In the time from June to July 1968 there occurred a swarm of relatively small earthquakes in the Galapagos Island of the Eastern Pacific region. The total number of the events, as reported in the Earthquake Data Report of the U.S. Coast and Geodetic Survey was 260. The Galapagos Islands are one of the volcanically most active regions in the world. For example, there are found: Volcano La Cumbre in Fernandina Island and Volcano Wolf, Volcano Darwin and Volcano Alcedo in Isabela Island in Galapagos Islands. An eruption phenomenon was reported just before the present earthquake activity at Fernandina Island, by the Center for Short Lived Phenomena of the Smithsonian Institution. The activity continued from 15hOOm to 23hOOm (U.T.) on May 21, on a small-scale. But there was an intensive eruption at 10h18m on June 18. The main visible result of the activity was the collapse of the caldera floor, the southeast part of which dropped 300m. The volume of collapse was 1～2km3. The activity area of the earthquakes swarm includes the region of Fernandina Island and Isabela Island. The total number of the larger earthquakes of the swarm with magnitude 5.0 or more, which occurred through the whole period, amounted to 16. We report the results of an investigation, using the data published by the USCGS as well as the seismograms of long-period type obtained at the Galapagos Seismological Station of WWSSS, and discuss in this paper.
雑誌名
東京大學地震研究所彙報 = Bulletin of the Earthquake Research Institute, University of Tokyo
巻
48
号
5
ページ
935 - 953
発行年
1970-12-05
ISSN
00408972
書誌レコードID
AN00162258
フォーマット
application/pdf
日本十進分類法
453
出版者
東京大学地震研究所
出版者別名
Earthquake Research Institute, University of Tokyo
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49. 1968年6月のGalapagos諸島の群発地震について
ji0485014.pdf
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