Speaker: Dr. Steve Roecker, Rensselaer Polytechnic Institute
The abundance of seismic activity, including frequent megathrust earthquakes, along the Andean margin of South America makes it an attractive venue for investigating the interplay between these large events and a variety of phenomena such as mantle hydration, subduction erosion, and wedge tectonics. In this talk I will review recent and ongoing research involving the application of seismic tomography to illuminate how processes in the upper (South American) plate may be influencing the occurrence of these events. I will discuss results from two regions: the Northern Chile Seismic Gap, which last ruptured in a Mw8.9 event in 1877 and the Illapel region of Central Chile which recently (2015) experienced an Mw8.3 event. Among the principle results from the tomographic images we have generated thus far include the discovery of strong variations in mantle hydration in the Northern Chile region and evidence for subduction erosion causing normal faulting in the Andean coastal wedge of central Chile.