The TexNet-CISR collaboration and steps toward understanding induced seismicity in Texas

Abstract

Diverse seismicity-prone geologic systems are located in Texas, USA. These systems include areas of tectonically natural earthquakes and areas with induced seismicity stemming from multiple factors. Some systems are geologically and operationally simple, such as the Fort Worth Basin, where multiple lines of peer-reviewed evidence indicate that earthquakes have been induced by injection of oil-field wastewater above the geologic basement, and the Eagle Ford region, where earthquakes have been induced principally by hydraulic fracturing activities. Other systems are far more complex, such as the Texas Panhandle, where natural seismicity and induced seismicity coexist, and the Delaware Basin, where wastewater disposal both above and below shale targets and hydraulic fracturing coexist with induced seismic events. Although cases of induced seismicity were documented in Texas as early as the 1980s, the public's attention and formal regulatory actions occurred after substantial increases in seismicity were observed proximal to unconventional hydrocarbon reservoir development in the Dallas. Fort Worth metropolitan area. These actions, intended to mitigate induced seismicity, included creation of the Texasfunded TexNet Earthquake Monitoring Program in 2015 and the formation of the industry-sponsored Center for Integrated Seismicity Research in 2016, implementing policy changes by the Railroad Commission of Texas, and altering field activities by the petroleum industry. A public-private partnership was established in Texas for monitoring earthquakes, conducting research on causation and evolving risk, and developing approaches for mitigation. This partnership between stakeholders represents a major concerted effort to address the evolving environmental hazards of induced seismicity. Even with these actions, however, the total number of earthquakes with ML ≥2.0 cataloged in Texas reached a record high of 2601 in 2022, representing more than double the number of earthquakes that occurred in 2020 and more than eight times the number that occurred in 2017. This chapter provides a recent history of seismicity in specific areas of Texas and the monitoring, research, and regulatory actions taken to mitigate induced seismicity.