Mechanics of earthquakes
Rheology of the lithosphere and fault zones
My research focuses on the mechanics of faulting within regions of diffuse continental deformation. I am particularly interested in understanding the distribution of frictional properties on fault zones and the strength of continental faults in terms of the stresses they can support through the elastic portion of the lithosphere.
My current work uses a combination of observational techniques from geomorphology, space-borne satellite geodesy (InSAR, GPS), seismology and structural geology to measure ground deformation during and after earthquakes. These observations can then be used to constrain physical models of stick-slip and creeping motion along fault surfaces to determine their frictional properties and strength.
It is important to address these questions as the frictional properties of faults govern the style of slip that can occur along them, and the potential size of earthquakes.
Locking on Intra-continental Faults:
Following the 2003 Mw 6.6 Bam earthquake in SE Iran, we measured the post-seismic ground deformation using radar satellites (InSAR). We used these measurements, in conjunction with numerical models of fault creep in response to co-seismic stress changes, to show that the data are consistent with only a small area of the available fault surface creeping in response to loading due to the earthquake.
This provides the first indirect evidence for locking along an intra-continental fault through the use of post-seismic deformation. Faults that remain predominantly locked are likely to release the majority of slip in earthquakes, hence can be considered to pose a greater seismic hazard relative to those that creep extensively (e.g., Longitudinal Valley Fault, Parkfield section of the San Andreas).
earthquake geology ; Geophysics ; Geodesy ; Seismology
Sam Wimpenny, Alex Copley, Tom Ingleby; Fault Mechanics and Post-seismic Deformation at Bam, SE Iran. Geophys J Int 2017 ggx065. https://doi.org/10.1093/gji/ggx065