The largest earthquakes in subduction zones occur where significant interseismic slip deficit has accumulated on the plate interface. Slip deficit accumulates most quickly in mechanically locked regions, and these also cause the regions around them to accumulate slip deficit; therefore, large earthquakes are typically expected to rupture in and around locked areas. The locations and dimensions of these locked zones have been difficult to resolve using standard techniques and available data sets. We develop a new statistical interseismic inversion approach that incorporates the physical interactions between nearby fault areas to directly determine the distribution of locking on the subduction plate interface (simultaneously with rigid forearc motions) from interseismic surface velocities. Because we include physical prior information in the inversion procedure, this approach reduces uncertainties in the rate of slip deficit accumulation, even in locations (such as near the trench) where kinematic inversions of onshore data have relatively low resolution. Applying the inversion to the South America subduction zone, we find that the pattern of locking and corresponding slip deficit rates correlate well with recent and historical large earthquake ruptures. Locked patch dimensions are <40 km and account for no more than 30% of the area of the plate interface. The small size of the imaged locked zones is a natural outcome of our physical assumptions and implies that mechanical locking is caused by correspondingly small geological features. Despite their small dimensions, locked zones generate substantial slip deficit on the surrounding plate interface, consistent with the slip patterns of large megathrust earthquakes.

中文翻译：

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沿着南美洲俯冲巨推力定位完全锁定的凹凸不平：贝叶斯框架中的一种新的物理间震反演方法

俯冲带最大的地震发生在板块界面上积累了明显的地震间滑动缺损的地方。滑移缺陷在机械锁定区域中的堆积速度最快，这也会导致其周围区域积聚滑移缺陷。因此，通常预期大地震会在锁定区域内和附近破裂。使用标准技术和可用数据集很难解析这些锁定区域的位置和尺寸。我们开发了一种新的统计间震反演方法，该方法结合了附近断层区域之间的物理相互作用，以根据间震表面速度直接确定俯冲板界面上的锁定分布（同时进行刚性前臂运动）。因为我们在反演过程中包括了先验物理信息，所以即使在陆上运动学反演具有相对较低分辨率的位置（如海沟附近），这种方法也可以减少滑差累积速率的不确定性。将反演应用于南美俯冲带，我们发现锁定的模式和相应的滑脱率与近期和历史的大地震破裂有很好的相关性。锁定的补片尺寸小于40 km，且不超过板接口面积的30％。成像锁定区的小尺寸是我们物理假设的自然结果，并且暗示机械锁定是由相应的较小地质特征引起的。尽管尺寸很小，