Hypocenter Hotspots Illuminated Using a New Cross‐Correlation‐Based Hypocenter and Centroid Relocation Method
Hypocenter Hotspots Illuminated Using a New Cross‐Correlation‐Based Hypocenter and Centroid Relocation Method
复制标题
使用新的基于互相关的震源和质心重定位方法照亮震源热点
DOI：
10.1029/2021jb021991
复制
发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Ide Satoshi
中科院分区：
文献类型：
--
作者：
Chang Ta‐Wei;Ide Satoshi
准确的地震定位对于了解地震过程非常重要。最近在地震重定位方法的进展，导致相对质心位置较小的不确定性，使用互相关为基础的方法。然而，相对震源位置，这是传统上使用的事件波形的起始时间确定，通常具有更大的不确定性比的质心。在这里，我们开发了一种新的基于互相关的相对震源重定位方法，该方法基于网络相关系数方法，由此我们引入了一个额外的步骤来搜索合适的窗口以互相关事件波形发作。然后，我们进行联合反演所获得的相对震源和质心位置直接比较它们的相对位置下一个统一的坐标。我们将这种方法应用于三个地区，重复地震已被检测到，并揭示了这些重复的事件和新照亮的震源热点，作为发病地区的地震，成长为不同的，但选择性的震级类似的质心的重复破裂。我们的震源和质心位置的联合分析，使破裂传播方向的快速估计，而不需要进行滑动反演分析。我们通过自举估计位置不确定性，95%置信区间在质心和震源位置产生低于100米的水平不确定性，具有最佳的台站覆盖和事件可用性。这些结果指出，有限的，但现有的对应关系的震源和质心的位置和地震震级，以及复杂的震源分布，即使在重复的地震序列的破裂区域很大程度上重叠。
Accurate earthquake locations are important for understanding earthquake processes. Recent advances in earthquake relocation methods have resulted in relative centroid locations with smaller uncertainties using cross‐correlation‐based methods. However, relative hypocenter locations, which are traditionally determined using the onset times of event waveforms, generally possess larger uncertainties than that of the centroids. Here, we develop a new cross‐correlation‐based relative hypocenter relocation method based on the network correlation coefficient method, whereby we incorporate an additional step to search for a suitable window to cross‐correlate the event waveform onsets. We then perform a joint inversion on the obtained relative hypocenter and centroid locations to directly compare their relative locations under a unified coordinate. We apply this method to three regions where repeating earthquakes have been detected, and reveal both the repetitive rupture of similar centroids by these repeating events and newly illuminated hypocenter hotspots that serve as the onset region of earthquakes that grow into different but selective magnitudes. Our joint analysis of hypocenter and centroid locations enables quick estimations of rupture propagation directions without the need to perform slip inversion analyses. We estimate the location uncertainties via bootstrapping, with the 95% confidence intervals yielding sub‐100 m horizontal uncertainties in both the centroid and hypocenter locations with the best station coverage and event availability. These results point to limited but existing correspondence between the hypocenter and centroid locations and the earthquake magnitudes, as well as complexity in the hypocenter distributions, even within repeating earthquake sequences whose rupture areas largely overlap.