Central and Eastern U.S. and Puerto Rico Geology

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Causative faults for Central and Eastern U.S. (CEUS) earthquakes are difficult to pinpoint because strain rates are low and earthquakes are rarely associated with clear young surface faulting.  Very few fault systems in the CEUS have long-term paleoseismic records compared to the western U.S. Low rates of seismicity across much of the region and infrequent damaging earthquakes create large uncertainty in the seismic hazard. Our goal is to conduct targeted geologic, geomorphic, stratigraphic, and remote sensing research in the CEUS to obtain paleoseismic data to reduce hazard uncertainties.

Current areas of focus in the CEUS include the Eastern Tennessee Seismic Zone, and Charleston, South Carolina. In contrast to the continental part of the CEUS, Puerto Rico is an active plate margin above a subduction zone. As such, it has far more earthquake activity than the continental CEUS and has the potential for large subduction-zone earthquakes and associated tsunamis. In Puerto Rico, the objective is to identify and characterize active faults in the region, as well as examine the ground motions that occur during earthquakes. Such studies include both on-land fault systems and offshore faults such as those associated with the subduction zone.

The research methods used in this project vary widely, but all have the goal of better understanding the distribution of active faults, the earthquake history of the CEUS and Puerto Rico, ground motions that may result from these earthquakes, and the underlying causes of seismicity within this stable continental plate.

Our overarching approach is to use paleoseismic, geomorphic, stratigraphic, and remote sensing techniques to extend the geologic record of faulting back in time through targeted studies.