We summarize estimates of the maximum rupture depth on New Zealand’s active faults (“New Zealand Fault‐Rupture Depth Model v.1.0”), as used in the New Zealand Community Fault Model v1.0 and as a constraint for the latest revision of the New Zealand National Seismic Hazard Model (NZ NSHM 2022). Rupture depth estimates are based on a combination of two separate model approaches (using different methods and datasets). The first approach uses regional seismicity distribution from a relocated earthquake catalog to calculate the 90% seismicity cutoff depth (D90), representing the seismogenic depth limit. This is multiplied by an overshoot factor representing the dynamic propagation of rupture into the conditional stability zone, and accounting for the difference between regional seismicity depths and the frictional properties of a mature fault zone to arrive at a seismic estimate of the maximum rupture depth. The second approach uses surface heat flow and rock type to compute depths that correspond to the thermal limits of frictional instabilities on seismogenic faults. To arrive at a thermally‐based maximum rupture depth, these thermal limits are also multiplied by an overshoot factor. Both the models have depth cutoffs at the Moho and/or subducting slabs. Results indicate the maximum rupture depths between 8 (Taupō volcanic zone) and >30 km (e.g., southwest North Island), strongly correlated with regional thermal gradients. The depths derived from the two methods show broad agreement for most of the North Island and some differences in the South Island. A combined model using weighting based on relative uncertainties is derived and validated using constraints from hypocenter and slip model depths from recent well‐instrumented earthquakes. We discuss modifications to the maximum rupture depths estimated here that were undertaken for application within the NZ NSHM 2022. Our research demonstrates the utility of combining seismicity cutoff and thermal stability estimates to assess the down‐dip dimensions of future earthquake ruptures.

中文翻译：

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新西兰断层破裂深度模型 v.1.0：新西兰活断层地震破裂最大深度的临时估计

我们总结了新西兰活动断层最大破裂深度的估计（“新西兰断层破裂深度模型 v.1.0”），用于新西兰社区断层模型 v1.0 中，并作为最新修订的约束新西兰国家地震灾害模型 (NZ NSHM 2022)。破裂深度估计基于两种独立模型方法的组合（使用不同的方法和数据集）。第一种方法使用重新定位的地震目录中的区域地震活动分布来计算 90% 地震活动截止深度 (D90)，代表地震深度限制。将其乘以代表破裂动态传播到条件稳定区的超调因子，并考虑区域地震活动深度和成熟断层带摩擦特性之间的差异，以获得最大破裂深度的地震估计。第二种方法使用地表热流和岩石类型来计算与发震断层摩擦不稳定性热极限相对应的深度。为了达到基于热的最大破裂深度，这些热限制还要乘以超调因子。这两个模型在莫霍面和/或俯冲板片处都有深度截止。结果表明最大破裂深度在 8 公里（陶波火山带）和 > 30 公里（例如北岛西南部）之间，与区域热梯度密切相关。两种方法得出的深度显示出北岛大部分地区的广泛一致性，以及南岛的一些差异。使用基于相对不确定性的加权的组合模型是使用来自最近仪器仪表齐全的地震的震源和滑移模型深度的约束来导出和验证的。我们讨论了对此处估计的最大破裂深度的修改，这些修改是在 NZ NSHM 2022 中应用的。我们的研究证明了将地震活动截止和热稳定性估计相结合来评估未来地震破裂的下倾尺寸的效用。