Major Quake Likely to Strike Between 2000 and 2030
by Andrew J. Michael, Stephanie L. Ross, David P. Schwartz, James W. Hendley II, and Peter H. Stauffer
United States Geological Survey
On the basis of research conducted since the 1989 Loma Prieta earthquake, U.S. Geological Survey (USGS) and other scientists conclude that there is a 70% probability of at least one magnitude 6.7 or greater quake, capable of causing widespread damage, striking the San Francisco Bay region before 2030. Major quakes may occur in any part of this rapidly growing region. This emphasizes the urgency for all communities in the Bay region to continue preparing for earthquakes.
Just before dawn, residents of a bayside urban area, thought to be well prepared for earthquakes, were jolted from their beds by a magnitude 6.9 quake. This 1995 temblor killed more than 6,000 people and caused $100 billion in damage. The quake struck Kobe, Japan, but similar losses could have occurred in the San Francisco Bay region in 1989 had the magnitude 6.9 Loma Prieta earthquake been centered in an urbanized area.
Damaging earthquakes are inevitable in the Bay region, but taking actions based on the odds of future quakes will help save lives and protect property. Following the Loma Prieta quake, the U.S. Geological Survey's (USGS) Working Group on California Earthquake Probabilities reassessed the likelihood of large quakes striking the Bay region and issued a report in 1990.
Since then, scientists have gained new insights into Bay region earthquakes, providing a better basis for determining quake odds. In 1997, the USGS working group, now known as WG99, was expanded to include more than 100 scientists from Federal and California State governments, consulting firms, industry, and universities.
http://www.wsspc.org/pubs/news/eq9911.htm#USGS