Investigation of the earthquake sequence off Miyagi prefecture with historical seismograms
Investigation of the earthquake sequence off Miyagi prefecture with historical seismograms
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DOI：
10.1186/bf03352657
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发表时间：
2006-01-01
影响因子：
3
通讯作者：
Mori, Jim
中科院分区：
文献类型：
--
作者：
Kanamori, Hiroo;Miyazawa, Masatoshi;Mori, Jim
我们对发生在宫城县近海的1933年（6月18日21:37 UT）、1936年（11月2日20:45 UT）、1937年（7月26日19:56 UT）、1978年（6月12日08:14 UT）和2005年（8月16日02:46 UT）几次地震的旧地震记录进行了研究。地震研究委员会（2003）最近预测“未来30年发生另一场类似地震的概率为99%”的基础是1936年、1978年和其他几个早期事件序列的特征地震模型。为了评估特征地震模型的有效性，我们比较了帕萨迪纳、德贝尔特、阿布山、阿索、韦斯顿、斯特拉斯堡和克赖斯特彻奇记录的这些地震的波形、大小和其他特征。结果表明：(1)1978年地震的地震矩是2005年地震的3 ~ 4.5倍；(2) 1936年奥运会和2005年奥运会的规模大致相同，地点也相当接近；(3) 1937年的地震比1936年的要小，而且深度明显加深，深度可能达到90公里。相比之下，1933年的事件比1936年的事件要浅得多。这些事件之间的差异太大，无法证明使用简单的特征地震模型进行概率预测是合理的。本区及其南部邻近俯冲带的地震滑动率约为板块辐合率的1/4，这对本区的长期地震危险性具有重要意义。
We investigated the old seismograms of several earthquakes which occurred offshore of Miyagi prefecture in 1933 (June 18, 21:37 UT), 1936 (Nov. 2, 20:45 UT), 1937 (July 26, 19:56 UT), 1978 (June 12, 08:14 UT), and 2005 (Aug. 16, 02:46 UT). A characteristic earthquake model for the sequence of the 1936, 1978, and several other earlier events is the basis of the recent forecast by the Earthquake Research Committee (2003) that "The probability of the Occurrence of another similar earthquake in the next 30 years is 99%". To assess the validity of the characteristic earthquake model, we compared the waveforms, size and other characteristics of these earthquakes recorded at Pasadena, DeBilt, Abuyama, Aso, Weston, Strasbourg, and Christchurch. We conclude that (1) The 1978 event is 3 to 4.5 times larger (in seismic moment) than the 2005 event; (2) The 1936 and the 2005 events are about the same size and are fairly close in location; (3) The 1937 event is smaller than the 1936 event, and is significantly deeper, possibly as deep as 90 km. In contrast, the 1933 event is significantly shallower than the 1936 event. The differences between these events are too large to justify the use of a simple characteristic earthquake model for the probabilistic forecast. The seismic slip rate in this area and along the adjacent subduction zone to the south is about 1/4 of the plate convergence rate, which has an important implication for the long-term seismic hazard in this area.