This grant will fund urgently needed support through the SGER program to cover the critical costs for field measurements of the large (M=7.5) Costa Rica earthquake of April 22, 1991. Prior to the main shock, the principal investigator installed a portable network of seismometers centered on the western coast of Costa Rica in anticipation of an earthquake there. These portable instruments augmented the joint Costa Rica/UC Santa Cruz permanent seismometer net installed in 1984. The April 22 event occurred just outside of the net on the eastern coast but valuable strong motion data were obtained. Additional portable stations will be deployed to surround the aftershock region. This research is a component of the National Earthquake Hazard Reduction Program.
