Spatiotemporal Clustering and Migration of Seismicity in the Delaware Basin: Insights into the Causal Mechanisms of Induced Basement Earthquakes

Yijian Zhou, Krittanon Sirorattanakul, Zijun Fang, Jaewoo An, Jeff Nunn, & Jean-Philippe Avouac

Submitted September 7, 2025, SCEC Contribution #14754, 2025 SCEC Annual Meeting Poster #TBD

The Delaware basin, located in west Texas and southwest New Mexico, is one of the most productive shale basins in the U.S. since 2010. Induced seismicity surged after 2014, including 6 M > 5 since 2010, with the most recent one occurring in 2025/02. However, the causal mechanism is still under debate because of the various oil and gas operations taking place, including deep and shallow wastewater injection, oil production, and hydraulic fracturing. In this study, benefiting from an enhanced seismic catalog provided by Chevron, we perform spatiotemporal clustering and seismicity migration analysis to investigate the causal mechanism. We first applied a workflow designed to separate distinct spatial clusters of microearthquakes. It starts with running HDBSCAN algorithm with multiple sets of parameters, then merging the results and manually refining complex clusters, yielding 160 clusters with >100 events. Secondly, we quantify the temporal clustering patterns of each cluster using Fano Factor with 1-day bins. We found that larger clusters in the NW area tend to show bursts of day-long duration, which is a special feature to investigate in the future. Thirdly, we developed a set of criteria to automatically detect migration in the seismic clusters. This classification method involves measuring migration speed over consecutive 400-day windows along depth and 3D distance to the initial point. We utilize a quantile regressor algorithm for both 5% & 95% contours, representing migration forefront and backfront. A migration period is declared if one direction (depth or 3D distance) exhibits >1 m/day migration speed while the other dimension does not shrink faster than 1 m/day. Clusters in the NW area of Delaware basin show consistent down-dip migration over the years, while the other areas don’t show systematic migration. This migration feature correlates well with the wastewater injection history, as the NW area has an increasing injection rate over our study period. We find that most of the migrating clusters also exhibit a termination back front as expected from fluid diffusion triggering. Collectively, our seismicity clustering and migration analysis highlights the role of fluid diffusion in the triggering of earthquakes in the Delaware Basin.

Key Words
Seismicity migration, Delaware basin, Waste water disposal

Citation
Zhou, Y., Sirorattanakul, K., Fang, Z., An, J., Nunn, J., & Avouac, J. (2025, 09). Spatiotemporal Clustering and Migration of Seismicity in the Delaware Basin: Insights into the Causal Mechanisms of Induced Basement Earthquakes. Poster Presentation at 2025 SCEC Annual Meeting.

Related Projects & Working Groups
Seismology