Seismic and geodetic constraints on Cascadia slow slip
Seismic and geodetic constraints on Cascadia slow slip
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卡斯卡迪亚慢滑移的地震和大地测量约束
DOI：
10.1029/2008jb006090
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发表时间：
2008
影响因子：
--
通讯作者：
T. Melbourne
中科院分区：
文献类型：
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作者：
A. Wech;K. Creager;T. Melbourne
[1]自动检测和定位的震颤震中从幕式震颤和滑动（ETS）在北方卡斯卡迪亚事件提供了一个高分辨率的地图华盛顿的缓慢滑动区。从2004年到2008年的过去四次ETS事件中的数千个震中提供了详细的地图视图约束，这些约束与同步缓慢滑动的大地测量估计相关。这些ETS事件中的每一个都表现出显着的相似性，在时间和地理分布的震颤密度和测地推断的滑动。对最近15个月的ETS间期的分析也揭示了老年性震颤活动在持续时间和程度上与ETS震颤相似。来自ETS和ETS间地震的震中位于30和45公里板块界面深度等值线之间，位于俯冲胡安·德富卡板块锁定部分先前估计以东约75公里处。ETS间震颤重叠，但通常是ETS震颤的下倾，与大地测量观测到的滑动无关，但这可能是因为滑动低于当前GPS检测水平。基于地震和滑动的相关性和地震持续时间和滑动幅度的关系，我们认为，以及解决，尖锐的上倾边缘的地震震中反映了板块界面耦合特性的变化。该边界的区域上倾可能会积累应力，在大逆冲断层地震期间可能发生同震剪切破坏。或者，板块收敛在这一地区可以容纳连续缓慢滑动没有检测到的震颤或缓慢滑动事件有足够长的复发间隔，没有检测到在过去10年的GPS观测。
[1] Automatically detected and located tremor epicenters from episodic tremor and slip (ETS) episodes in northern Cascadia provide a high-resolution map of Washington's slow slip region. Thousands of epicenters from the past four ETS events from 2004 to 2008 provide detailed map-view constraints that correlate with geodetic estimates of the simultaneous slow slip. Each of these ETS events exhibits remarkable similarity in the timing and geographic distribution of tremor density and geodetically inferred slip. Analysis of the latest 15-month inter-ETS period also reveals ageodetic tremor activity similar both in duration and extent to ETS tremor. Epicenters from both ETS and inter-ETS tremor are bounded between the 30- and 45-km plate interface depth contours and locate approximately 75 km east of previous estimates of the locked portion of the subducting Juan de Fuca plate. Inter-ETS tremor overlaps but is generally downdip of ETS tremor and does not yet correlate with geodetically observed slip, but this is likely because the slip is below current GPS detection levels. Based on the tremor and slip correlation and the tremor-duration and slip magnitude relationship, we suggest that the well-resolved, sharp updip edge of tremor epicenters reflects a change in plate interface coupling properties. The region updip of this boundary may accumulate stress with the potential for coseismic shear failure during a megathrust earthquake. Alternatively, plate convergence in this region could be accommodated by continuous slow slip with no detectable tremor or by slow slip events with sufficiently long recurrence intervals that none have been detected during the past 10 years of GPS observations.