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Raton Basin induced seismicity is hosted by networks of short basement faults and mimics tectonic earthquake statistics
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  • Margaret Elizabeth Glasgow,
  • Brandon Schmandt,
  • Ruijia Wang,
  • Miao Zhang,
  • Susan L. Bilek,
  • Eric Kiser
Margaret Elizabeth Glasgow
University of New Mexico

Corresponding Author:[email protected]

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Brandon Schmandt
University of New Mexico
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Ruijia Wang
University of New Mexico
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Miao Zhang
Dalhousie University
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Susan L. Bilek
New Mexico Tech
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Eric Kiser
University of Arizona
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Abstract

The Raton Basin is known as an area of injection induced seismicity for the past two decades, but the reactivated fault zone structures and spatiotemporal response of seismicity to evolving injection have been poorly constrained in the past due to scarce public monitoring. Application of a machine-learning phase picker to four years of continuous data from a local array enables the detection and location of ~38,000 earthquakes. The events between 2016-2020 are ~2.5-6 km below sea level and range from ML<-1 to 4.2. Most earthquakes occur within previously identified ~N-S zones of seismicity, however our new catalog illuminates these zones are composed of many short faults with variable orientations. The two most active zones, the Vermejo Park and Tercio, are potentially linked by small intermediate faults. In total, we find ~60 short (<3 km) basement faults with strikes from WNW to slightly east of N. Faulting mechanisms are predominantly normal but some variability, including reverse dip-slip and oblique-slip, is observed. The Trinidad fault zone that hosted the 2011 Mw 5.3 earthquake is quiescent during 2016-2020, likely in response to decreased wastewater injection after 2012 and the shut-in of two nearby wells in 2015. Unlike some induced seismicity regions with higher injection rates, Raton Basin frequency-magnitude and spatiotemporal statistics are not distinguishable from tectonic seismicity. The similarity suggests that induced earthquakes in the Raton Basin are dominantly releasing tectonic stress.
Nov 2021Published in Journal of Geophysical Research: Solid Earth volume 126 issue 11. 10.1029/2021JB022839