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 central and eastern USA. We have compiled >400 new orientations of the maximum horizontal compression (SHmax) as well as a map of the faulting regime (relative principal stress magnitudes). Our new data show a surprisingly variable stress field across parts of the region—and broadly consistent patterns in others—which provides an opportunity to understand the contribution of tectonic and local, geodynamic factors to the stress field.

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.