Observing seismic and silent faulting related to a megathrust earthquake cycle: Joint application of InSAR and creepmeter ground displacement measurements

大陆边缘的会聚板块边界属于地球上构造最活跃的地区，是毁灭性地震和海啸的潜在来源。虽然大部分应变积累发生在俯冲界面上，但由于上覆地壳中的断层活动，发生了重大的危险变形。尽管有大量证据表明智利北部存在地表断裂，但上板块断裂与俯冲地震周期阶段之间的关系在很大程度上是未知的。在安托法加斯塔和阿里卡之间的地区，我们建议研究大地震前、中、后上板块的位移速率、变形机制和地表响应。将通过野外构造地貌学的方法研究过去的变形状态。该项目的核心是研究正在进行的形变状态，为此，我们将采用遥感和直接现场测量的方法。利用卫星雷达干涉测量(InSAR)，我们试图以厘米的分辨率探测断层上的地面位移。为了进行更精确的信号分析，我们建议在选定的断层位置使用蠕变仪，以便在亚毫米尺度上解决断层滑动的强度和时间变异性。这些方法的结合将允许在不同的尺度上调查现今的断层位移速率，并与长期地震旋回进行比较。最终，我们希望为智利弧前地区的间歇性和永久性应变积累开发一个综合模型。

Convergent plate boundaries at continental margins belong to the tectonically most active areas on earth and are the potential source of devastating earthquakes and tsunamis. While the bulk of strain accumulation occurs along the subduction interface, significant hazardous deformation occurs by fault activity in the overriding crust. Despite abundant evidence for surface faulting in northern Chile, it is largely unknown how upper plate faulting is related to stages of the subduction earthquake cycle. In the region between the cities Antofagasta and Arica, we propose to study the displacement rates and deformation mechanisms and surface response of the upper plate before, during and after large earthquakes. Past states of deformation will be studied by means of tectonic geomorphology in the field. The core of the project is then to study the ongoing state of deformation, for which we will apply methods of remote sensing and direct field measurements. Using satellite radar interferometry (InSAR) we attempt to detect ground displacements at faults at a resolution of centimetres. For an even more precise signal analysis we propose to use creepmeters at selected fault locations in order to resolve magnitude and temporal variability of fault slip at the submillimeter scale. The combination of these methods shall allow to investigate present fault displacement rates at various scales and to compare with the long term seismic cycle. Ultimately we want to develop an integrated model for episodic and permanent strain accumulation in the Chilean Forearc.