The potential for future earthquakes on faults is often inferred from inversions of geodetically derived surface velocities for locking on faults using kinematic models such as block models. This can be challenging in complex deforming zones with many closely spaced faults or where deformation is not readily described with block motions. Furthermore, surface strain rates are more directly related to coupling on faults than surface velocities. We present a methodology for estimating slip deficit rate directly from strain rate and apply it to New Zealand for the purpose of incorporating geodetic data in the 2022 revision of the New Zealand National Seismic Hazard Model. The strain rate inversions imply slightly higher slip deficit rates than the preferred geologic slip rates on sections of the major strike-slip systems including the Alpine Fault, the Marlborough Fault System and the northern part of the North Island Fault System. Slip deficit rates are significantly lower than even the lowest geologic estimates on some strike-slip faults in the southern North Island Fault System near Wellington. Over the entire plate boundary, geodetic slip deficit rates are systematically higher than geologic slip rates for faults slipping less than one mm/yr but lower on average for faults with slip rates between about 5 and 25 mm/yr. We show that 70%–80% of the total strain rate field can be attributed to elastic strain due to fault coupling. The remaining 20%–30% shows systematic spatial patterns of strain rate style that is often consistent with local geologic style of faulting.

中文翻译：

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复杂变形区滑移赤字率反演大地应变率：在新西兰板块边界的应用

断层上未来发生地震的可能性通常是通过大地测量得出的表面速度的反演来推断的，以便使用运动学模型（例如块模型）锁定断层。在具有许多紧密间隔断层的复杂变形区域或变形不易用块体运动描述的情况下，这可能具有挑战性。此外，表面应变率与断层耦合的关系比表面速度更直接。我们提出了一种直接根据应变率估算滑移赤字率的方法，并将其应用于新西兰，以便将大地测量数据纳入新西兰国家地震灾害模型 2022 年修订版中。应变率反演意味着主要走滑系统部分（包括阿尔卑斯断层、马尔堡断层系统和北岛断层系统北部）的滑移赤字率略高于首选地质滑移率。惠灵顿附近北岛南部断层系统的一些走滑断层的滑动赤字率甚至比最低的地质估计值还要低。在整个板块边界上，对于滑动率小于 1 毫米/年的断层，大地测量滑动缺失率系统地高于地质滑动率，但对于滑动率在 5 至 25 毫米/年之间的断层来说，大地滑动缺失率平均较低。我们表明，总应变率场的 70%–80% 可归因于断层耦合引起的弹性应变。剩下的20%~30%显示了应变率样式的系统空间模式，通常与当地断层地质样式一致。