Spatiotemporal slip distributions of three long-term slow slip events beneath the Bungo Channel, southwest Japan, inferred from inversion analyses of GPS data
Spatiotemporal slip distributions of three long-term slow slip events beneath the Bungo Channel, southwest Japan, inferred from inversion analyses of GPS data
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DOI：
10.1093/gji/ggv022
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发表时间：
2015-06-01
影响因子：
2.8
通讯作者：
Ide, Satoshi
中科院分区：
文献类型：
--
作者：
Yoshioka, Shoichi;Matsuoka, Yoshiko;Ide, Satoshi
我们估计了 1997 年至 1998 年、2002 年和 2004 年以及 2009 年和 2011 年期间发生在丰后海峡下方俯冲菲律宾海板块与日本西南部阿穆里亚大陆板块之间的汇聚板块边界处的三个长期慢滑移事件 (L-SSE) 的时空滑移分布。为此，我们采用了使用贝叶斯信息准则的反演方法（ABIC），包括以下三个先验约束：空间滑移分布具有一定的平滑性、滑移方向大多指向板块汇聚方向、滑移的时间变化具有一定的平滑性。我们的结果表明，三个 L-SSE 有一个共同特征：滑移区域以加速滑移速度向西南扩展。我们还发现主要滑动区域向西南迁移了大约50-100公里年(-1)。相比之下，滑移区域向西南和东北的迁移，其方向因事件而异，在滑移速度达到最大的时期之前或之后也被识别出来。将获得的三个L-SSE的时空滑差分布与我们前期研究中获得的滑差赤字率分布进行比较，研究了滑差赤字率分布引起的滑差赤字的积累过程以及由三个L-SSE的时空滑差分布引起的滑差赤字的释放过程。在丰后水道西板块界面，由于滑移赤字率较小，而与三个L-SSE相关的滑移量较大，估计大部分累积的滑移赤字已被释放。相反，在东部板块界面，由于滑移赤字率较大，且与三个L-SSE相关的滑移量较小，因此估计滑移赤字已有效积累。这些结果表明，三个 L-SSE 的滑移区域和强耦合区域在空间上并不互补；即使在沿弧线大致相同的深度范围内，累积的滑移不足也显示出空间变化。
We estimated spatiotemporal slip distributions from three long-term slow slip events (L-SSEs) that occurred beneath the Bungo Channel at the convergent plate boundary between the subducting oceanic Philippine Sea plate and the continental Amurian plate in southwest Japan between 1997 and 1998, 2002 and 2004 and 2009 and 2011. For this purpose, we employed an inversion method using a Bayesian Information Criterion (ABIC), which included the following three prior constraints: the spatial slip distribution was smooth to some extent, slip directions were mostly oriented in the direction of plate convergence and the temporal change in slip was smooth to some extent. Our results revealed that the three L-SSEs had a common feature: slipped regions expanded southwestward at accelerating slip velocities. We also found that major slipped regions migrated southwestward by approximately 50-100 km yr(-1). In contrast, southwestward and northeastward migration of the slipped regions, whose direction differed from event to event, was also identified before or after the periods when the slip velocities were at their greatest. Comparing the obtained spatiotemporal slip distributions of the three L-SSEs with slip-deficit rate distributions obtained in our previous study, we investigated the accumulation process of the slip deficit caused by slip-deficit rate distributions and the release processes of the slip deficit caused by the obtained spatiotemporal slip distributions of the three L-SSEs. At the western plate interface of the Bungo Channel, as the slip-deficit rate was small and the amounts of slips associated with the three L-SSEs were large, most of the accumulated slip deficit was estimated to have been released. In contrast, at the eastern plate interface, as the slip-deficit rate was large and the amounts of slips associated with the three L-SSEs were small, the slip deficit was estimated to have accumulated effectively. These results suggest that the slipped regions of the three L-SSEs and the strongly coupled region are not spatially complementary; the accumulated slip deficit showed spatial variation even at approximately the same depth range along the arc.