Characterizing Afterslip and Ground Displacement Rate Increase Following the 2014 Iquique-Pisagua Mw 8.1 Earthquake, Northern Chile
Characterizing Afterslip and Ground Displacement Rate Increase Following the 2014 Iquique-Pisagua Mw 8.1 Earthquake, Northern Chile
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DOI：
10.1002/2017jb014970
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发表时间：
2018-05-01
影响因子：
3.9
通讯作者：
Oncken, Onno
中科院分区：
文献类型：
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作者：
Hoffmann, Felix;Metzger, Sabrina;Oncken, Onno
2014年伊基克-皮萨瓜M-w 8.1地震仅破坏了1877年智利北方-秘鲁南部地震空区的部分地区。在这里，我们提出了一个全面的分析，152个连续的和运动的全球定位系统的时间序列，捕获超过十年的地震间的负载之前的事件和2年的后滑。在高时空分辨率，我们的数据文件上板块的响应不仅在同震影响的纬度，但也在相邻的洛亚板块段南部。使用弹性和粘弹性半空间模型的地震周期的不同阶段的组合，我们发现，高度耦合，前地震空区包含一个狭窄的低耦合区在21度S纬度。在2014年地震之后，这个区域就像一个屏障，阻止后滑继续向南。造成这一障碍的可能原因可能涉及地壳的不均匀性或板块界面的耦合不连续性。2年后，后滑累积到最大值89厘米，可以忽略不计。全球定位系统的观测推断地震构造障碍南部显示，在事件发生后的第二年，变形率增加。我们的滑动模型表明，这可能是由于下倾耦合增加，也许使高度耦合的南部洛阿段更接近失败。结果表明：（1）在一个主要地震空区中，应力释放和应力积累的不同区域之间存在相互作用;（2）在地震周期的不同阶段，耦合度随时间变化的制约因素;（3）相邻段大地震的影响。
The 2014 Iquique-Pisagua M-w 8.1 earthquake ruptured only parts of the 1877 Northern Chile-Southern Peru seismic gap. Here we present a comprehensive analysis of 152 continuous and campaign Global Positioning System time series that captured more than a decade of interseismic loading prior to the event and 2 years of afterslip. In high spatiotemporal resolution, our data document upper plate response not only at the coseismically affected latitudes but also at the adjacent Loa plate segment to the south. Using a combination of elastic and viscoelastic half-space models of different stages of the seismic cycle, we found that the highly coupled, former seismic gap contains a narrow low coupling zone at 21 degrees S latitude. Just after the 2014 earthquake, this zone acts as a barrier impeding afterslip to continue southward. Possible reasons for this impediment could involve crustal heterogeneities or coupling discontinuities at the plate interface. After 2 years, afterslip cumulates to a maximum of similar to 89 cm and becomes negligible. Global Positioning System observations south of the inferred seismotectonic barrier reveal a deformation rate increase in the second year after the event. Our slip models suggest that this could be caused by a downdip coupling increase, perhaps bringing the highly coupled southern Loa segment closer to failure. Taken together, our results reveal (1) the interaction between different areas undergoing stress release and stress buildup in a major seismic gap, (2) constraints for the temporal variation of coupling degree in different stages of the seismic cycle, and (3) the influence of large earthquakes at adjacent segments.