Abstract During the past decade, Texas has seen an increase in earthquakes linked to oil and gas operations. Although typically moderate in magnitude, their increasing frequency highlights the need to better understand induced seismicity. Accurate earthquake depth estimation is essential for understanding the physical mechanisms of induced seismicity but remains challenging in regions like the Culberson–Mentone earthquake zone (CMEZ) in the Delaware basin (DB), where earthquake depths are sparse and between 6 and 10 km below sea level. The challenges in this region include limited velocity models and complex and laterally heterogeneous geology. We introduce the S-P high-resolution catalog for CMEZ, refining TexNet depths using a two-step approach: S-P time differences and a local velocity model derived from sonic logs for events close to stations, and a relative relocation method for the remaining events. The results show consistent depths, revealing a deepening trend from west to east tied to the basement structure. Furthermore, the results suggest that deep seismicity in the CMEZ is controlled primarily by pore pressure diffusion from deep wastewater disposal injection zones, and it could be further influenced by earthquake-to-earthquake interactions that may facilitate stress transfer and fault reactivation at greater depths. These findings underscore the importance of dense seismic networks, accurate velocity models, and S-P times for accurate depth refinement, and highlight how continuous depth monitoring can improve understanding of induced seismicity and inform seismic hazard assessments in the DB.
Castillo et al. (Fri,) studied this question.