Knowledge of the locations of seismic sources is critical for microseismic monitoring. Time-window-based elastic wave interferometric imaging and weighted- elastic-wave （WEW） interferometric imaging are proposed and...Knowledge of the locations of seismic sources is critical for microseismic monitoring. Time-window-based elastic wave interferometric imaging and weighted- elastic-wave （WEW） interferometric imaging are proposed and used to locate modeled microseismic sources. The proposed method improves the precision and eliminates artifacts in location profiles. Numerical experiments based on a horizontally layered isotropic medium have shown that the method offers the following advantages： It can deal with Iow-SNR microseismic data with velocity perturbations as well as relatively sparse receivers and still maintain relatively high precision despite the errors in the velocity model. Furthermore, it is more efficient than conventional traveltime inversion methods because interferometric imaging does not require traveltime picking. Numerical results using a 2D fault model have also suggested that the weighted-elastic-wave interferometric imaging can locate multiple sources with higher location precision than the time-reverse imaging method.展开更多
Based on horizontal-component digital seismograms recorded on 6 stations of the Yunnan Regional Digital Network, we inversed the inelastic attenuation in the source region of the Shidian swarm using the Atkinson metho...Based on horizontal-component digital seismograms recorded on 6 stations of the Yunnan Regional Digital Network, we inversed the inelastic attenuation in the source region of the Shidian swarm using the Atkinson method and the site responses of the 6 stations 200kin around the Shidian epicenters using the Moya method. The observational seismic waveform data were corrected by removing the propagation, instrument and site effects before the source parameters of the Shidian swarm in 2001 were determined using genetic algorithms. The results are as follows： （ 1 ） There is a linear relation between seismic moment and local magnitude. The seismic moment is between 1×10^12 and 10^14 N·m. The rupture radius of the seismic focus varies from 157m to 973m. The seismic moment and the rupture radius maintain a linear correlation. （2） The corner frequency increases as the seismic moment decreases. Based on the expression between corner frequency and seismic moment using least squares fitting, we can obtain the estimated value of the corner frequency. The time-varying value of the calculated corner frequency minus the estimated corner frequency shows that there were continuous high and low anomalies before the strong aftershocks. （3） The seismic stress drop is in the range of 0.07-1.55MPa. The stress drop seems independent of the local magnitude. The variation of stress drops is high before the occurrence of the strong aftershocks. （4） The depth of aftershocks is mostly in a range from 5kin to 10km, which means that energy release of aftershocks is mainly concentrated in this range of depth.展开更多
基金supported by the R&D of Key Instruments and Technologies for Deep Resources Prospecting(No.ZDYZ2012-1)National Natural Science Foundation of China(No.11374322)
文摘Knowledge of the locations of seismic sources is critical for microseismic monitoring. Time-window-based elastic wave interferometric imaging and weighted- elastic-wave （WEW） interferometric imaging are proposed and used to locate modeled microseismic sources. The proposed method improves the precision and eliminates artifacts in location profiles. Numerical experiments based on a horizontally layered isotropic medium have shown that the method offers the following advantages： It can deal with Iow-SNR microseismic data with velocity perturbations as well as relatively sparse receivers and still maintain relatively high precision despite the errors in the velocity model. Furthermore, it is more efficient than conventional traveltime inversion methods because interferometric imaging does not require traveltime picking. Numerical results using a 2D fault model have also suggested that the weighted-elastic-wave interferometric imaging can locate multiple sources with higher location precision than the time-reverse imaging method.
基金the State Science and Technology Programof Tackle Key Problemfor the tenth "Five-Year Plan" of China (2004BA601B01-04-03) and the Youth Fund of Earthquake Administration of Yunnan Province ,China
文摘Based on horizontal-component digital seismograms recorded on 6 stations of the Yunnan Regional Digital Network, we inversed the inelastic attenuation in the source region of the Shidian swarm using the Atkinson method and the site responses of the 6 stations 200kin around the Shidian epicenters using the Moya method. The observational seismic waveform data were corrected by removing the propagation, instrument and site effects before the source parameters of the Shidian swarm in 2001 were determined using genetic algorithms. The results are as follows： （ 1 ） There is a linear relation between seismic moment and local magnitude. The seismic moment is between 1×10^12 and 10^14 N·m. The rupture radius of the seismic focus varies from 157m to 973m. The seismic moment and the rupture radius maintain a linear correlation. （2） The corner frequency increases as the seismic moment decreases. Based on the expression between corner frequency and seismic moment using least squares fitting, we can obtain the estimated value of the corner frequency. The time-varying value of the calculated corner frequency minus the estimated corner frequency shows that there were continuous high and low anomalies before the strong aftershocks. （3） The seismic stress drop is in the range of 0.07-1.55MPa. The stress drop seems independent of the local magnitude. The variation of stress drops is high before the occurrence of the strong aftershocks. （4） The depth of aftershocks is mostly in a range from 5kin to 10km, which means that energy release of aftershocks is mainly concentrated in this range of depth.
