Active Tectonics

Earthquakes occur because of slow tectonic strain accumulation across a fault within a larger plate boundary zone. We  use InSAR and GPS to measure strain accumulation to better understand how fast faults are moving at depth, what is their seismic potential, what are the processes during earthquakes, and  how is deformationis distributed across a plate boundary zone.

Chaman Fault System

 Chaman Fault SystemThis fault system in Pakistan and Afghanistan, which forms the plate boundary between the Indian and Eurasian plates, features some of the world’s largest continental strike-slip faults. InSAR data and careful analysis of the uncertainties, shows that the Chaman Fault proper features a 340 km long creeping segment and accommodates only about one third of the plate boundary zone deformation [Fattahi & Amelung,2016]. The fastest moving fault is the Ghazaband Fault, posing a significant earthquake hazard to the city of Quetta.

In another study we have shown that moderate earthquakes along the Ghazaband Fault can be followed by significant afterslip [Fattahi et al., 2015].

2010 Haiti earthquake

2010 Haiti earthquakeThe M7.2 Haiti earthquake was a reminder of the seismic activity in the Carribbean. Our study using InSAR and GPS suggests that the earthquake occurred on a blind fault within the Haiti fault and thrust belt and not on the well-known Enriquillio-Plantain Garden strike-slip fault further south. Our study implies that the accumulated along this major strike-slip fault was not relieved. See our Nature Geoscience paper.

2008 Reno-Moghul earthquake swarm

2008 Reno-Moghul earthquake swarmA 2008 M4.7 earthquake swarm near Reno, Nevada, was one of the largest seismic events in the tectonically active Western Basin and Range in the past decades. The swarm caused only a few cm of ground displacement. The data showed that strike-slip occurred on a previously unknown NW-striking fault. This is an uncommon direction for tectonic activity in the normal-faulting dominated Basin and Range and suggest west-ward migration of Walker Lane-type right-lateral shear. See our GRL paper.

Basin and Range deformation

Basin and Range deformationWe have used the available ERS SAR archive to study active processes in the Basin and Range. We find that there is an area of subtle uplift (2-3 mm/yr) in the Pleasant Valley area, possibly uplift in the Ruby Valley area and that Valleys are actively tilting in the Central Basin and Range. The Pleasant Valley uplift is best explained by ongoing post-seismic deformation following a 1917 M7.6 earthquake. We are still working to find an explanation for the tilting valleys. Please e-mail Fernando Greene for a copy of the submitted paper.