In this article, we examine the 24 April 2014 Mw 6.4 earthquake offshore Vancouver Island using a surface‐wave empirical Green’s function (EGF) deconvolution method and compare the results with SeaJade II double‐difference aftershock locations. The 24 April event was well recorded and provides the first opportunity to evaluate the suitability of surface‐wave EGF deconvolution to constrain rupture details for moderate‐sized earthquakes in areas lacking dense seismic arrays. Our surface‐wave EGF deconvolution results agree with the aftershock distribution and previously determined centroid moment tensor results. This agreement suggests that this technique is valid for events of this magnitude in a sparsely networked region. We used an Mw 5.3 earthquake about 21 km from the 24 April epicenter as the primary EGF source event and applied stacking to improve the signal‐to‐noise ratio. Our analysis used broadband seismic data from 105 regional and teleseismic stations. Given the small magnitudes of these events, an aftershock (⁠Mw 4.8) was considered a secondary EGF source to verify key observations. The relative source time functions obtained from this study reveal an overall rupture direction of 143°±6°⁠, extent of 28±2 km⁠, and duration of 16.7±0.3 s⁠. We also determined that the rupture occurred in multiple, distinct subevents, but the deconvolution was unable to determine the subevent parameters. Double‐difference aftershock relocations using both onshore and offshore seismometers indicate a 32±2 km unilateral rupture with strike of 146°±2°⁠. These independently determined rupture parameters agree with previously determined centroid moment tensor results with a nodal plane striking 150°±6°⁠.

中文翻译：

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测试经验格林函数方法以确定2014年4月24日温哥华岛地震的破裂参数

在本文中，我们使用表面波经验格林函数（EGF）反卷积方法研究了温哥华岛2014年4月24日发生的6.4级地震，并将结果与​​SeaJade II双差余震位置进行了比较。4月24日的事件得到了很好的记录，并为评估表面波EGF反褶积是否适合约束缺乏密集地震阵列的中等规模地震的破裂细节提供了第一个机会。我们的表面波EGF反褶积结果与余震分布和先前确定的质心矩张量结果一致。该协议表明，该技术适用于稀疏网络区域中这种规模的事件。我们使用了Mw 5。从4月24日震中开始约21公里的3级地震是EGF的主要事件，并应用叠加技术提高了信噪比。我们的分析使用了来自105个区域和远程地震台站的宽带地震数据。鉴于这些事件的规模较小，余震（Mw 4.8）被认为是EGF的次要来源，以验证关键观测结果。从这项研究中获得的相对震源时间函数显示出总破裂方向为143°±6°⁠，范围为28±2km⁠，持续时间为16.7±0.3s⁠。我们还确定了破裂发生在多个不同的子事件中，但是反卷积无法确定子事件参数。使用陆上和海上地震仪进行的双差余震定位表明，单侧破裂为32±2 km，走向为146°±2°⁠。