User Profile: Rowena Lohman
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Research interests: Earthquake physics, inverse theory, satellite remote sensing, finite element modeling, ground displacements from a variety anthropogenic and natural causes, and the tectonics of southern California, Louisiana, the Cascadia subduction zone, and Iran. Her teaching interests focus on global geophysics, seismology, earthquake record reading, remote sensing, and active tectonics.
Lohman received a NASA New Investigator Program grant in 2011 to study subsiding deltas and sea level rise worldwide using space-based geodetic observations.
Current research focus: Global research related to fault zone behavior during and between earthquakes. Her primary area of interest involves the observation of fault behaviors that lie outside the standard ‘stick-slip’ model, where faults creep transiently in response to external stress changes. Lohman’s research aims to improve our understanding of the constitutive laws governing stress release along fault zones, as well as the stress within the subsurface. In the future, she hopes to incorporate recent advances by researchers working on the contribution from tides and the hydrologic cycle into her models of fault zone behavior and stress histories.
Data products and tools used:
- Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Digital Elevation Map (DEM) and Global Digital Elevation Map (GDEM) with variable resolutions. Data are available through the NASA Land Processes Distributed Active Archive Center (LP DAAC) (https://lpdaac.usgs.gov) or via NASA Earthdata Search (http://search.earthdata.nasa.gov)
- Synthetic Aperature Radar (SAR) imagery (primarily Level 0 and 1). Data are distributed by the NASA Alaska Satellite Facility (ASF) DAAC (http://asf.alaska.edu)
- Shuttle Radar Topography Mission (SRTM) DEMs, 30 and 90 meter. Available through the NASA LP DAAC (https://lpdaac.usgs.gov) or via the Global Data Explorer (http://gdex.cr.usgs.gov/gdex)
- Landsat imagery, Level 1 with variable temporal and spatial resolutions. Available through the Earth Explorer (http://earthexplorer.usgs.gov) and the Global Visualization Viewer (GloVis) (http://glovis.usgs.gov)
Research findings: “I have focused on small, shallow sources of deformation, including a M3.2 earthquake that occurred at ~700 meters depth in response to a local quarry blast in Chicago and a weeks-long shallow (<2 km) slip episode in a geothermal area in southern California,” notes Lohman. “Both are areas where the depth range and thermal gradients are such that earthquakes should not nucleate; rather, stable sliding should dominate (i.e., they are ‘velocity strengthening’). Only in the case of sudden stress changes or, potentially, material heterogeneities, should an earthquake be able to occur.”
Last Updated: Apr 25, 2019 at 2:02 PM EDT