著者

池上 良平

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.34, pp.37-72, 1981

被引用文献数

1

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.48, no.1, pp.91-97, 1995-05-25 (Released:2010-03-11)

参考文献数

8

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Accompanied with the Guam earthquake on Aug. 8, 1993 (epicenter: 13.0°N, 144.7°E, d=61km, Ms=8.0, USGS), a tsunami was observed at many tidal stations in Japan. Tsunami magnitude and the behavior of propagation are investigated, comparing with those of the 1990 Saipan tsunami (m=2). The travel times in West Japan were about 3.5 hours. The maximum double amplitude at Muroto and Tosa-Shimizu near the tip of peninsula reached 84cm with the wave-period of 8 minutes, and those in the Ryukyu Islands were relatively small. The distribution pattan of wave-heights is similar to that of the 1990 Saipan tsunami. By judging from the diagram of the attenuation of wave-height with distance, the tsunami magnitude on the Imamura-Iida scale was determined to be m=2.5. Although wave-heights of the present tsunami are about 1.5 times higher than those of the 1990 Saipan tsunami, the magnitude value is normal compared to earthquake with similar size in other regions.

著者

瀬野 徹三

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.61, pp.357-364, 2009

被引用文献数

2

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History of studies of intraslab seismicity and its generation mechanisms, since the work by Wadati, is reviewed. Through the initial stage of studies of morphology of the intraslab seismicity, there followed the stage of discussion of focal mechanisms and terminal depths by mechanics and temperature of the slab. In 1970s, double seismic zones were discovered and their generation mechanisms were discussed in terms of bending or thermal stresses. In recent years, to overcome a difficulty that very high pressure prevents intraslab seismicity, dehydration embrittlement and phase transformation have been invoked for the mechanisms of intermediate and deep earthquakes, respectively. If the intermediate seismicity represents dehydration, it may give us a key to understand the distribution of fluids to the upper plate and to the seismogenic interplate thrusts, and finally to understand tectonics and volcanism in subduction zones.

著者

和達 清夫

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.34, pp.180-184, 1981

被引用文献数

1

著者

湯村 哲男 広野 卓蔵 和達 清夫

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.23, no.2, pp.99-121, 1970

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Spatial distribution of earthquake foci for the period from 1926 to 1968 in and near Japan were expressed in 16 maps each for a layer of 20-40km in thickness lying between 0 to 600km in depth. The maps show definitely the boundary lines and centers of local activities distinguishable in seismicity from each other. We named them seismic blocks. The centers of the shallow seismic blocks which crowd in a zone along the west side of the Japan trench can be traced down to 600km in depth. At first such centers move with increasing depth toward two junction areas of the island arcs of Kuril, NE-Japan and Izu-Bonin, that is, the Hokkaido and the Kwanto districts. From there they continue sinking to north for Hokkaido and to west for Kwanto making a dipping angle of 30°. Then their directions change abruptly by 90° at a depth of about 300km. From North Hokkaido one branch of the locus of the center goes into the Okhotsk Sea and the other into the Japan Sea along the coast of Primorye. On the other hand, the locus of the block center moving toward the west Kwanto turns to the south at that depth under Gifu Pref. for the Shikoku Basin, although a shorter branch goes northward into the Japan Sea. It is notable that few deep shocks occur in the middle of the Japan Sea. Considering the other geophysical and geological phenomena such as (1) the negative zone of isostatic anomaly of gravity lying along the Japan trench branches out to the junction areas in land, (2) the movement of the triangulation stations for the last 60 years or so amounts to about 3m to the north at Aomori Pref. in comparison with the Kui Peninsula, showing that two forces are acting in the respective areas in opposite directions, (3) the axis of mountain ranges made of metamorphic rocks which encounter the locus of the block center in Hokkaido and Central Honshu underwent severer bending, we conclude that the locus of the seismic block center expresses the location of the mantle current coming from the Pacific. itself.

著者

和達 清夫

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.4, no.5, pp.265-270, 1932

著者

和達 清夫 高橋 末雄

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.27, no.1, pp.42-56, 1974

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In the present paper the underground structure peculiar to Japan and its neighborhood is dealt with, based on the seismic activity in Japan and neighborhood, especially taking account of the fact that each of the seismic activity area and the seismic inactivity area shows in the subterranean space its respective space, and adding the authors' investigational result to the fruits of researches hitherto.<br>Main results of the present paper are:<br>(1) The seismic activity area was divided into 3 zones: the shallow earthquake zone (particularly the existence of &ldquo;a thick shallow earthquake zone&rdquo;), the joint earthquake zone and the deep earthquake zone.<br>(2) A concept that the seismic activity zone can be regarded as &ldquo;the crust&rdquo; has been proposed.<br>(3) From the discussion of the travel time residual and the area of abnormal distribution of seismic intensities, the values of Low <i>V</i> and Low <i>Q</i> of the seismic inactivity area were obtained, and in particular the stronger point of that property was found at a comparatively small depth in the underground on the continental side along the volcanic front.<br>(4) The mantle flow in Japan and neighborhood is assumed to be composed of its main flow (along the deep earthquake zone) which flows descending from the Pacific side to the continental side and from east to west, of a weak flow northward in the offing of Tosa and in Enshu-nada, and of flows eastward and southward from the direction of the Sea of Japan.<br>(5) In general, where the mantle flow ascends, there exist Low <i>V</i> and Low <i>Q</i> and the area is related to volcanic activities, and where the flow descends, the area is related to the seismic activity area.<br>(6) The joint earthquake zone is an area of the strongest seismic activity, and is closely related with large-scale earthquakes.

著者

河角 廣

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.15, no.1, pp.6-12, 1943

著者

河角 廣 本間 正作

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.9, no.2, pp.59-68, 1937

著者

河角 廣

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.15, no.8, pp.187-192_1, 1943

著者

河角 廣

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.4, no.3, pp.167-169, 1932

著者

河角 廣

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.6, no.1, pp.32-53, 1934

著者

河角 廣

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.4, no.2, pp.71-94, 1932

著者

河角 廣

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.16, no.2, pp.29-32, 1944

著者

河角 廣 鈴木 武夫

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.4, no.5, pp.277-307, 1932

著者

岸尾 政弘 山川 宜男

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.22, no.3, pp.219-234, 1969-11-30 (Released:2010-03-11)

参考文献数

27

被引用文献数

1 1

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The precision and accuracy of locations of hypocenters of the earthquake off Tokachi of 16 May 1968 and its aftershocks are discussed mainly based on the comparison between both data determined by JMA and USCGS.USCGS epicenters are generally on the continental side of JMA epicenters. The average distance of both JMA and USCGS epicenters of each shock is 26.4km. However there are systematic differences between the JMA-USCGS epicenter deviation of aftershocks north of the mainshock and those of aftershocks south of the mainshock. The USCGS epicenters of northern aftershocks are deviated to north-west direction from the JMA epicenter while USCGS epicenters of southern aftershocks are deviated to west direction from the JMA epicenter.Focal depths of USCGS hypocenters are a little deeper than those of JMA hypocenters. 40% of JMA hypocenters and 80% of USCGS hypocenters are located in the depth of 30-40km which correspond to the top layer of the mantle.Slight differences of b-values in the magnitude-frequency relations are observed among aftershockes in the northern area (around the epicenter of the greatest aftershock), those in the middle area (around the epicenter of the main shock) and those in the southern area (around the epicenter of the second greatest aftershock).The geophysical significance of the above results is briefly discussed.

著者

入山 淳

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.1, pp.14-20, 1968

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The internal structures of Venus, Marss, and the asteroid are examined in the light of the thermal state. The angular velocity of rotation, surface magnetic field strength, and <i>C</i>/<i>Ma</i>² are used as constrained conditions.<br>Results of calculations show that the model terrestrial planets with chondritic composition are consistent with the above constrained conditions, provided that the smaller the size of planets is, the lower the initial temperature is.<br>The internal structure of Venus is similar to that of the earth. From the thermal structure and the slow rotation, the initial temperature within Venus is about 300-400deg. higher than that of the earth.<br>The initial temperature of Mars should be below 600&deg;K, provided that Mars is free of the metallic core.<br>The asteroid must have an iron core, a mantle, and a crust, provided that the initial temperature throughout within the asteroid was above 1, 300&deg;K.

著者

芝崎 文一郎

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.61, pp.415-423, 2009

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Recent high-resolution observations of crustal movements have revealed the occurrence of slow slip events (SSEs) along the deep parts of subduction interfaces. This report reviews the possible models for SSEs using rate- and state-dependent friction laws. SSEs can be modeled under the condition close to the stability transition. The triggered SSEs can be modeled considering a conditionally unstable cell. The self-triggered SSEs can be reproduced in a region that is unstable but close to being stable. In this case, the ranges of the constitutive law parameters for reproducing SSEs are limited. Further, SSEs can also be modeled by considering the frictional property of an unstable-stable transition zone that exhibits velocity weakening at low slip velocity and velocity strengthening at high slip velocity; this model is proposed on the basis of the results obtained in an experiment using halite around an unstable-stable transition zone. By considering this frictional property, Shibazaki and Shimamoto have reproduced short-term SSEs that are similar to the observed SSEs. This friction law needs to be verified experimentally under conditions that are relevant to the fault zones of SSEs. It is theoretically expected that for slip failure processes the propagation velocity is proportional to the slip velocity. This relationship appears to hold for observed SSEs. Therefore, SSEs can be regarded as slip failure processes occurring at deep subduction plate interfaces.

著者

岡野 健之助 木村 昌三

出版者

公益社団法人 日本地震学会

雑誌

地震. 2輯 (ISSN:00371114)

巻号頁・発行日

vol.49, no.3, pp.361-374, 1996-11-23

参考文献数

45

被引用文献数

5 1

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We propose a new idea for the crustal movements associated with past great Nankai earthquakes in Shikoku and the surrounding region, Southwest Japan. This study makes clear that the movements are not due to the oblique subduction of the Philippine sea plate, but due to superposition of strong seismic shaking to the uppermost crust in a compressional stress state in the E-W direction. The ground of this idea is as follows: at the time of the 1707, 1854 and 1946 Nankai earthquakes the Kochi plain subsided and the Muroto and Ashizuri peninsulas uplifted, whereas old documents show that the Kochi plain did not subside at the time of the 1605 Nankai earthquake and therefore no uplifting of the peninsulas is inferred because it is based on a set of subsidence of the Kochi plain and uplifting of the Muroto peninsula appearing at the time of the 1707, 1854 and 1946 Nankai earthquakes. This is explained by the reason why the 1605 (Keicho) earthquake was not accompanied with strong shaking of the ground owing to the tsunami earthquake. Next, because the uplifted peninsulas have anticline axes of the N-S direction, from unconsistency in stress direction it is difficult to attribute the uplifting to the subduction in the NW direction of the Philippine sea plate. On the other hand, it is easily explained that the uplifting was caused by the stress in the EW direction enhanced by strong seismic shaking. Tosa bay, which spreads between the Muroto and Ashizuri peninsulas, is characterized by depression. To be able to explain this depression is not by the elastic rebound theory, but by our idea. The undulation in the forearc zone composed of anticlines (peninsulas) and wide depressions (bays), which range alternately along the Japan island arc, can not also explained by the elastic rebound theory. In addition, we consider that the compressional strain variation in the NW direction of the ground surface observed at present in Shikoku does not result from the oblique subduction in the NW direction of the Philippine sea plate, but it is recovering the overdisplacement of the ground surface caused by the coseismic movement (2-3m at the ground surface) in the SE direction of the Muroto promontory by reverse faulting of the 1946 earthquake. Moreover, this study shows that unconsistency in directions of P axes between the 1946 Nankai earthquake and mantle earthquakes presently occurring in Shikoku and its vicinity is succesfully explained by taking account of constraint of the displacement in the direction along the Japan island arc.

著者

神田 茂

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.2, pp.142-143, 1968