Supplemental material to "Probabilistic identification of seismicity triggered by oil and gas activities"

[RENAME FILE TO "X.ZIP" TO OPEN]

This is supplemental material to the Final Technical Report for the USGS Earthquake Hazards Program Grant #2022-0076 of G22AS00006 

Title: “Probabilistic identification of seismicity triggered by oil and gas activities and its effects on seismic hazard”PIs: Dr. Iason Grigoratos, Prof. Stefan Wiemer [SED @ ETH Zurich]

questions/comments: [e-mail] 

Abstract:

The present study employed an established semi-empirical earthquake recurrence relation to model the observed seismicity in Central and Eastern United States (CEUS) given the time-history of oil and gas activities. The model is founded on established physics-based principles that directly into account the external driving forces, i.e. the oil and gas activities, via the injection rates. Although the model is generic to be applicable in any region and covers both HF and wastewater disposal (SWD) cases, it matches well the earthquake time-history across various scales and regions. Besides hindcasting past seismicity rates, our main goal is to employ the model to distinguish the causal factors of induced seismicity across CEUS, including areas with overlapping oil and gas activities, something that has always been a challenging issue that is lacking a homogeneous response in the existing literature. The release of national maps identifying areas with induced seismicity, where the long-term USGS hazard models might deviate significantly from the near-term rates, would benefit the public, various stakeholders, insurance companies, and state-regulators.

To that end, we unified about 30 earthquake catalogs and collected HF data for all the CEUS states (west of W 117). Next, we examined cases of seismicity induced by HF in Oklahoma, the Raton basin, the Eagle Ford, the Fort Worth basin, and the Permian basin. We also collected data and analyzed the following regions in terms of a relationship between seismicity and SWD: Oklahoma, Kansas, the Raton basin, the Eagle Ford, the Fort Worth basin, the Midland basin and the Delaware basin.

We concluded that wastewater disposal is a main driver behind the elevated seismicity in the Delaware basin (both shallow and deep), the Midland basin (deep), southern New Mexico (deep), central Oklahoma (deep), and south and central Kansas (deep), with HF triggering significant levels of seismicity in the Delaware basin, the Eagle Ford, and in south and southwestern Oklahoma. Our conclusions were in very good agreement with previous studies. The present investigation identified for the first time clusters triggered by SWD in the Eagle Ford (both in the center of the basin and along the Mexico-TX border), as well as clusters triggered by HF in central and northern Oklahoma. Furthermore, we were able to link all the clusters of Culberson county and the enigmatic Irving-Dallas sequence to deep SWD. We were also able to link at a statistically significant level six events with magnitude 5 and above since 2010 within our basins to wastewater disposal operations. Finally, we highlight three events that require further research in terms of their triggering process: the 2015 Venus Mw 4.0 earthquake in the Fort Worth basin, the 2011 Trinidad Mw 5.3 earthquake in the Raton basin and the 2011 Prague Mw 5.7 earthquake in central Oklahoma.