# Investigation of hydraulic fracturing-induced seismicity in the Haynesville Shale

## TL;DR

This study investigates whether hydraulic fracturing in the Haynesville Shale causes earthquakes, finding three cases linked to the process.

## Contribution

The study identifies three new cases of hydraulic fracturing-induced seismicity in the Haynesville Shale using improved seismic detection methods.

## Key findings

- Three cases of hydraulic fracturing-induced seismicity were identified in the Haynesville Shale region.
- Seismic monitoring using template matching increased earthquake detections by over 200%.
- Geological factors like formation depth and salt layer absence may influence seismic activity.

## Abstract

The Haynesville Shale in eastern Texas and western Louisiana has been one of the most productive shale gas plays in the USA. It is notable for being significantly over-pressured, a factor which has often been associated with an increased likelihood of hydraulic fracturing-induced seismicity (HF-IS) elsewhere. However, to date, only one case of HF-IS has been identified in the Haynesville play. Seismic monitoring across the play is relatively sparse, so it is possible that the absence of reported cases represents an absence of monitoring rather than an absence of cases. This study represents an investigation of HF-IS across the Haynesville play, primarily using data from the TexNet seismic monitoring array, which was installed in 2017. We use template matching to increase the population of detected earthquakes, increasing the number of detections by over 200% compared to the catalogs available from regional monitoring agencies. The resulting events can be clustered into several discrete sequences. We use an induced seismicity assessment framework to evaluate whether each sequence was induced and, if so, what industrial activity represents the most likely cause (both hydraulic fracturing and wastewater disposal operations take place within the footprint of the Haynesville play). We find three notable cases of HF-IS, straddling the region between Nacogdoches, San Augustine and Shelby Counties. Having identified these sequences, we examine whether any geological conditions may influence the occurrence of HF-IS. We identify increased formation depth, increased pore pressure gradients, and the thinning or absence of the underlying Louann Salt, which may otherwise serve as a hydraulic barrier between the Haynesville Shale and the basement, as factors that may account for the varying prevalence of HF-IS across the play.

The online version contains supplementary material available at 10.1007/s10950-025-10296-x.