Induced & triggered seismicity
Since about 2009, the rate of earthquakes in the central and eastern U.S. has dramatically increased, mostly due to wastewater injection in Oklahoma, but also due to various causes in Texas and other states. To understand the mechanical setting of these earthquakes, and ways in which operators can reduce the probability of triggering future events, I am compiling stress data and developing tools to mitigate the induced seismic hazard in Texas, New Mexico, and the surrounding region. To this end, Mark Zoback and I recently published two papers that together contribute about 300 new principal stress magnitudes, together with a comprehensive map of the faulting regime, across Texas, New Mexico, and surrounding areas.
Principal stress orientations and magnitudes are fundamental for understanding the causes of past earthquakes and for identifying faults of concern for future seismicity. Our first paper presented the results of the Stress Map of Texas and examines recent, potentially triggered earthquakes in the context of the mapped stress field. A second paper added considerably more data on the state of stress in the Permian Basin of West Texas and southeast New Mexico, which is currently the most important oil-producing region in the United States. In this study, we estimated the slip potential of mapped faults using the FSP tool and compared sensitive faults with locations of known seismicity (see figure), emphasizing the need for more detailed studies of the region’s geology. A third study paired new stress data in the Fort Worth Basin, northeast Texas, with a detailed new 3D map of faults built by scientists at UT Austin and Southern Methodist University. We found that most faults in the area—including many under Dallas and Fort Worth—have the same slip potential as those that have already produced earthquakes.