Physical process of earthquake nucleation from extremely shallow seismic events in Southeastern U.S.

Zhigang Peng, Georgia Institute of Technology

Earthquakes are not frequent in the Southeastern United States (SEUS), but they do occur in areas with long-term seismic activity and in new regions with no clear seismic history. Most of these earthquakes have relatively small magnitudes (less than 1) and are therefore not well recorded by the current seismic network. Some are extremely shallow, with hypocenters less than a few kilometers deep. In this talk, I will provide an update on our recent efforts to study shallow microearthquakes in several regions of the SEUS using dense nodal seismic networks and advanced processing techniques such as machine learning and template matching. This includes the 2020 magnitude 5.2 Sparta earthquake sequence in North Carolina, the Elgin-Lugoff earthquake swarm in South Carolina that began in December 2021, and the rock exfoliation event at Arabia Mountain in Georgia on July 17, 2023. Studying these extremely shallow events may offer new insights into the physical processes of earthquake nucleation.