Imaging short-period seismic radiation from the 27 February 2010 Chile (MW 8.8) earthquake by back-projection of P, PP, and PKIKP waves
Imaging short-period seismic radiation from the 27 February 2010 Chile (MW 8.8) earthquake by back-projection of P, PP, and PKIKP waves
复制标题
DOI：
10.1029/2011jb008576
复制
发表时间：
2012-02-18
影响因子：
3.9
通讯作者：
Sufri, Oner
中科院分区：
文献类型：
--
作者：
Koper, Keith D.;Hutko, Alexander R.;Sufri, Oner
2010 年 2 月 27 日智利地震 (M-w 8.8) 的远震短周期 (0.5-5 s) P 波被反向投影到震源区域，以对相干短周期地震波辐射的位置进行成像。使用不同的 P 波到达分析了几种接收机阵列配置，包括北美 (P)、日本 (PKIKP) 和欧洲 (PP) 的台站网络，以及具有宽方位角分布和较长周期 P 波（5-20 s）的全球台站配置。来自源头的短周期辐射的相干爆发集中在智利海岸线下方，沿着巨型逆冲断层的下倾部分。短周期源区向两侧扩展，辐射具有明显的不规则性。与长周期地震波反演的有限断层滑移模型的比较表明，巨型逆冲断层上的大滑移区域位于短周期辐射区域的上倾位置，这是频率依赖的地震辐射的表现，类似于2011年东北大地震（M-w 9.0）的观测结果。由有限断层模型生成的合成 P 波的反投影表明，如果短周期能量以与长周期能量相同的时空分布辐射，则反投影分析会将其成像在正确的位置（上倾）。我们得出的结论是，短周期信号的反投影成像提供了震源的清晰视图，而仅基于长周期地震波、大地测量数据和/或海啸观测的研究则忽略了这一点。
Teleseismic short-period (0.5-5 s) P waves from the 27 February 2010 Chile earthquake (M-w 8.8) are back projected to the source region to image locations of coherent short-period seismic wave radiation. Several receiver array configurations are analyzed using different P wave arrivals, including networks of stations in North America (P), Japan (PKIKP), and Europe (PP), as well as a global configuration of stations with a broad azimuthal distribution and longer-period P waves (5-20 s). Coherent bursts of short-period radiation from the source are concentrated below the Chilean coastline, along the downdip portion of the megathrust. The short-period source region expands bilaterally, with significant irregularity in the radiation. Comparison with finite fault slip models inverted from longer-period seismic waves indicates that the regions of large slip on the megathrust are located updip of the regions of short-period radiation, a manifestation of frequency-dependent seismic radiation, similar to observations for the great 2011 Tohoku earthquake (M-w 9.0). Back projection of synthetic P waves generated from the finite fault models demonstrates that if the short-period energy had radiated with the same space-time distribution as the long-period energy, back-projection analysis would image it in the correct location, updip. We conclude that back-projection imaging of short-period signals provides a distinct view of the seismic source that is missed by studies based only on long-period seismic waves, geodetic data, and/or tsunami observations.