Thursday, October 29, 2015

UW Researchers to Publish Geophysics Study in Science

 We at EPSCoR were glad to hear that UW geoscientists will publish research in Science this October 30th.  (Just in time for Halloween!) 

James St. Clair, a UW doctoral student, is lead author of the paper, titled “Geophysical Imaging Reveals Topographic Stress Control of Bedrock Weathering.”  Steve Holbrook, a professor of geology and geophysics; Cliff Riebe, an associate professor of geology and geophysics; and Brad Carr, a research scientist in geology and geophysics, are co-authors of the paper. 
James St. Clair

Geophysical imaging of the subsurface was conducted by UW’s Center for Environmental Hydrology and Geophysics (WyCEHG).  Scientists at MIT and the University of Hawaii contributed numerical models of the stress distribution in the subsurface. 

Geophysical imaging uses different tools to create a detailed picture of the composition, shape, and density of subsurface rock strata.  Scientists can use a variety of technologies to take measurements, and then combine those measurements into maps of the mountain surface and interior.  The team performed seismic refraction and electrical resistivity surveys to look at the depth to bedrock at three mountain sites.  These three sites were chosen because they showed variant, or different, regimes of mountain topography and tectonic stress. 

Researchers used geophysical surveys to estimate the volume of open pore space in the subsurface.  This is an indication of how much water the subsurface can hold.  Computer models showing the state of stress at those sites showed striking correlation with open pore space measurements.  This means that scientists may be able to use measurements of the stress in the earth’s crust to see where water can be stored. Stress in the earth’s crust creates fractures in the earth’s subsurface, and those fractures create space to hold water.      

 “We found a remarkable agreement between the predictions of those stress models and the images of the porosity in the subsurface with geophysics at a large scale, at the landscape scale,” Holbrook says.  “It’s the first time anyone’s really looked at this at the landscape scale.” 

St. Clair is excited to be publishing research in Science, a prestigious scientific journal.  He feels lucky to work with such a talented, experienced group of scientists.  He believes that these results may be extremely useful to hydrologists, geomorphologists, and geophysicists. 

Steve Holbrook adds that there is still a lot of work to be done to test this model in different environments.  However, he says, “Now we have a theoretical framework to guide that work, as well as unique geophysical data to suggest that the hypothesis has merit.” 

Written by Jess White

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