Relocating the Eagle Ford Earthquake Catalog for TexNet with a Regional 1D Velocity Model

Abstract Seismicity in the Eagle Ford Shale (EFS) of south-central Texas has increased over the past decade, largely because of intensified oil and gas activities. Since 2017, the Texas Seismological Network (TexNet) has improved monitoring in this region, increasing cataloged earthquakes from 33 events with M ≥ 2.3 (1982–2017) to 3882 events with M ≥ 0.4 (2017–2026). However, routine TexNet locations in southern Texas relied on the global IASP91 1D velocity model, which cannot best constrain the focal depths because of the overly simplified crustal structure that ignores local geologic features. Here, we present a relocated EFS earthquake catalog for TexNet operations using a regional 1D velocity model (EF1D). Compared with the original IASP91-based catalog, travel-time residuals decreased, and hypocenters tightened into northeast–southwest lineations that coincide with mapped normal faults. Most events were relocated to ∼6–9 km depth and near the basin–basement interface, indicating predominantly basement-rooted seismogenic faults. We relocated all 2461 EFS events in the TexNet catalog from 2017 through May 2025 with EF1D, and events detected after July 2025 in southern Texas are now routinely reported with this model. The relocated catalog and metadata are publicly available through the TexNet Earthquake Catalog and the U.S. Geological Survey ComCat and International Federation of Digital Seismograph Networks webservices, superseding earlier EFS solutions and improving the basis for induced seismicity and hazard studies in southern Texas.