Seismo Lab Seminar

Oceanic transform faults (OTFs) are a fundamental piece of the plate tectonics puzzle as they connect the global system of mid-ocean ridges. Even so, there are many questions we have yet to answer regarding these seafloor strike-slip systems, which will have implications for our handling of earthquake hazards on land. One perplexing phenomenon that has been noticed on several OTFs is their segmentation into rupture patches, which nucleate large earthquakes, and barrier zones, which host tiny earthquakes but seem to halt larger slip. The Gofar OTF in the equatorial Pacific presents a well-studied, albeit poorly understood, example of this. In an effort to better explain the underlying cause of Gofar's barrier zone, we collected controlled-source electromagnetic data along three profiles that crossed the fault. Electromagnetic data provide information on the electrical resistivity of the subsurface, and they are very sensitive to conductive fluids, like magma and seawater, trapped in seafloor rocks. I will present the surprising results that have come from modeling these data and discuss how the results might shape our growing understanding of barrier zones and OTFs. I hope to convince you that OTFs are not such simple plate boundaries after all!