Collaborative Research: Subduction, Collision, and Mountain Building, a Broadband Seismic Experiment Across the Alaska Range (BEAAR)

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9725168Christensen This research involves a deployment of portable PASSCAL seismographs across the Alaska Range near Mount McKinley to study the active tectonics and generation process of large mountains at subduction zones. Two broad types of processes are usually proposed: horizontal compression, which results in crustal thickening and support of mountains by Moho deflections, and dynamic uplift mechanisms, which heat the lithosphere or elevate it by subduction-induced flow. The PASSCAL seismic line of stations follows a corridor that typifies mountain building over a subducting slab with North America's highest topography directly over the 100 km depth contour of the slab where arc volcanism might be expected. Analysis efforts will focus on receiver functions, attenuation and travel time studies, and shear-wave splitting. Results will be integrated with topography and gravity observations of mass distributions, in order to examine whether these are sufficient to isostatically balance topography. These balances will show for the first time the forces that elevate topography here and generate earthquake activity. This research is a component of the National Earthquake Hazard Reduction Program.***