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Date: 4/21/2021

Session Time: 2:00 PM to 3:15 PM Pacific

Advances in Upper Crustal Geophysical Characterization

The upper crust plays a critical societal role, from access to clean water to the production of energy to the impact of geologic hazards. It is also our window into the layers below; geophysical variability in the near surface can map into deeper structure if not properly considered. With respect to seismic hazards and earthquake ground motions, variability in near surface geophysical properties can lead to an overall amplification or deamplification of strong ground motions, large lateral variability in site response, as well as resonance at specific ground shaking frequencies. With respect to groundwater, characterizing soil porosity, regolith development and fracture permeability all lead to better estimates of storage potential and groundwater flow rates. Geophysical characterization of the near surface is therefore critical to being able to address these issues. A vast number of methods exists with which to characterize the subsurface from direct methods that measure rock density and seismic velocity in-situ to indirect methods where seismic wave travel times, gravity, resistivity and other parameters are measured at the Earth’s surface, and subsurface properties are inferred. We seek contributions that include direct and indirect field observations, laboratory experiments and geophysical theory that links observation and expectation to studies that explore the impact of competing assumptions.

Conveners

Oliver S. Boyd, U.S. Geological Survey (olboyd@usgs.gov)
William J. Stephenson, U.S. Geological Survey (wstephens@usgs.gov)
Lee M. Liberty, Boise State University (lliberty@boisestate.edu)

Oral Presentations