This project uses data from permanent and temporary seismic observatories along the Pacific coast to probe the structure and texture of the crust and the upper mantle. We are especially interested in the properties of the rocks lining the contact (aka megathrust) between the subducting Juna de Fuca and overriding North American plates. The likelihood of large earthquakes on the megathrust depends on the properties of these rocks.

Initial study was performed at Corvallis by Park and colleagues. It suggested large fraction of serpentinite within the megathrust.

Our project follows up on this study, and we see evidence for serpentinized rock along ~40 km depth contour of the megathrust.

A cartoon at right shows contours of the megathrust in KM and locations we have studied, with sticks at some sites showing that we have detected systematic texture close to plate contact. Green sticks show sites where we think serpentinite is abundant. A long detailed paper was published in G3

Analysis of all Transportable Array data from the Pacific Northwest has been carried out. Results were presented at the 2009 Earthscope workshop and 2009 Fall AGU meeting.

A summary of all data processed using receiver function analysis methodology is here.