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February 4 @ 4:00 pm - 5:00 pm CST

Current Research in EEPS: Dr. Lars Hansen, University of Minnesota

From mega-annum to microseconds: the role of crystal dislocations in the dynamics of the solid earth

Large-scale geodynamic processes in the solid Earth often depend intimately on small-scale defects within the constituent minerals. These processes span a wide range of time scales and include convection in the upper mantle, flexure of the lithosphere, glacial isostatic adjustment, postseismic creep, and frictional sliding on faults during earthquakes. Here I describe the influence of dislocations, a particular type of crystal defect, on this range of processes within upper-mantle rocks. The role of dislocations across these timescales is elucidated by a series of laboratory experiments including synchrotron-based experiments to measure yield stress and strain hardening, high-temperature uniaxial tests to investigate anelasticity, and dynamic indentation using ball-drop experiments to assess mineral strength at extreme strain rates. These different experimental approaches are linked through the dynamics of dislocations. The resulting model of dislocation-based deformation resolves conflicts among previous geophysical observations and provides a series of new predictions about the mechanical properties of rocks at both slow and fast timescales not typically accessible in the laboratory.

Details

Date:
February 4
Time:
4:00 pm - 5:00 pm CST
Event Categories:
,

Venue

Dept. Earth Science, Rice University, 6100 Main Street
Houston, TX 77005 United States
Phone:
7133484880

Details

Date:
February 4
Time:
4:00 pm - 5:00 pm CST
Event Categories:
,

Venue

Dept. Earth Science, Rice University, 6100 Main Street
Houston, TX 77005 United States
Phone:
7133484880

For outside visitors, the best way to get to our department is to come in on Rice Blvd and turn left into entrance 20 (intersection of Rice and Kent St.). At the stop sign, you will see a visitor parking lot on your right.  From there, walk east to the department.  The google map below shows exactly where our building is.