T002-0001
Injection-Induced earthquake clusters in Raton Basin, New Mexico & Colorado
Monday, 7 December 2020
Poster
Ruijia Wang, University of New Mexico, Earth & Planetary Sciences, Albuquerque, United States, Brandon Schmandt, University of New Mexico, Department of Earth & Planetary Sciences, Albuquerque, NM, United States, Wenyuan Fan, Scripps Institution of Oceanography, UC San Diego, La Jolla, CA, United States, Margaret Elizabeth Glasgow, University of New Mexico Main Campus, Albuquerque, NM, United States and Eric Kiser, University of Arizona, Department of Geosciences, Tucson, AZ, United States
Abstract:
Waste-water injection induced seismicity has been active in the Raton Basin for the past two decades, including several M>4.0 normal-faulting earthquakes. To characterize the injection-induced fault reactivation processes, we utilize the state-of-the-art techniques to automatically detect and locate recent seismicity. We apply a machine-learning based phase picker (PhaseNet) to two datasets: 1) 8 broadband stations available since 2016 with an averaged spacing of ~30 km and 2) 96 high-frequency nodal instruments that were deployed for one month in the southern section of the basin in the summer of 2018, and detect millions of P and S phase arrivals. We obtain catalogs that include ~ 30,000 events down to M0 using the broadband stations for the 3.5-year period and ~10,000 events down to M-2 using the nodal array data during the one-month period, which cluster into multiple fault systems ranging from N-S normal to oblique dip-slip regimes. To further understand the complex faulting regimes and the rupture processes of induced earthquakes, we investigate M3 earthquake finite fault attributes using the second moments method, which uses the apparent source time functions to determine the rupture dimensions, duration and speed. For example, we obtain robust results for the June 10, 2018 (M3) event, suggesting the N-S dip-slip as the true fault orientation.
Our statistical analysis does not differentiate the studied clusters from tectonic earthquake sequences in space/time/magnitude domains (i.e., dominated by earthquake interactions). We hypothesize that the induced-earthquake clustering characteristics are influenced by the injection rates, with higher injection rates leading to reduced clustering. The injection rates in the Raton Basin have been much lower than in other areas where diminished earthquake clustering has been observed, so this may explain why earthquake interactions continue to dominate in the Raton Basin. Overall, detailed fault structures and earthquake cycle statistics inferred from a high-resolution earthquake catalog can serve as observational base for physics-based mechanical modeling and hazard mitigation in Raton Basin.
