Quake 2003 Scenario Background

For the Quake 2003 scenario, we selected a magnitude 6.5 earthquake on the northern Hayward fault. This event should fall between the "occasional" and "rare" events used by Mary Comerio and her co-authors in The Economic Benefits of a Disaster Resistant University.

An earthquake of this size would cause considerable damage in the East Bay, although it is likely to be less damaging than many other potential events. For comparison, the 1989 Loma Prieta earthquake was an M6.9. According to the new earthquake probabilities, there is 62% probability of one or more earthquakes of M6.7 or greater from 2003 to 2032 in the San Francisco Bay Area.

This segment of the Hayward fault has not ruptured during "historical" time, that is, it has not ruptured since the mid 1700s. In contrast, the southern Hayward fault last ruptured in the 1868 earthquake. The scenario rupture runs from south of Berkeley into the Bay north of Richmond. This scenario is one of several scenarios developed by the USGS as part of the earthquake probability study.

For Quake2000, we developed a scenario for an M6.7 earthquake on the southern Hayward fault. Although that event was larger, this earthquake includes half a meter of fault rupture through ' the campus, causing damage to the Stadium and other buildings near the fault.

The aftershock probability was calculated by Dr. Lind Gee using the software of Dr. Paul Reasenberg of the USGS. This is the same software used to generate reports after earthquakes in northern California, and is based on the statistics of California earthquakes.

The ground motion maps or ShakeMaps were computed by the USGS as part of their earthquake scenario development. The maps display the amount of ground shaking predicted for the event. The ShakeMaps are extremely useful for diaster planning - although these maps do not include the effects of directivity (how the direction of the fault rupture influences the ground shaking ) or the impact of wave propagation in 3-dimensions. For the Quake 2000 scenario, we used ground motion maps developed by Dr. Asya Kaverina and Prof. Doug Dreger that included the effects of rupture direction and 3-d geologic effects. You can compare those ground motion maps - and see the resulting movie.

The HAZUS damage and loss estimates were computed by Ms. Johanna Fenton, a GIS Analyst in the Governor's Office of Emergency Services, using Alameda and Contra Costa counties as the study area and do not include damage in other Bay Area counties. The HAZUS runs are based on the ShakeMap ground motions.

If this had been a real event, the UC Berkeley/USGS joint earthquake notification system (part of the California Integrated Seismic Network would provide information about the earthquake's location, magnitude, and extent of strong-ground shaking. At UC Berkeley, earthquake processing is handled by the Rapid Earthquake Data Integration (REDI) system, which provides rapid access to earthquake information. Typically, a preliminary location is available within 30 seconds after an event. This is followed by a revised location within 2-4 minutes with a preliminary magnitude. This is followed by a revised magnitude within a minute. This figure illustrates the typical flow of information following an earthquake.