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Characteristics of a Complex Rupture Zone System Associated With the m5.4 Coalson (West Texas) Earthquake

Description: 

Seismicity in the Delaware Basin (West Texas) has greatly increased from 46 earthquake of M≥2.5 in 2017 to 692 events in 2022. This area has the highest rate of seismicity in the State of Texas, with 37 M≥4.0 events since 2017, and the highest magnitude earthquake (M5.4, 2022-11-16, Coalson Earthquake) since 1995 in Texas. The Coalson seismicity is 10km South of the M4.9, 2020-03-26, Mentone earthquake sequence and defines a complex rupture zone with 12 M≥4.0 events that occurred from September 18^th, 2021 to November 24^th, 2022 (all information as reported by the TexNet web catalog last accessed on January 10^th, 2023; https://catalog.texnet.beg.utexas.edu/). Based on the USGS “Did You Feel it” (DYFI) reports, the M5.4 event was felt throughout most of the State of Texas and Southeast New Mexico, including the large urban areas of San Antonio, Houston and Dallas.

We have relocated the seismicity in the Coalson area using an initial, local 1D Earth Model and two high-precision relocation methodologies: the extended, arrival-time method NLL-SSST-coherence and the GrowClust double-difference procedure. We also use full waveform Moment Tensor Inversion (MTI) to determine the focal mechanisms of the highest magnitude earthquakes in the area. Combining the MTI results with the spatio-temporal seismicity distribution we identify a complex system of basement rooted faults that extend upwards to the deep salt water injection zone. These active rupture zones follow E-W and SE-NW strike directions, with vertical dip-slip and low-angle normal faults, respectively.

Session: Advances in Characterizing Seismic Hazard and Forecasting Risk in Hydrocarbon Systems

Type: Oral

Date: 4/18/2023

Presentation Time: 02:45 PM (local time)

Presenting Author: Alexandros Savvaidis

Student Presenter: No

Invited Presentation: 

Authors