SEISMIC IMAGING OF EARTHQUAKE FAULTS USING EARTH’S AMBIENT VIBRATIONS
Seismic velocity and attenuation are key characteristics that describe how seismic waves propagate within the earth. The former refers to the speed of wave propagation, while the latter is an inherent property of rocks that leads to energy dissipation as waves traverse the subsurface. We have developed new methods, specifically ambient noise differential adjoint/attenuation tomography using a linear triplet of stations, to examine the velocity/attenuation structure beneath linear seismic arrays. Our results reveal slow S-wave velocity structures corresponding to fluid-bearing rocks such as the Silverado Aquifer near the Newport-Inglewood Fault section in Long Beach, California, which agree with the week-long seismicity along the fault detected by a deep learning-based denoising method. The attenuation tomography results for Southern California and Longmenshan Fault Zone highlight a correlation between strong attenuation and fault damage zones.
Additional information: Dr. Xin LIU, liuxine@hku.hk