Insights Into Spatiotemporal Evolution of Induced Earthquakes in the Southern Delaware Basin Using Calibrated Relocations From the TexNet Catalog (2017–2022)

Abstract

This study presents a comprehensive analysis of induced seismicity (2017–2022) and InSAR-derived surface deformation in the southern Delaware basin. The relocated catalog features improved 3-D locations for 5,453 events from the Texas Seismological Network through nested inversions, rigorous data calibration, and additional S-P phase-time differences for seismic stations within 10 km distance. Time and space variations in absolute and relative earthquake location errors reflect the complicated history of station coverage in the region and the importance of having close-in stations to resolve shallow-depth earthquakes. The mean seismogenic depth of the new catalog is 1.5 km below mean-sea-level, consistent with reactivation of shallow normal faults within the Delaware Mountain Group (DMG) and the Bone Spring Formation driven by shallow saltwater disposal. Linearly segmented, short-wavelength subsidence patterns align with seismically active lineaments interpreted as shallow normal faults, while long-wavelength production-related subsidence signals are radially symmetric and aseismic where they do not coincide with injection hotspots and faults. The revised M2+ catalog maps a reduction in the number of events in the northern and central parts as well as an increase in the number of events in the southeast since 2020, and this signal precedes measurable surface deformation. We posit that this relationship reflects efficient pressure diffusion along permeable northwest-southeast faults and/or the thickening of porous sandstone in the DMG prone to seismic slip. The spatial and temporal patterns of seismicity, uplift-subsidence, and basin-wide fluid extraction and disposal indicate inhomogeneous and time-variant seismic and aseismic deformation under an anthropogenically modulated stress regime.