Speaker: Dr. Samer Naif (Georgia Institute of Technology)

The distribution of fluids in Earth’s interior is a key variable in a variety of regional tectonic and magmatic processes. In this presentation I will review induction-based electromagnetic methods and their ability to image fluids, with a focus on applications to fault coupling and seismicity behavior at subduction zone forearcs. Results from surveys at the Hikurangi, Alaska-Aleutian, and Central American margins show how fluids, in conjunction with other relevant physical properties in both the downgoing and overriding plates, can influence seismicity in myriad ways. At Hikurangi, the degree of structural heterogeneity and the roughness of the subducting seafloor correlate with plate coupling. At the Shumagin segment of Alaska-Aleutians where plate coupling is weak, the plate interface lacks fluids updip yet is fluid-rich downdip where the 2020 Simeonof earthquake ruptured, suggesting that fluids alone are not responsible for the patterns of coupling yet may enable dynamic rupture propagation in weakly coupled faults. These studies demonstrate that amphibious geophysical imaging on a regional scale is necessary to elucidate how fluids may be controlling seismicity at a particular setting.