著者

上嶋 誠

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, no.Supplement, pp.225-238, 2009-07-31 (Released:2013-11-21)

参考文献数

134

被引用文献数

2 3

---

Owing to significant developments in instrumentations, data processing methods and modeling schemes, prospecting electrical conductivity structure with the aid of the magnetotelluric method has become one of the standard geophysical techniques for elucidating dynamics of subsurface crustal activities such as earthquake occurrence and volcanic eruptions. In this paper, after brief introduction of the magnetotelluric method, recent 10-yaer progress of the method and its experiments in crustal active areas in Japan were reviewed. Since electrical conductivity is especially sensitive to the existence of the interstitial fluids and their connectivity, together with existence of high temperature areas, the survey results deepened our understandings for generation mechanisms of earthquakes, seismic faults, localized strain accumulations and volcanic eruptions.

著者

安芸 敬一

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.57, no.3, pp.317-319, 2005-02-20 (Released:2010-03-11)

参考文献数

21

被引用文献数

1

---

Looking back at the last 100 years of seismology, we are most impressed by the great contrast between the complexity of the first observed seismograms and the simplicity of the first theoretical seismogram calculated by Lamb. This complexity of the observed seismogram has made seismology a vital branch of earth sciences. If Lamb was able to explain the observed seismogram then, we would not be celebrating the centennial of Lamb's problem.

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.46, no.4, pp.461-477, 1994-03-14 (Released:2010-03-11)

参考文献数

63

被引用文献数

1

---

Tectonics of the Taiwan region is reviewed. Relative plate motions so far obtained are described and rated. The most reliable solution gives 7.4cm/yr Philippine Sea-Eurasian motion in the N50°W direction in central Taiwan. Plate boundary geometries and modes of plate consumption in the region are discussed on the basis of geophysical, geological and geomorphological data. The major thrust zones at the Western Foothills and the Longitudinal Valley constitute mechanical plate boundaries, but a considerable fraction of the relative plate motion is also consumed by the strike-slip faulting off the southeast coast of Taiwan.The cause for the occurrence of the strike-slip faulting off the southeast coast of Taiwan is discussed based on the various models so far proposed. The bending of the Philippine Sea plate due to the subduction at the Ryukyu Trench and the collision in the Longitudinal Valley are similar to the tectonics of the Izu Peninsula region in Japan, and are the most likely cause for the strike-slip faulting.The reconstruction of the motion and plate boundaries in the vicinity of Taiwan for the past 4-6m. y. is reviewed. The Philippine Sea-Eurasian motion for the past 4 Ma is similar to the present one. The motion prior to 4 Ma may be more northward than present due to the absence of subduction at the Philippine Trench. The Luzon arc started to collide with the continental margin of S. E. China around 4 Ma.

著者

井田 喜明 山口 勝 増谷 文雄

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.39, no.1, pp.111-121, 1986-03-25 (Released:2010-11-17)

参考文献数

6

被引用文献数

1

---

Seismic data obtained in Kirishima Volcano Observatory thruogh June, 1982 to August, 1985 were analyzed to reveal the nature of recent earthquakes in Kirishima volcano. In this period, signifucant earhquakes swarms were observed repeatedly in three regions around Shinmoe cone, Ohgiri hot-spring area and Ohnami-ike crator lake. Seismicities in these Fault plane solutions show that a north-west to south-east extensional stress is dominant in Ohgiri and Shinmoe, while Ohnami-ike regions has earthquakes that represent a strike a slip fault motion along a line extending north-west to south-east. These events in Ohnami-ike are explained as a displacement across the fault to adjust the extentional deformation in Ohgiri and Shinmoe.

著者

今村 明恒

出版者

公益社団法人 日本地震学会

雑誌

地震 第1輯 (ISSN:00371114)

巻号頁・発行日

vol.13, no.3, pp.82-86, 1941-03-25 (Released:2010-11-17)

著者

鷺谷 威 西村 卓也 畑中 雄樹 福山 英一 L. ELLSWORTH

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.54, no.4, pp.523-534, 2002-04-25 (Released:2010-03-09)

参考文献数

21

被引用文献数

2 12

---

The 2000 Western Tottori Earthquake occurred on October 6, 2000, in the border of Tottori-Shimane prefectures. Japanese nationwide continuous GPS array recorded coseismic as well as postseismic crustal movements due to the earthquake. The maximum coseismic displacement observed was about 17cm. The coseismic deformation pattern clearly demonstrates a left-lateral strike slip source mechanism, which is consistent with seismic data analysis results. Leveling surveys around the focal region revealed up to 15cm vertical displacement near the source fault. GPS sites northeast of the source region were displaced up to 2cm to the northeast during 3 months after the earthquake, while a GPS site on the other side moved to the south by 2cm. Crustal deformation data are inverted to estimate two types of static fault models. One is a single rectangular fault model which can reproduce the coseismic displacement vectors observed by GPS. The other fault model, whose geometry is derived from precise re-determination of aftershocks, provides detailed information on slip distribution. We need to supplement subfaults in the shallower (depth<4km) parts to the original fault model in order to explain leveling change data, which implies systematic bias in the hypocenter depth or a full relaxation of stress by the main shock. Estimated moment magnitude were 6.6 and 6.7 for the two models, consistent with waveform inversion analysis.

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

田村 理納 宮澤 理稔

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.69, pp.99-111, 2017-03-10 (Released:2017-05-16)

参考文献数

45

---

We investigated the triggering process for the Mj6.4 Eastern Shizuoka earthquake of 15 March 2011, which occurred 4 days after the 2011 Mw9.0 Tohoku-Oki earthquake and about 4 minutes after the Mj6.2 Fukushima-Oki earthquake. The static Coulomb failure stress change on the fault of the Eastern Shizuoka earthquake from the Tohoku-Oki earthquake, was about 20 kPa, and the largest dynamic stress change by the passing surface waves was about 200 kPa. The largest dynamic stress change from the Fukushima-Oki earthquake and the largest tidal stress change after the Tohoku-Oki and before the Eastern Shizuoka earthquake were about 0.3 kPa and 1.4 kPa, respectively, while those at the onset of the Eastern Shizuoka earthquake were at most 0.01 kPa and −0.5 kPa, respectively. We also analyzed seismicity by detecting earthquakes immediately preceding the Eastern Shizuoka earthquake, which is done using a matched filter technique. A single M1.0 event that occurred about 17 hours before the Eastern Shizuoka earthquake and located about 3 km NNE from the hypocenter was found, however, this event may not be classified as a foreshock if we consider the background seismicity in this region before 2011. We propose that the seismic cycle was possibly advanced by about 101 to 102 years and delayed triggering might have occurred for the Eastern Shizuoka earthquake. The eventual earthquake was ready to occur to some extent, when the Tohoku-Oki earthquake occurred. The fault strength had significantly decreased due to imposed large dynamic and static stress changes from the Tohoku-Oki earthquake and probably its large aftershocks, in terms of a rate and state dependent friction law.

著者

川崎 一朗 加藤 照之

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.69, pp.11-22, 2016-07-10 (Released:2016-11-10)

参考文献数

40

---

The way to have another look at earthquake prediction/forecast researches in Japan is discussed from a border between the seismology and the history and philosophy of science. Scientific revolution is often symbolically expressed as the shift of the paradigm, idea of which was introduced by Thomas Kuhn. In the field of earthquake prediction research, here we tentatively define its paradigm as a combination of the following ideas - though these would be too humble :1) plate tectonics, 2) asperity or distribution of frictional strength on a fault surface, 3) constitutive law of friction, 4) numerical simulations of precursory process, and 5) observation system of crustal deformation prior to a large earthquake. The case for the paradigm is that any of convincing precursors to a large earthquake has not been observed yet, and, the distribution of frictional strength on a fault surface, in particular, on the subducting plate boundary, is not precisely estimated. Our history of modern seismology is too short to resolve such observational problems. Given that essence of the progress in science is the repetition of proposal of hypotheses and its verification or its rejection, scientists are strongly obliged to propose new hypotheses based on new findings and discoveries to be tested and discussed. Even if the result does not occur along prediction/forecast, it should be appreciated as the science if their scientific context is acceptable. Progressive theory that prevails over degressive one, in the meaning of “research program” theorem proposed by Lakatos Imre, will stimulate the earthquake prediction research in Japan, for which the authors truly believe in. Individual researchers working on the prediction/forecast researches are responsible only for their scientific context. Administrative organizations of seismologists such as the Headquarters for Earthquake Research Promotion and the Coordinating Committee for Earthquake Prediction should take a responsibility for our society.

著者

加藤 護

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.76, pp.71-75, 2023-07-06 (Released:2023-09-27)

参考文献数

16

著者

加藤 護

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.68, no.6, pp.163-167, 2016-03-10 (Released:2016-05-19)

参考文献数

21

被引用文献数

2 2

著者

寒川 旭

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.39, no.1, pp.15-24, 1986-03-25 (Released:2010-11-17)

参考文献数

36

被引用文献数

3 2

---

The Kandayama tumulus is located in the eastern part of the Osaka okain. Crossing this tumulus is the N-S trending Konda fault, which has displaced river terraces and middle Pleistocene deposits. Just on the fault, the bank of the tumulus was upthrown eastward, and the north-western corner of the burial mound arumbled in.These facts show that the latest displacement of the fault occured after the construction of the tumulus. The Kondayama tumulus is presumed to be the tomb of the Emperor Ohjin and constructed in the 4th or 5th centry. The earthquake of 1510 is the only big earthquake recorded in this region, which destroyed the neighbouring Fujiidera temple. The displacement of the tumulus is presumed to have been caused by this earthquake.The magnitude of the earthquake is estimated M7. 1 judguing from the maximum displacement (1. 8m) of the bank of the tumulus. The mean rate of the Konada fault is calcurated 0. 25-0. 4m/103 and the recurrence interval of the earthquake is assumed 5000-7500y.

著者

今村 明恒

出版者

公益社団法人 日本地震学会

雑誌

地震 第1輯 (ISSN:00371114)

巻号頁・発行日

vol.1, no.1, pp.4-16, 1929-01-15 (Released:2010-11-17)

被引用文献数

1

著者

千釜 章 多田 省一郎 青沼 正光

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.51, no.1, pp.61-73, 1998-07-03 (Released:2010-03-11)

参考文献数

37

被引用文献数

2 2

---

Some specific legends and traces related with historical tsunamis have been handed down among the people in the northern part of Honshu, Japan. Examples are the forest of Hiba buried by a large amount of sand and the resettlement of villages damaged by tsunamis in Shimokita Peninsula, the northeast Honshu. The aim of this paper is to reexamine their reliability by compiling old documents and results from numerical simulation of tsunamis. Results from old documents combined with numerical simulation suggest that the legends at the age of Tensho and Kan-ei period would be associated with not tsunamis but floods. And the story of damage at Tanabu town by the 1611 Keicho tsunami causing resettlement to a higher place is not reliable because the simulated tsunami could not reach the locations of the village. The sequence of events of sand transport to bury Hiba forest at four different ages could be found by filed investigation and result of dating of 14C. The ages do not correspond to the tsunami events. Such process can be explained by a formation of sand dune, meaning that a large amount of sand movement should not be caused by tsunamis.

著者

小林 励司

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.73, pp.225-249, 2021-01-29 (Released:2021-03-30)

参考文献数

38

---

A large earthquake (M7.1) occurred during the 1914 eruption of Sakurajima volcano in Kagoshima prefecture, Japan. I estimated seismic intensities in the present Japan Meteorological Agency (JMA) scale for the 1914 Sakurajima earthquake in Kagoshima city. Previous studies on seismic intensities in Kagoshima city are used their own unique methods to estimated seismic intensities from data of damaged houses and stonewalls. I used a method of estimating seismic intensities from data of damaged houses, which has been commonly used. Previous studies using this method have assumed that each household owns one house, but the numbers of damaged houses in some towns are significantly larger than those of households in the case of the 1914 Sakurajima earthquake. I, therefore, made two assumptions A and B. The assumption A is that each household owns one house. The assumption B is that the ratio of houses to households in each town equal to the maximum ratio of total damaged houses to households. As a result, the maximum seismic intensities for the assumptions A and B are 6 upper and 6 lower, respectively. The areas with higher seismic intensity than 6 lower are consistent with the previous studies on the 1914 Sakurajima earthquake, but the areas with lower seismic intensities than 5 upper are inconsistent because I did not take stonewall damages into consideration, which the previous studies did. I compared our results with distributions of seismic intensities predicted by an attenuation relation between intensity and distance with two different sets of source parameters. One set of source parameters showed seismic intensities of 6 lower and 6 upper in Kagoshima city, and the other set showed those of 5 lower and 5 upper. The observed seismic intensities are on average lower than the predicted ones, probably suggesting that large coseismic slip area is distributed further than epicenter, that Kagoshima city is located in the opposite direction of the rupture propagation and its directivity effect make the amplitudes smaller, or that amplitudes at frequencies which affect seismic intensities are smaller than those expected from the magnitude. The observed seismic intensity distributions are also rougher than the predicted ones and could be affected by local soil conditions.

著者

松本 拓己 伊藤 喜宏 松林 弘智

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.58, no.4, pp.427-443, 2006-03-31 (Released:2010-03-11)

参考文献数

17

被引用文献数

1 1

---

The 2004 Mid Niigata Prefecture earthquake (MJ6.8) that occurred on October 23, 2004 is the 2nd largest intra-plate earthquake after F-net, the broadband seismograph network of the National Research Institute for Earth Science and Disaster Prevention (NIED) was established with a dense and homogeneous distribution all over Japan. We determined moment tensor solutions of the main shock, aftershocks, and earthquakes occurred around mid Niigata prefecture from January 1997 to October 22, 2004, using a surface wave with an extended method of the NIED F-net routine processing. The horizontal distance to the station is rounded to the nearest interval of 1km, and the variance reduction approach is applied to a focal depth from 2km with an interval of 1km. We obtain the moment tensors of 117 events with MJ exceeding 2.8 and spatial distribution of these moment tensors. The focal mechanism of main shock, aftershocks, earthquakes before main shock, is mainly of the reverse fault type with P axes trending WNW-ESE. But the focal mechanism of 15 percent aftershocks is the strike-slip type. There are high dip angle reverse faults, in deep part, and low dip angle reverse faults in shallow part.

著者

山中 浩明 瀬尾 和大 佐間野 隆憲

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.44, no.1, pp.9-20, 1991-03-24 (Released:2010-03-11)

参考文献数

15

被引用文献数

1

---

The seismic refraction survey was conducted in the southwestern part of the Tokyo Metropolitan area to make clear the deep sedimentary structure. Two explosions were made at Daikoku and Maioka in Yokohama city in 1988, and the resultant seismic waves were observed at 83 temporary observation sites along four surveying lines:a) Yumenoshima to Enoshima, b) Daikoku to Nagatsuta, c) Nagatsuta to Kanazawa, andd) around Takatsu.The travel time analysis for the above data and additional data from previous explosions in the area for reference has been made.The followings were our conclusions:1) The subsurface structure consists of five layers characterized by P-wave velocities of 1.8, 2.3, 2.9, 4.7 and 5.5km/s. The top layer with a P-wave velocity of 1.8km/s disappears around Enoshima. The layer with a P-wave velocity of 5.5km/s could not be confirmed for the southwestward area.2) The topography of the layer with a P-wave velocity of 4.7km/s forms a synclined structure having its maximum depth of more than 4km between the Maioka and Daikoku explosion sites. The depth to this layer becomes drastically shallower toward Enoshima.3) The step-like topography of the layer with a P-wave velocity of 5.5km/s, which has been found in the previous study, could not be confirmed, because of low S/N ratios of the observed seismograms.

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1輯 (ISSN:00371114)

巻号頁・発行日

vol.15, no.1, pp.6-12, 1943-01-18 (Released:2010-11-17)

被引用文献数

7

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

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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.

著者

松村 正三

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.49, no.1, pp.85-88, 1996-05-24 (Released:2010-03-11)

参考文献数

15

被引用文献数

1