Crustal stress & geodynamics

New stress map of the Permian Basin. Black lines represent measured directions of maximum horizontal stress. The colored background represents whether the Earth’s crust is extensional or compressional. Blue areas to the west indicate that normal (extensional) faults are potentially active, yellow (mostly out of view to the northeast) represents strike-slip faulting (more compressional), and green means that both normal and strike-slip faults are potentially active. Earthquake locations are shown as colored dots and reported by the U.S. Geological Survey National Earthquake Information Center, TexNet Seismological Network, and Gan and Frohlich (2013). In recent years, several new clusters of earthquakes (red dots) have occurred in the southern Delaware Basin, near the towns of Pecos and Fort Stockton, and another cluster has occurred near Midland. In contrast, older events (orange dots) are concentrated on the Central Basin Platform.

New stress map of the Permian Basin. Black lines represent measured directions of maximum horizontal stress. The colored background represents whether the Earth’s crust is extensional or compressional. Blue areas to the west indicate that normal (extensional) faults are potentially active, yellow (mostly out of view to the northeast) represents strike-slip faulting (more compressional), and green means that both normal and strike-slip faults are potentially active. Earthquake locations are shown as colored dots and reported by the U.S. Geological Survey National Earthquake Information Center, TexNet Seismological Network, and Gan and Frohlich (2013). In recent years, several new clusters of earthquakes (red dots) have occurred in the southern Delaware Basin, near the towns of Pecos and Fort Stockton, and another cluster has occurred near Midland. In contrast, older events (orange dots) are concentrated on the Central Basin Platform.

As part of my work at the Stanford Stress & Crustal Mechanics Group and the Stanford Center for Induced & Triggered Seismicity, I am working with Mark D. Zoback to build a high spatial resolution stress map of the south-central USA. We have compiled some 300 new high-quality stress orientations through partnerships with industry, and we are also mapping faulting regime (relative principal stress magnitudes). Our new data show a surprisingly variable stress field across the region, which provides an opportunity to understand the contribution of tectonic and local, geodynamic factors to stress perturbations.

In 2016, we published a paper in Geophysical Research Letters presenting our first 200 stress orientations. The results show a surprisingly variable but coherent stress field across the area. In 2018, we added some 100 more stress orientations in the prolific Permian Basin of west Texas and southeast New Mexico. Our stress map continues to grow, and we are currently working to understand the intriguing variations that we observe across the south-central USA.