An M6.5 earthquake occurred on August 3rd, 2014 in Ludian of Yunnan Province in China, causing severe casualty and economic loss. Local broadband waveform inversion with the CAP method demonstrates that the earthquake...An M6.5 earthquake occurred on August 3rd, 2014 in Ludian of Yunnan Province in China, causing severe casualty and economic loss. Local broadband waveform inversion with the CAP method demonstrates that the earthquake is a strike-slip event, with the strike along 70° and 160° for the two nodal planes respectively. However, the geological structure in the epicentral region is complicated with abundant active faults, and it is challenging to identify the seismogenic fault with the focal plane solutions due to nodal-plane ambiguity. We resolved the rupture directivity by measuring the difference between centroid location and hypocenter of the Ludian earthquake with the time shift from CAP inversion, and found that the nodal plane with the strike of 160° is the ruptured fault plane. Moreover, the rupture is found to propagate from northwest to southeast.展开更多
The partial derivative equations of Zoeppritz equations are established and the derivatives of each matrix entry with respect to wave vectors are derived in this paper.By solving the partial derivative equations we ob...The partial derivative equations of Zoeppritz equations are established and the derivatives of each matrix entry with respect to wave vectors are derived in this paper.By solving the partial derivative equations we obtained the partial derivatives of seismic wave reflection coefficients with respect to wave vectors,and computed the Goos-Hnchen shift for reflected P-and VS-waves.By plotting the curves of Goos-Hnchen shift,we gained some new insight into the lateral shift of seismic reflection wave.The lateral shifts are very large for glancing wave or the wave of the incidence angle near the critical angle,meaning that the seismic wave propagates a long distance along the reflection interface before returning to the first medium.For the reflection waves of incidence angles away from the critical angle,the lateral shift is in the same order of magnitude as the wavelength.The lateral shift varies significantly with different reflection interfaces.For example,the reflected P-wave has a negative shift at the reflection interface between mudstone and sandstone.The reflected VS-wave has a large lateral shift at or near the critical angle.The lateral shift of the reflected VS-wave tends to be zero when the incidence angle approaches 90°.These observations suggest that Goos-Hnchen effect has a great influence on the reflection wave of wide-angles.The correction for the error caused by Goos-Hnchen effect,therefore,should be made before seismic data processing,such as the depth migration and the normal-moveout correction.With the theoretical foundation established in this paper,we can further study the correction of Goos-Hnchen effect for the reflection wave of large incidence angle.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.41274069)National Basic Research Program of China(Grant No.2014CB845901)
文摘An M6.5 earthquake occurred on August 3rd, 2014 in Ludian of Yunnan Province in China, causing severe casualty and economic loss. Local broadband waveform inversion with the CAP method demonstrates that the earthquake is a strike-slip event, with the strike along 70° and 160° for the two nodal planes respectively. However, the geological structure in the epicentral region is complicated with abundant active faults, and it is challenging to identify the seismogenic fault with the focal plane solutions due to nodal-plane ambiguity. We resolved the rupture directivity by measuring the difference between centroid location and hypocenter of the Ludian earthquake with the time shift from CAP inversion, and found that the nodal plane with the strike of 160° is the ruptured fault plane. Moreover, the rupture is found to propagate from northwest to southeast.
基金supported by Funding Project for Academic Human Resources Development in Institutions of Higher Learning (Grant No. PHR201107145)
文摘The partial derivative equations of Zoeppritz equations are established and the derivatives of each matrix entry with respect to wave vectors are derived in this paper.By solving the partial derivative equations we obtained the partial derivatives of seismic wave reflection coefficients with respect to wave vectors,and computed the Goos-Hnchen shift for reflected P-and VS-waves.By plotting the curves of Goos-Hnchen shift,we gained some new insight into the lateral shift of seismic reflection wave.The lateral shifts are very large for glancing wave or the wave of the incidence angle near the critical angle,meaning that the seismic wave propagates a long distance along the reflection interface before returning to the first medium.For the reflection waves of incidence angles away from the critical angle,the lateral shift is in the same order of magnitude as the wavelength.The lateral shift varies significantly with different reflection interfaces.For example,the reflected P-wave has a negative shift at the reflection interface between mudstone and sandstone.The reflected VS-wave has a large lateral shift at or near the critical angle.The lateral shift of the reflected VS-wave tends to be zero when the incidence angle approaches 90°.These observations suggest that Goos-Hnchen effect has a great influence on the reflection wave of wide-angles.The correction for the error caused by Goos-Hnchen effect,therefore,should be made before seismic data processing,such as the depth migration and the normal-moveout correction.With the theoretical foundation established in this paper,we can further study the correction of Goos-Hnchen effect for the reflection wave of large incidence angle.
