(Click for larger image [53KB])


Collaborative USGS-NEES Earthquake Hazard Studies in the New Madrid Seismic zone and Puget Sound, WA

Principal Investigator: Robert Williams, US Geological Survey (USGS)

The overall goal of these experiments is to provide high-resolution images of the sediment structure and faults in the Arkansas portion of the New Madrid seismic zone and the Puget Sound region, Washington. These data will provide key constraints on earthquake hazard assessments in these large, at risk areas, and lead to improved earthquake ground motion simulations that earthquake engineers could use to assess potential losses. This collaboration promotes the basic goal of NEES "to engage and support earthquake risk-mitigation partners in experimental activities that improve the seismic design and performance of our infrastructure systems through the integration of people, ideas, and tools".

The proposed research consists of seismic reflection experiments to image the upper 1 km of the sedimentary basins underlying the New Madrid Seismic Zone, Arkansas, and the Olympia fault, Washington. Each seismic profile would be about 10-km in length using P-waves generated by the vibroseis truck Thumper. These studies are motivated by the need to better understand the sedimentary basin structure and detect faults that may be hidden under the recent alluvial cover in these seismically active areas. Both studies are motivated by the need to better understand the spatial and long-term temporal patterns of deformation, so that earthquake recurrence models that underlie hazard assessments may be put on sounder scientific footing. We suggest that this can be done while also addressing the need to better constrain how seismic waves propagate in the thick sediments of the Mississippi embayment and the Puget Sound area, key aspects of earthquake hazard assessments in these regions.