TELESEISMIC ESTIMATES OF THE ENERGY RADIATED BY SHALLOW EARTHQUAKES
TELESEISMIC ESTIMATES OF THE ENERGY RADIATED BY SHALLOW EARTHQUAKES
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DOI：
10.1029/jb091ib02p02095
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发表时间：
1986-02-10
期刊：
影响因子：
--
通讯作者：
CHOY, GL
中科院分区：
文献类型：
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作者：
BOATWRIGHT, J;CHOY, GL
模拟了浅层地震辐射的P波群(P+PP+SP)或S波群(S+PS+SS)中包含的能量通量，假定能量通量在直接相和深度相上非相干地增加。通过定义包含这种中性干扰的广义辐射模式，对波群进行分析，就好像它们是由单个相位组成的。对于记录的体波衰减和频带，波群中的能量通量的测量都在频域中进行了校正。然后使用校正后的测量值来估计地震辐射的地震能量。这一分析适用于1983年5月2日加利福尼亚州科林加地震和1983年10月28日爱达荷州波拉峰地震所辐射的远震波群的数字记录。对于科林加地震，从6个P波组中确定了Es=1.6±0.4×1021dyn cm，而在COL台记录的SH波组返回了Es=1.2×1021dyn cm。对于波拉峰地震，从7个波组中确定了Es=3.2±0.5×1021dyn cm。波拉峰地震的等震线分布表明，这次地震的辐射能量集中在西北方向，即破裂传播方向。对远震估计进行了修正，给出了Es=3.6±0.5×1021dyn cm。将这些辐射能量的估计与地震矩的宽带估计相结合，分别得到了Coalinga地震和Borah Peak地震的17巴和7巴的视应力估计。
The energy flux contained in theP‐wave groups (P+pP+sP) or theS‐wave groups (S+pS+sS) radiated by a shallow earthquake is modeled assuming that the energy flux in the direct and depth phases adds incoherently. By defining generalized radiation patterns which incorporate this neutral interference, the wave groups are analyzed as though they were comprised of a single phase. Measurements of the energy flux in the wave groups are corrected in the frequency domain for both the body‐wave attenuation and the frequency band of the recording. The corrected measurements are then used to estimate the seismic energy radiated by the earthquake. This analysis is applied to digital recordings of the teleseismic wave groups radiated by the May 2, 1983, Coalinga, California, earthquake and the October 28, 1983, Borah Peak, Idaho, earthquake. For the Coalinga earthquake, an estimate ofEs= 1.6 ± 0.4×1021dyn cm was determined from sixP‐wave groups, while theSHwave group recorded at station COL returned an estimate ofEs= 1.2×1021dyn cm. For the Borah Peak earthquake, an estimate ofEs= 3.2 ± 0.5×1021dyn cm was determined from sevenP‐wave groups. The distribution of the isoseismals for the Borah Peak earthquake indicate that the energy radiated by this event was focussed to the northwest, in the direction of rupture propagation. Correcting the teleseismic estimate for this focussing givesEs= 3.6 ± 0.5×1021dyn cm. Combining these estimates of the radiated energy with broad‐band estimates of the seismic moment yields estimates of the apparent stress of 17 and 7 bars for the Coalinga and the Borah Peak earthquakes, respectively.