著者

渡辺 邦彦

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.1, pp.32-40, 1970-04-28 (Released:2010-03-11)

参考文献数

6

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On February 21, 1968, a large earthquake occurred at Ebino plateau, south-west part of Miyazaki Pref. in Kyushu. Since then, Ebino earthquake swarm had been active for about one year. Abuyama Seis. Obs., Sakurajima Volcano. Obs. and Disast. Prey. Res. Inst. of Kyoto Univ. made the temporary observation at 5 stations. The main results on the nature of the Ebino earthquake swarm are as follows:1) The epicentral region characteristically changed its shape with time.2) The aspects of the push-pull distribution of the initial P motions appeared to be nearly the same both in large shocks and microearthquakes, showing the same focal mechanism in both cases. This phenomenon does not seem to vary throughout the whole period of this study.3) According to the wave-period analysis, we recognized the interesting relation between the location of the epicenter and the _frequency of those shocks. It may be considered that this was caused by the difference of the properties of the crustal rocks in the hypocentral region from those outside the focal area.

著者

中尾 節郎 片尾 浩 澁谷 拓郎 渡辺 邦彦

出版者

京都大学防災研究所

雑誌

京都大学防災研究所年報 (ISSN:0386412X)

巻号頁・発行日

no.45, pp.561-569, 2001

被引用文献数

1

著者

渡辺 邦彦 岡本 拓夫

出版者

京都大学

雑誌

基盤研究(C)

巻号頁・発行日

1995

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平成7年度〜平成9年度の3年間の研究成果の概要は下記の通りである。研究目的は、自然電位の観測でノイズとされる電車の漏洩電流を信号源と考え、電車軌道から約3kmの北陸観測所で漏洩電流波形を基準とし、それより約15km離れた池田観測室での観測波形を比較し、それによって両観測点間の歪場の変動を電磁気的に解析するものである。特に、地殻ブロック境界の観測点は、広域応力場の状況変化を強く反映すると考えられるので、時間的変動を解析することで、地殻歪の変動を測定することができる。研究成果:1.温見断層に着目し、福井県の北陸観測所坑内と池田観測室で地電位差観測を実施した。2.経年変動を解析した。北陸観測所坑内の自然電位分布は、湿潤度に依存する傾向が見られた。池田観測室では、温見断層に直交する方向と平行な方向に長基線と短基線の電極を配置した。断層に平行方向は地盤の状態により不安定であるが直交方向は安定した年周変動も測定された。地震活動との関連は今後の課題である。3.北陸観測所と池田観測室とで1秒毎サンプリングによる漏洩電流観測を実施した。池田での波形は北陸観測所の数分の1に振幅が減衰するが、波形変形はそれほどなかった。FFTによると、解析限界を超える周波数成分変化は認められなかった。今後、時間的変動と高周波成分までの解析を充実する予定である。4.特定の成分にのみ現れる漏洩電流と思われる特徴的波形を認めた。伝播方向や変電所と電車の位置関係の特定が必要である。特に池田の場合、出現する成分が断層に直交する成分のみであることから、地殻ブロックに関わる可能性が有る。

著者

岸本 兆方 尾池 和夫 渡辺 邦彦 佃 為成 平野 憲雄 中尾 節郎

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.31, no.3, pp.265-274, 1978-10-31 (Released:2010-03-11)

参考文献数

8

被引用文献数

1

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Continuous observation of micro-earthquakes has been done by a network of the Tottori Micro-earthquake Observatory since 1964 and it has been done by a network of the Hokuriku Micro-earthquake Observatory since 1971. These networks were improved by setting up the telemeter observation system and by the development of recording system since 1976.Signals of three components of short period seismic waves observed at 8 satellite stations are transmitted continuously through the telephone lines to the Tottori Observatory. Signals observed at 7 satellite stations are transmitted to the Hokuriku Observatory. Only vertical components of selected three stations are transmitted from the Tottori and the Hokuriku Observatory to the Disaster Prevention Research Institute in Uji and continuously recorded by long term ink-writing recorders.These seismic waves are recorded by three kinds of recording systems at each observatory. Seismic activity is continuosly monitored by newly developed long term ink-writing recorders for vertical components of all stations. Earthquakes observed at more than two of key stations are recorded by data-recorder and pen-recorder with 14 channel recording units started by a triggering signal.Overall frequency range of the telemetering observation system is from 1 to 50Hz and dynamic range is about 40db. Maximum time delay of lines is about 20msec. This time delay is constant for each line and can be corrected for the accurate calculation.

著者

伊藤 潔 渡辺 邦彦

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.30, no.1, pp.43-54, 1977-04-05 (Released:2010-03-11)

参考文献数

10

被引用文献数

1 3

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Focal mechanisms of very shallow earthquakes on the west and the southwest of Lake Biwa have been determined by smoothing the first-motion radiation pattern and by individual solutions. Published focal mechanism solutions are also used to examine the tectonic stress which generates earthquakes in the north Kinki district. Along the west coast and the east coast of Lake Biwa seismic active regions of very shallow earthquakes occur and in Lake Biwa seismic activity is very low. Most of mechanism solutions in these active regions are reverse faultings with the maximum pressure axes in the direction of nearly east-west or southeast-northwest. In other regions of north Kinki district and west Chubu district dominant type of faulting is strike-slip with the same pressure direction. These types of faulting from earthquake focal mechanism solutions agree well with those of tectonic active faults developed in this area. The reverse faulting as well as the high seismicity on the both coasts of Lake Biwa is consistent with the subsedence of Lake Biwa which has been continued throuth the Quaternary.