Ground Motion Studies
The Earthquake Effects project collects field data from seismic imaging, ground motion, and ground failure, and processes this information to yield better seismic hazard assessments and products. The key to better ground motion predictions lies in more accurate specification of the 3D velocity structure. We require accurate information on the shallow (top 100m) shear-wave velocity structure, as well as the thickness of Quaternary sediments, the depth to basement, and the velocities within these units. To obtain this information this project conducts both shallow and mid-level depth (1-2km) imaging experiments for P- and S-wave velocity, fault delineation, and sedimentary basin geometry. The project also collects ground motion data from local and regional earthquakes to obtain information on velocity structure and to study focusing of seismic waves and calculate site response. All these lines of investigation allow for the production of better urban seismic hazard maps. These studies are also used in conjunction with theoretical work on seismic sources to produce time histories of ground motion for scenario earthquakes. This work is facilitated by the development of better modeling and imaging software. Estimates of ground shaking from the above studies feed into the development of more accurate models of coseismic landslide behavior to reduce loss from ground failures.
Photo: During an earthquake in Pymatuning, PA in 1998, a Foucault's pendulum acting as a seismoscope scribed this incredible work of earthquake art.