Recurrence behavior of short-term slow slip and correlated nonvolcanic tremor episodes in western Shikoku, southwest Japan
Recurrence behavior of short-term slow slip and correlated nonvolcanic tremor episodes in western Shikoku, southwest Japan
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DOI：
10.1029/2008jb006050
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发表时间：
2010-06-17
影响因子：
3.9
通讯作者：
Obara, Kazushige
中科院分区：
文献类型：
--
作者：
Hirose, Hitoshi;Obara, Kazushige
根据日本国立地球科学与防灾研究所的高网倾斜仪资料，我们确定了2002-2007年日本西南部四国西部地区7次重复的短期慢滑事件(SSE)的随时间变化的震源过程。这些倾斜仪记录了清晰的SSE信号，其特征是上升缓慢，持续时间长达一周，震级在10(-2)-10(-1)微拉德量级。我们对7个SSE的倾斜记录采用了含时滑移反演方法。对于每个SSE，一个滑移区在俯冲板块走向方向上以大约10kmd(-1)的速度移动。将慢滑移区与伴随非火山地震的震中在白天时间分辨率上进行比较，发现这两种现象位于比以往报道的更小的区域内，并作为一组迁移。每个SSE的矩率函数与震颤活动的时间变化有很好的相关性。对所分析的所有SSE的滑移分布进行了比较，结果表明，所有的SSE都有一块直径接近30公里的慢滑带。此外，滑移片的位置与地震和甚低频地震的震中很好地吻合。这些证据表明，已识别的滑移斑块是该地区主要的慢滑斑块之一，SSE的重现可能受该斑块的控制，这些“慢地震”可能是板块深部界面上单一滑动过程的不同表现。
From the National Research Institute for Earth Science and Disaster Prevention Hi-net tiltmeter data, we determine time-dependent source processes of seven repeating short-term slow slip events (SSE) in the western Shikoku region, southwest Japan, over the period from 2002 to 2007. The tiltmeters record clear signals of SSEs characterized by a slow rise, a week-long duration, and a magnitude on the order of 10(-2)-10(-1) mu rad. We apply a time-dependent slip inversion method to the tilt records for the seven SSEs. For each SSE, a slip area migrates in the strike direction of the subducting slab at a rate of similar to 10 km d(-1). Comparing the slow slip area with epicenters of accompanying nonvolcanic tremors in subday time resolution, we find that the two phenomena are located on a smaller area than previously reported and migrate as a group. A moment rate function for each SSE exhibits good correlation with the temporal change in tremor activity. A comparison of the slip distributions of all of the analyzed SSEs shows that there is a patch of slow slip area (similar to 30 km in diameter) that is shared by all of the episodes. In addition, the location of the slip patch is in good agreement with the epicenters of tremors and very low frequency earthquakes. These lines of evidence suggest that the identified slip patch is one of the main slow slip patches in the region and a recurrence of SSEs may be controlled by the patch and that these "slow earthquakes" might be different manifestations of a single slip process on the deep plate interface.