Stress Drop Measurements of Induced Earthquakes in Delaware Basin, Texas

Session: Mechanisms of Induced Seismicity: Pressure Diffusion, Elastic Stressing and Aseismic Slip [Poster]
Type: Poster
Date: 4/29/2020
Time: 08:00 AM
Room: Ballroom
Description: 

An elevating seismicity rate is observed in Delaware Basin, western Texas within the past ~5 years (Skoumal et al., 2019). Meanwhile, InSAR observations reveal complex surface deformation up to centimeter-level over the oil production region, with increasing deformation rate during Nov. 2014 - Jan. 2019. While the seismic energy only accounts for a small fraction of the accumulated strain based on the surface deformation, possible candidate would be aseismic deformation associated with fluid injection and migration. In this study, we aim to obtain the stress drops for individual earthquakes to examine the spatial variation, which helps to shed light on the fault stress condition and underlying aseismic deformation across the region. Specifically, we start with the more complete catalog from template matching (Skoumal et al., 2019) and request the raw waveform data recorded by stations of network TX and SC with sampling rates of 100-200 samples/s. Then, we select earthquakes with magnitudes above 2.0 as candidate master events and search for nearby earthquakes within 2km as potential Empirical Green’s Function (EGF). During the study period from May 2017 to Jan 2019, we end up choosing ~400 candidate master events with M_L2.0-3.7. A spectral ratio method is further utilized to constrain the corner frequency of the master event. We will present our stress drop analysis and investigate whether the spatial variations of earthquake stress drop are indicators of the underlying aseismic processes.

Presenting Author: Dongdong Yao

Authors