Reducing nonuniqueness in finite source inversion using rotational ground motions
Reducing nonuniqueness in finite source inversion using rotational ground motions
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DOI：
10.1002/2014jb011042
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发表时间：
2014-06-01
影响因子：
3.9
通讯作者：
Igel, H.
中科院分区：
文献类型：
--
作者：
Bernauer, M.;Fichtner, A.;Igel, H.
我们评估了旋转地震动记录在运动学震源反演中减少不唯一性的潜力，重点是当前开发的旋转传感器所需的测量精度。我们的分析基于综合贝叶斯有限源反演，避免了线性化，并提供了不确定性和权衡的全面量化。使用鸟取县2000年地震的断层和接收器几何结构作为试验台，我们对两个场景进行了反演：在场景I中，我们只使用平移速度记录。在场景II中，我们用旋转记录随机替换一半的速度记录，从而保持数据总量恒定。为了量化旋转记录的噪声相关影响，我们执行了一系列反转，其中相对于平移的旋转具有不同的噪声级别。我们的结果表明，在测量不确定度与平移速度记录的不确定度相似或更低的情况下，加入旋转地震动记录可以显著降低有限震源反演中的不唯一性。当满足这一条件时，破裂速度和上升时间从旋转数据中受益最大。然后，这两个参数之间的权衡就会大大减少，信息增益几乎翻了一番。这表明，旋转地震动记录可能会改进依赖于关于上升时间和破裂速度的准确信息的二次推断。这些因素包括断层的摩擦特性、辐射方向性和一般的地面运动。
We assess the potential of rotational ground motion recordings to reduce nonuniqueness in kinematic source inversions, with emphasis on the required measurement accuracy of currently developed rotation sensors. Our analysis is based on synthetic Bayesian finite source inversions that avoid linearizations and provide a comprehensive quantification of uncertainties and trade-offs. Using the fault and receiver geometry of the Tottori 2000 earthquake as a test bed, we perform inversions for two scenarios: In scenario I, we use translational velocity recordings only. In scenario II, we randomly replace half of the velocity recordings by rotation recordings, thus keeping the total amount of data constant. To quantify the noise-dependent impact of rotation recordings, we perform a sequence of inversions with varying noise levels of rotations relative to translations. Our results indicate that the incorporation of rotational ground motion recordings can significantly reduce nonuniqueness in finite source inversions, provided that measurement uncertainties are similar to or below the uncertainties of translational velocity recordings. When this condition is met, rupture velocity and rise time benefit most from rotation data. The trade-offs between both parameters are then strongly reduced, and the information gain nearly doubles. This suggests that rotational ground motion recordings may improve secondary inferences that rely on accurate information about rise time and rupture velocity. These include frictional properties of the fault, radiation directivity, and ground motion in general.