They are monogenetic, that is, the entire erupted material of each is incorporated within a single member. The summit caldera was formed after the deposition of the twelveth member(S2) from the surface and prior to that of the tenth member(N4), or some fourteen centuries ago. The volume of the twelveth and the eleventh member(S2 and S1), which are considered to have deposited just before the caldera formation, is estimated to be 0.4km3 i. e. one-eighth of the volume of the decapitated summit(3.1km3). These are mainly steam explosion breccias and ash-falls with accretionary lapilli. This will indicate that the summit was engulfed associated with intense explosions. The actual course of the engulfment is inferred to be like the eruption of Kilauea in 1924, after a consideration of the similarity of the sequence of events for the both activities. Recent eruptions of Oshima Volcano after the last major activity(1777~1792, the product of which is the uppermost member Y1), are very different in nature from those represented by members. Recent eruptions are more effusive(explosion index 10±), smaller in the volume of erupted material(less than 0.03km3) and have affected only the interior of the caldera or even of the crater of Mihara-yama. The rate of thermal energy release is also lower(2.7×1024 erg/100 years). Moreover, the period after the last major activity is that of repose judging from the deposits on the slope of the main cone.

著者

早川 由紀夫

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.507-592, 1986-03-31

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The eruptive activity of Towada Volcano is documented by the tephrostratigraphic study. More than 20 eruptive episodes are described in detail with isopach maps and isograde maps of maximum pumice size, maximum lithic size, and median diameter for the individual fallout deposits. The activity of the volcano started about 200,000 years ago along the NE-SW trending line crossing the present lake Towadako and relatively small-scale volcanoes were formed. A caldera 11km×11km wide was formed as a result of several eruptive episodes during the period about 55,000 to 13,000 years ago, three of which included voluminous pyroclastic flow eruptions. The post-caldera activity occured at a rate of one eruptive episode every 1,000 to 2,000 years and a stratovolcano and two lava domes were formed in the caldera. The latest eruptive episode was dated 1,250 y B. P. by the radiocarbon method. Rocks of Towada Volcano cover a wide range from basaltic andesite to rhyodacite (SiO2 : 51-70wt.%) with phenocrysts of plagioclase, augite, hypersthene, and magnetite with occasional olivine. Horn-blende is characteristically found in the pyroclastic deposits of 13,000 years old and in some earlier deposits. Volumes, V, of two plinian deposits are determined by the crystal method : 6.7km3 for the Chuseri deposit and 2.2km3 for the Nambu deposit. Then an empirical formula, V=12.2 TS, is obtained for the practical volume estimation, where T is the thickness of an isopach and S is the area enclosed by the isopach. Application of the formula to the fallout deposits of Towada Volcano suggests that the total magma erupted during the past 55,000 years amounts to 1.5×1017g. This corresponds to the discharge rate of dense rock equivalent to 1.1km3 per thousand years. The cross-wind range, Rc, of the pyroclasts of a given size may be a good indicator of the maximum height reached by the pyroclasts in the eruption column. It is found that the Rc is relatively large for those deposits whose erupted masses are relatively large. The dispersal of a fallout deposit is also seriously affected by winds. A plausible solution of the eruption condition for the Nambu deposit is that 4mm size lithic fragments reached the maximum height of 15km in the eruption column, then they were detached from the column and displaced by winds having an average velocity of 30m/s. After a 20 min flight, they fell upon the ground 48km east of the source. Whole-deposit grain size populations are determined for the Chuseri and Nambu plinian deposits. The Chuseri population is similar to the New Zealand examples. However, the Nambu population is distinctly coarser than the others.

著者

宍倉 正展

出版者

東京大学地震研究所

雑誌

地震研究所彙報 (ISSN:00408972)

巻号頁・発行日

vol.78, no.3, pp.245-254, 2003

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A tectonic geomorphological study is one of the best methods of evaluating the timing and the crustal deformation of pre-historic earthquake. To reveal the cycle of interplate earthquakes along the Sagami Trough, I investigatedthe emergedshoreline topography andthe fossilizedsessile assemblages in the Miura Peninsula andthe Boso Peninsula. The distribution pattern of coseismic vertical displacement during the 1703 Genroku Kanto Earthquake inferredfrom the height distribution of the paleo-shoreline suggests that the fault source model consists of a dual fault system of the Fault A andB. Fault A is also the source of the 1923 Taisho Kanto Earthquake. The geometry and ages of the emerged shoreline topography divided into several levels indicate that the characteristic earthquake generatedfrom Fault A has occurredabout every 400 years. One of several events, it is accompaniedwith a slip of Fault B, which has a recurrence interval of 2000-2700 years.

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.2, pp.171-185, 1976-01-30

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

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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

都司 嘉宣 日野 貴之

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.68, no.2, pp.91-176, 1993-09-30

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寛政4年4月1日(1792年)に,普賢岳の火山活動の終期に島原市付近に生じた地震に誘発された島原半島眉山の東斜面の崩壊によって,多量の土砂が有明海に流入し,有明海に大きな津波を生じた.この津波によって,島原半島側と,対岸の熊本県側の海岸は大きな津波被害を被った.近年,このときの熊本県側の津波被害の状況を伝える文書が数多く発掘された.この研究では,津波による死者数,家屋被害,田畑の浸水範囲と面積を確定し,あわせて被災現地での伝承,津波の浸水限界を示す「津波留石」などの知識を加えて,津波の浸水高の測定を行った.この津波による,肥後国の被害は,武士僧侶を除く死者が玉名郡で2,221人,飽田郡で1,166人,宇土郡で1,221人で肥後3郡合計で4,653人.このほかに武士僧侶とその家族たち162人を加え,4,815人が肥後三郡の死者総数となる.また,大矢野島を含む天草諸島では343人で,結局現在の熊本県がわ海岸全体で5,158人の死者があったものと見積られる.肥後三郡のけが人は811人,流失破損家屋2,252軒,浸水田畑3,848町歩であった.津波高さは熊本市の河内,塩屋,近津付近で15mから20mに達し,また三角半島北岸の細田,大田尾などで高く,三角町大田尾で22.5mに達した.

著者

石原 吉明 束田 進也 酒井 慎一 平松 良浩 古本 宗充

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.76, no.1, pp.87-92, 2001-07-25

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Fireballs, which are caused by high-velocity passages of meteorites through the atmosphere, generate shock waves. It has been known that such shock waves are often recorded on seismograms. It is possible to determine the trajectories and the sizes of a fireball using seismological records. We have searched shock wave signals from many bright fireballs observed in the period from September 1996 to November 1998, and the 1999 Kobe meteorite. The shock waves from one large fireball, which is called the Miyako fireball, and the Kobe meteorite are clearly recorded on many seismograms. In particular, the shock waves from the former fireball are widely recorded by the dense seismic array of 1997-98 joint seismic observations in the Tohoku Backbone Range. We determine their trajectories. Amplitudes of the shock waves are found to be possibly correlated with the masses of the meteorites. It is also indicated that the shock waves from fireballs, which are darker than brightness magnitude -10, are too weak to be recognized on the seismograms of ordinary seismic stations in Japan.

著者

河角 広

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.29, no.3, pp.469-482, 1951-09

被引用文献数

6