On October 17, 1989 the Loma Prieta earthquake of moment magnitude 6.9 (‘strong’) on the Gutenberg-Richter scale and IX (‘violent’) on the Mercalli scale, with 19 km deep focus, and epicenter located 127 km south of San Francisco Bay Area in Nisene Marks State Park, California, caused the deaths of 63 people, injured another 3,757, and destroyed building and bridges in the Bay Area (Glough 1994).