Temporal changes in the subsurface seismic velocity structure reflect the physical processes that modulate the properties of the media through which seismic waves propagate. These processes, such as healing of the surface damage zone and deep crustal deformation, are described by similar functional forms and operate on similar timescales, making it difficult to determine which process drives the observed changes. We examine earthquake‐induced velocity changes using the measured lag‐time time series τ (t ) of the repeating earthquake sequences since the 2004 M _w 9.2 Sumatra and 2005 M _w 8.6 Nias earthquakes. The S coda velocity changes (δV _S, equivalent to −τ _S) recover steadily during the 2005–2015 period. The Rayleigh wave velocity changes (δV _LR, or −τ _LR) undergo transient recovery, followed by a strong δV _LR reduction in late 2007. δV _S recovery is most likely driven by deep processes, whereas the temporal breaks in δV _LR recovery in 2007 mostly reflect surface damage and healing induced by the strong ground motions of the 2004 M _w 9.2, 2005 M _w 8.6, 2007 M _w 8.4, and M _w 7.9 Bengkulu and 2008 M _w 7.3 Simeulue earthquakes. The observed differences between the temporal variations in δV _S and δV _LR can distinguish deep processes from healing of the surface damage zone.

中文翻译：

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十年来反复发生的S尾波和瑞利波揭示了自2004年苏门答腊地震以来不协调的时间速度变化

地下地震速度结构的时间变化反映了物理过程，这些物理过程调节了地震波通过其传播的介质的特性。这些过程，例如表面损伤区的愈合和地壳深部变形，以相似的功能形式描述，并且以相似的时间尺度运行，因此很难确定哪个过程驱动了观察到的变化。我们研究使用所测量的滞后时间的时间序列地震引起速度变化τ（吨的重复地震序列的）自2004年中号_瓦特9.2苏门答腊和2005中号_瓦特8.6尼亚斯地震。该小号尾波的速度变化（δV_小号，相当于-τ_小号）在2005 - 2015年期间稳定复苏。瑞利波的速度变化（δV _LR，或-τ _LR）经历瞬态恢复，接着是强δV _LR在2007年底减少δV_小号恢复很可能是由深部过程驱动的，而在所述时间中断δV _LR 2007恢复主要反映了2004 M _W 9.2、2005 M _W 8.6、2007 M _W 8.4和M _W的强地面运动引起的表面损伤和愈合7.9明古鲁和2008年中号_W¯¯ 7.3锡默卢地震。在时间变化之间的观察到的差异δV_小号和δV _LR可以从表面损伤区的愈合区分深部过程。