Estimation of high-frequency wave radiation areas on the fault plane by the envelope inversion of acceleration seismograms
Estimation of high-frequency wave radiation areas on the fault plane by the envelope inversion of acceleration seismograms
复制标题
加速度地震图包络线反演断层面高频波辐射区域估计
DOI：
10.1111/j.1365-246x.1996.tb06032.x
复制
发表时间：
1996
影响因子：
2.8
通讯作者：
K. Irikura
中科院分区：
文献类型：
--
作者：
Y. Kakehi;K. Irikura
我们开发了一种估算断裂面上高频波辐射面积的反演方法。对频率高于1hz的地震波形进行震源反演是非常困难的，因为有两个问题：一是难以获得对如此高的频率足够精确的格林函数，二是对这种振荡数据进行波形反演涉及到的问题。我们用余震记录作为经验格林函数，用加速度地震图包络层代替波形作为反演数据，克服了这些问题。包络线的计算是通过平滑加速度地震图和运行均方根时间窗。我们将这种方法应用于1993年日本钏路-大木地震（Mw= 7.6），该地震发生在太平洋板块俯冲至北美板块下方的水平断层上。我们采用MJMA 4.9级余震作为经验格林函数事件。我们对3个台站的强震加速度地震图进行了带通滤波（2.0-10.0 Hz），并以5.0 s窗长平滑计算包络线。将40 km × 60 km断层面划分为4 × 6个网格，通过反演得到每个网格的加速度辐射强度和破裂时间。结果如下：(1)高频波在破裂起点附近辐射较弱，主要在断裂面外围附近辐射。在断裂起点西南约30 km处的断裂面边缘处可见高频波辐射强度特别强的区域；它的大小约为20公里× 20公里。(2)高频辐射强度分布与滑移分布互为补充。也就是说，低频波弱的地方，高频波的辐射强。
We have developed an inversion method to estimate high-frequency wave radiation areas on the fault plane. It is very difficult to perform a source inversion for seismic waveforms whose frequencies are higher than 1 Hz because of two problems: one is the difficulty in obtaining Green's functions that are accurate enough for such high frequencies, and the other is that involved in doing a waveform inversion for such oscillatory data. We overcame these problems by using aftershock records as empirical Green's functions, and by using the envelopes of acceleration seismograms as the inversion data instead of waveforms. Envelopes were calculated by smoothing the acceleration seismograms with a running root-mean-square time window. We applied this method to the 1993 Kushiro-Oki, Japan, earthquake (Mw= 7.6), which occurred on a horizontal fault plane inside the Pacific Plate subducting beneath the North American Plate. We adopted the MJMA 4.9 aftershock as the empirical Green's function event. We bandpass-filtered (2.0–10.0 Hz) the strong-motion acceleration seismograms at three stations and calculated the envelopes by smoothing with a 5.0 s window length. The 40 km × 60 km fault plane was divided into 4 × 6 meshes, and the acceleration radiation intensity and rupture time of each mesh were obtained by the inversion. The results are as follows. (1) High-frequency waves radiated weakly around the rupture starting point, but radiated mainly near the periphery of the fault plane. an area with particularly strong radiation intensity of high-frequency waves is seen at the edge of the fault plane about 30 km southwest of the rupture starting point; its size is about 20 km × 20 km. (2) the distribution of high-frequency radiation intensity and slip distribution are complementary to each other. That is, the radiation of high-frequency waves was strong in those areas where that of low-frequency waves was weak.
DOI：
--
发表时间：
1975-10
期刊：
--
影响因子：
--
作者：
H. Kanamori;D. L. Anderson
通讯作者：
H. Kanamori;D. L. Anderson