IGPP is pleased to invite you to join its Virtual Seminar Series presentation featuring Weisen Shen from Stony Brook University's Department of Geosciences. Dr. Shen's talk, "Crustal composition and strength: a revisit to the intermountain west seismic belt" will be available via Zoom on Tuesday, May 26, starting at 12:30pm. Zoom registration is available through here: https://ucsd.zoom.us/meeting/register/tJ0lcO-vqzktH9YHSdgV7cjRq36HyJzhapXA
Tuesday, May 26, 2020
Time: 12:30 pm, Pacific Time
Note: This meeting will be recorded.
Abstract: The Intermountain Seismic Belt (ISB), extending from Montana through Idaho, Wyoming, Utah, and into southern Nevada, represents a major intraplate seismic zone in the continental US. This seismically active boundary has been interpreted as a subplate boundary between the tectonically active W. US with the more stable cratonic core of North America. In this talk, I will revisit the seismic structure of this region and argue that the crust in the IBS is particularly weakened by its chemical composition being felsic. Particularly, I will show that by combining different seismic observations relatively accurate quantification to the chemical composition of the crust can be made, and in addition, can be further translated into the strength of the crust. Based on this approach, we draw the map of the crustal strength across the N.W. US with the USArray data and show that the crust of ISB is perhaps chemically weakened by more than 50% relative to its neighboring regions. This result, albeit caveats in assumptions, provides an alternative mechanism for intraplate seismicity in general.