We investigated seismic velocity changes (dv/v) associated with the 2019 Ridgecrest earthquake sequence with high‐frequency autocorrelations of ambient seismic noise data. Daily autocorrelation functions were computed for the entirety of 2019 and the first quarter of 2020 for broadband stations within the region, including the temporary broadband stations installed during the aftershock deployment. Travel time shifts in the daily autocorrelation functions, relative to the mean autocorrelation waveform, were computed to produce dv/v time series, which are sensitive to the evolving material properties of the shallow crust surrounding the Ridgecrest fault zone (RFZ). A short‐term velocity drop follows the M_w 7.1 earthquake at stations in the vicinity of the rupture surface, while those greater than 50 km away showed no such drop. The maximum, absolute changes in seismic velocity are proportional to the logarithm of distance from the fault rupture and to the peak dynamic strain experienced during the earthquake. Near the areas of the highest coseismic slip within the RFZ, seismic velocities recovered over 3 months. However, in the vicinity of the nearby Garlock fault, where triggered slip manifested, and north of the RFZ, seismic velocities recovered within a month. We interpret the seismic velocity changes and their recovery to be largely due to changes in the physical properties of the shallow crust, such as fault zone damage recovery caused by the earthquake rupture process and in response to the large dynamic stresses of passing seismic waves from the mainshock.

中文翻译：

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时间地震速度变化：2019年Mw 7.1里奇克莱斯特地震后的恢复

我们调查了与2019年Ridgecrest地震序列相关的地震速度变化（dv / v），并与周围地震噪声数据进行了高频自相关。计算了该区域内宽带站的整个2019年和2020年第一季度的每日自相关函数，包括余震部署期间安装的临时宽带站。相对于平均自相关波形，计算了每日自相关函数中的传播时间偏移，以产生dv / v时间序列，该时间序列对围绕Ridgecrest断层带（RFZ）的浅层地壳的演化物质特性敏感。短期速度下降跟随M _w7.1在破裂面附近的站点发生地震，而那些距离超过50 km的站点则没有这种下降。地震速度的最大绝对变化与断层破裂距离的对数以及地震中经历的峰值动态应变成正比。在RFZ内同震滑动最大的区域附近，地震速度在3个月内恢复了。然而，在附近的加洛克断层附近，那里显示出触发的滑动，并且在RFZ以北，地震速度在一个月内恢复了。我们将地震速度的变化及其恢复解释为很大程度上是由于浅层地壳的物理性质发生了变化，