著者

堀内 茂木 松澤 暢 長谷川 昭

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.52, no.2, pp.241-254, 1999-10-20 (Released:2010-03-11)

参考文献数

22

被引用文献数

2

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Many earthquakes occur after a destructive shallow earthquake or before a volcanic eruption. It is very important to determine accurate hypocenters as early as possible at a time of such a huge seismic activity, since seismicity data are essential for the understanding of the crustal activity. We developed an automatic data processing system of seismic waves which has a swarm mode processing and can locate accurate hypocenters even for a huge seismicity. The main difference between the swarm and ordinary modes is that the former assumes hypocenters for all events to be in a small area. Event detection is made by estimating approximate origin times calculated from each picked arrival time of P and S waves for several low noise stations close to the swarm area and each theoretical travel time from the swarm area to these stations. We assume events having similar origin times to be seismic events. The system picks P and S wave arrival times not only for these stations but also for all stations by setting time windows at their arrivals which are calculated from the approximate origin time. The application of swarm mode to waveform data at a huge seismicity after the 1996 Onikobe earthquake sequence showed that the new system is very effective and can determine more precise hypocenters rather than manual pickings.

著者

伊藤 喜宏 岡田 知己 松澤 暢 海野 徳仁 長谷川 昭 前田 憲二

雑誌

日本地震学会講演予稿集 = Programme and abstracts, the Seismological Society of Japan

巻号頁・発行日

vol.1999, no.2, 1999-11-09

著者

内田 直希 松澤 暢 三浦 哲 平原 聡 長谷川 昭

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.59, no.4, pp.287-295, 2007-03-25 (Released:2013-08-05)

参考文献数

26

被引用文献数

4

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Spatio-temporal distribution of quasi-static slip on the plate boundary east off Miyagi and Fukushima prefectures, NE Honshu, Japan is estimated by using small repeating earthquake data. The analysis of small repeating earthquakes has advantages of relatively high spatial resolution, especially near the trench, and the availability of long-term data (22 years) compared to GPS data. The results show that the repeating earthquakes are distributed outside the coseismic slip areas (asperities) of large earthquakes, showing that fault creep is dominant outside the asperities. The cumulative slip (slip histories) of small repeating earthquake groups reveal the existence of many non-steady aseismic slip events. Most of the episodic quasi-static slip events are associated with M≥ 6 earthquakes and they are frequently seen in the areas near the Japan trench in particular. Minor afterslip (∼15cm) of the 2005 Miyagi-oki earthquake (M7.2) is also estimated in the area which encompasses the coseismic slip area of the 2005 earthquake.

出版者

労働経済社

巻号頁・発行日

0000

著者

稲田 弘子

出版者

聖徳大学

雑誌

研究紀要. 短期大学部 (ISSN:09166661)

巻号頁・発行日

vol.32, pp.165-170, 1999-12-08

著者

溝上 恵

出版者

日本測地学会

雑誌

測地学会誌 (ISSN:00380830)

巻号頁・発行日

vol.8, no.1, pp.29-37, 1962-12-30 (Released:2010-09-07)

参考文献数

5

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It is the well known fact that notable relations exist between the distribution of Bouguer gravity anomalies and the structural units of the surface geology in Hokkaido, which have been formed by the orogenic movements since the Miocene period. For example, the Hidaka mountains which have been violently upheaved in the most recent geologic age, are areas of remarkably high gravity while the Tempoku-Urakawa Zone which have rapidly subsided in the same age is the area of strong negative anomalies running parallel to the mountains. In this paper, it is shown that the pattern of the strong negative anomalies of the Tempoku-Urakawa Zone can be explained by Vening Meinesz's theory of visco-elastic deformation of the crust by compressive stress. Time required for the deformation of the crust and density of sedimentary layer was also calculated and these results are in good harmony with the geohistorical evidence in this region.

著者

勝俣 啓 卜部 卓 森谷 正義 中村 正夫 瀬戸 憲彦 中村 功 溝上 恵

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.4, pp.499-511, 1990-12-24 (Released:2010-03-11)

参考文献数

4

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Explosion seismic refraction experiments were carried out in 1988 for the investigation of the shallow crustal structure in the volcanic island of Nii-jima, northern part of Izu-Bonin island arc, Japan. One hundred and eight seismograms were obtained at 54 temporary stations aligned on the three profiles arranged like a triangle on the island. The main features of the shallow crustal velocity structure revealed by the travel time analysis are as follows:1) Surfaces of high velocity layers are raised beneath volcanos in the island of Nii-jima.2) The structure mostly consists of three layers with P-wave velocities of 1.9km/s, 2.8km/s and 4.5km/s, respectively.3) A layer with a velocity of 1.5km/s exists over the 1.9km/s layer at two explosion sites in shore.4) There is no 1.9km/s layer beneath Mt. Acchi volcano in the northern part of the island.5) The top of the 2.8km/s layer is much shallower beneath Mt. Mineji volcano in the central part of the island and beneath Ajiaiso beach in the northwestern part of the island.6) Both top of the 2.8km/s layer and that of the 4.5km/s layer are much shallower beneath Mt. Acchi volcano in the northern part of the island.7) The 1.9km/s layer is thicker beneath the small plain in the central part of the inland, beneath the place between Mt. Mineji and Ajiaiso beach, and beneath Wakago village in the northern part of the island.

著者

溝上 恵

出版者

都政研究社

雑誌

都政研究

巻号頁・発行日

vol.39, no.7, pp.4-9, 2006-07

著者

溝上 恵

出版者

地震予知総合研究振興会

雑誌

地震ジャ-ナル (ISSN:09125779)

巻号頁・発行日

no.40, pp.29-36, 2005-12

著者

溝上 恵

出版者

国土計画協会

雑誌

人と国土21 (ISSN:13469576)

巻号頁・発行日

vol.30, no.4, pp.8-15, 2004-11

著者

溝上 恵

出版者

日本地質学会

雑誌

地質学論集 (ISSN:03858545)

巻号頁・発行日

no.35, pp.1-10, 1990-12-01

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The East Off Chiba Prefecture Earth quake (M6.7) on December 17, 1987 was located at 35°22'N, 140゜30'E, about 10 km off the east coast of Chiba Prefecture with focal depth of 58 km. The intensity of ground motions V on JMA scale was recorded at Chiba, Chosi and Katsuura, Chiba Prefecture, Central Japan. The earthquake, indentified as an interplate earthquake of the Philippine Sea plate, was accompanied by the after shock activity which propagated at from the depth of 55 km near the lower surface of the plate to the depth of 25 km near the upper surface of the plate. The right-lateral strike slip fault of the earthquake cut across the northeastern edge of the Philippine Sea plate in the NNW-SSE direction. The Eastern Part of Tokyo Earthquake on March 18, 1988 (M6.5) occurred on the plate boundary between the Philippine Sea plate and the Pacific plate. The coincidental occurrence of the two major earthquakes in the southern part of the Kanto district was interpreted as caused by a mechanical coupling between the two plates beneath the district. The 1987 East Off Chiba Prefecture Earth quake was preceded by the long continued earthquakes warms off the coast of Kujyukuri, Chiba Prefecture since 1971 as a possible precursory activity accosiated with a stress concentration at the fault area of the earthquake.

著者

溝上 恵

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.73, no.4, pp.224-242, 1964-08-30 (Released:2009-11-12)

参考文献数

5

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As the present crustal structures have been formed by the tectonic movements through the long geological age, problems of the crustal movements must be studied in connection with the information of the present crustal structures obtained from geological, geomorphological and geophysical methods. In this paper, the relation between the crustal structures and the crustal movements in Japanese islands found by geodetic methods is investigated from the following three points.1) The relation between the changes of the intensity of crustal movements with time and those in space.2) The relation between the horizontal variations of the crustal movements and crustal structures.3) The difference of the characteristics of the crustal movements in orogenic regions (Japanese islands) and in continental platform.

著者

飯高 隆 中村 功 溝上 恵

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.64, no.1, pp.37-50, 1989-06-30

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関東地方においては,これまでに地震波速度構造の不均質性について様々な研究がなされてきた.これらの研究の結果,太平洋プレート,フィリピン海プレートの沈み込みが示された.このように複雑な構造をした地域において,沈み込むプレートの形状を求めることは,大変重要なことである.東京大学地震研究所の日立(HIT)の観測点の地震波記録で,P波とS波の間に立ち上がりのはっきりした後続波が見られた.この研究では,この後続波が,沈み込む太平洋プレート上面でPS変換された波であることを明らかにし,この変換波を用いて沈み込む太平洋プレート上面の深さを求めた.このように変換波を用いる方法は,プレート上面の深さを求めるのに有効であることが知られている.この研究において,関東地方下で求められた太平洋プレート上面は,日立の観測点下で約60kmの深さに求まり,その面は2重深発面の上面にほぼ一致した.また,この深さはS波の反射から求められた結果(小原,1987)と矛盾しない.

著者

溝上 恵

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.55, no.2, pp.483-504, 1980-11-15

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It has been pointed out from geological and geomorphological evidences that the time rate of undulatory crustal movement shows a remarkable dependence on its wavelength. Specific studies on the problem were made by MATSUDA (1960, 1961, 1964), KAIZUKA (1967, 1968) and OTA (1968, 1969). KAIZUKA compared the rate of folding in the Quaternary with the mode of undulatory crustal movements in the present. He indicated such regularities of folding as the smaller the wavelength, the greater the rate of folding and the rate of present folding is in the same order with that of the Quaternary folding.

著者

溝上 恵

出版者

東京大学地震研究所

雑誌

地震研究所研究速報

巻号頁・発行日

vol.12, pp.41-56, 1974-03

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It should be emphasized that when using an array to determine directly dT/dΔ for the study of the structure of the Earth's deep interior, the necessity for the correction for the near surface structures is inevitable, particularly in such a region as the Kii Peninsula where existence of a dipping Moho-discontinuity is expected. A teleseismic slowness vector analysis method given by Zengeni(1970) is applied for the study of the diwing Moho-discontinuity in the Kii Peninsula.

著者

雑賀 敦 平松 良浩 大井田 徹 山岡 耕春

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.75-86, 2001-07-25

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Spatial and temporal variations in seismic anisotropy in the crust are investigated using earthquakes in the crust and at the upper boundary of the subducting Philippine Sea plate in the Tokai region, central Japan. We use waveform data from December 1986 to August 1999 recorded by the micro-earthquake observation network of the Research Center for Seismology and Volcanology, Nagoya University. The method of Silver and Chan (1991) is applied to evaluate splitting parameters, a leading shear-wave polarized direction and a delay between two polarized waves. A total of 362 high-quality waveform data within the incident angle of 35° are analyzed in this study. The leading shear-wave polarized directions are approximately E-W, in spite of differences of focal depths. This direction is consistent with the direction of regional horizontal maximum compressive stress in the Tokai region reported before. The time delay increases in proportion to the focal depth. These results indicate that the regional compressive stress controls anisotropy not only in the upper crust but also in the lower crust. Assuming the uniform distribution of anisotropy, the degree of anisotropy is estimated to be 0.5% in the lower crust. An increase in time delays between two-polarized waves is found before and after the Aichi-ken Tobu earthquake (M = 5.7) in 1997 at the station STN. This variation is statistically significant with the confidence level of 99.999% and is not an apparent change due to a variation in hypocenter distribution. No temporal variation of splitting parameters is found at the station INU. These results can be explained by a change of the volumetric and areal strain in the most-upper part of the crust due to the postseismic slip of the Aichi-ken Tobu earthquake.

著者

山岡 耕春 Yamaoka Koshun

巻号頁・発行日

1986-03-25 (Released:2009-12-22)

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名古屋大学博士学位論文 学位の種類 : 理学博士(課程) 学位授与年月日 : 昭和61年3月25日

著者

山岡 耕春

出版者

国土計画協会

雑誌

人と国土21 (ISSN:13469576)

巻号頁・発行日

vol.39, no.3, pp.16-20, 2013-09

著者

山岡 耕春

出版者

日本航空宇宙学会

雑誌

宇宙科学技術連合講演会講演集 (ISSN:18841945)

巻号頁・発行日

vol.57, 2013-10-09

著者

山岡 耕春

出版者

公益社団法人 精密工学会

雑誌

精密工学会誌 (ISSN:09120289)

巻号頁・発行日

vol.71, no.11, pp.1325-1329, 2005-11-05 (Released:2009-04-10)

参考文献数

3