Capturing seismic velocity changes in receiver functions with optimal transport
Capturing seismic velocity changes in receiver functions with optimal transport
复制标题
通过最佳传输捕获接收器函数中的地震速度变化
DOI：
10.1093/gji/ggad130
复制
发表时间：
2023
影响因子：
2.8
通讯作者：
Audet, Pascal
中科院分区：
文献类型：
--
作者：
Bryan, Jared;Frank, William B.;Audet, Pascal
地震波速度的时间变化是追踪地壳瞬时变形期间结构变化的重要工具。虽然许多地球物理过程跨越地壳，包括火山动荡和大规模地震，但现有的地震监测方法仅限于浅层地下。我们提出了一种基于自下而上的地壳速度结构的地震监测方法。使用合成波形建模，我们表明，接收器的功能是一致的速度变化在整个地壳敏感，可以定位的扰动的深度。本文提出了一种基于最优传输的非线性时幅信号变化特性的测量方法。我们表明，最佳的运输，使比较完整的波形分布，而不是依赖于代表性的堆叠波形。我们进一步研究了最优传输的线性化版本，该版本将时间扭曲信号变化呈现为简单的欧几里得扰动，并使用这种能力在波形变化的空间中执行盲源分离。这将震源-接收器路径变化的影响与地下速度变化的影响区分开来。总的来说，这些方法将地震监测的范围扩展到深部地球物理过程，并提供了一种工具，可用于研究具有不同空间范围和时间动态的非均匀速度变化。
Temporal changes in seismic velocities are an important tool for tracking structural changes within the crust during transient deformation. Although many geophysical processes span the crust, including volcanic unrest and large-magnitude earthquakes, existing methods for seismic monitoring are limited to the shallow subsurface. We present an approach for deep seismic monitoring based on teleseismic receiver functions, which illuminate the crustal velocity structure from the bottom-up. Using synthetic waveform modelling, we show that receiver functions are uniformly sensitive to velocity changes throughout the crust and can locate the depth of the perturbation. We introduce a novel method based on optimal transport for measuring the non-linear time–amplitude signal variations characteristic of receiver function monitoring. We show that optimal transport enables comparison of full waveform distributions rather than relying on representative stacked waveforms. We further study a linearized version of optimal transport that renders time-warping signal variations into simple Euclidean perturbations, and use this capability to perform blind source separation in the space of waveform variations. This disentangles the effects of changes in the source–receiver path from changes in subsurface velocities. Collectively, these methods extend the reach of seismic monitoring to deep geophysical processes, and provide a tool that can be used to study heterogeneous velocity changes with different spatial extents and temporal dynamics.