Tectonic Reactivation of Oceanic Fracture Zones, Davie Ridge

Columbia University, New York NY

Investigators

Abstract

Plate boundaries are locations where two tectonic plates meet. New plate boundaries form by rifting an existing plate at places that are weak. This project will focus on the Davie Fracture Zone in the Mozambique Channel. The study will integrate several datasets to study how inherited oceanic structures control the development of incipient tectonic plate boundaries. Methods include machine learning approaches. The project will produce new maps of high seismic hazard zones. Other broader impacts include international collaborations and training of a graduate student. The project will test two hypotheses: Hypothesis 1: The kinematics of extensional reactivation of oceanic fracture zones are variable along-strike of the fracture zone, driven by inherited bends and offsets along the fracture zone. Hypothesis 2: The kinematics of reactivation is uniform along-strike of the fracture zone, facilitated by local stress field rotations that deviate from the regional stress field but act to maintain a fault reactivation style that is consistent along-strike. Here, inherited bends only influence the incipient rift geometry, but do not influence the rift kinematics. This study will use temporary and permanent seismic stations, including historical data in Madagascar, to develop an enhanced earthquake catalog, earthquake source mechanism solutions, and the contemporary stress field. In addition, the PIs will generate an updated neotectonic structure map of the entire reactivating oceanic fracture zone. The project will help evaluate hazards in the region, as fault reactivation offshore may trigger tsunamis. The newly developed earthquake catalog and active fault database for the Davie fracture zone will be invaluable for refining seismic hazard models. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.