The ShakeOut Scenario
The ShakeOut Scenario, completed in May, 2008, is the first major product of the USGS Multi-Hazards Demonstration Project. This scenario designed a plausible earthquake on the southern San Andreas Fault and then studied its effects, from the direct physical impacts to the long-term, social, cultural, and economic consequences. Immediately after publication, it is already clear that the ShakeOut Scenario is making a difference. It has identified key strengths and vulnerabilities in southern California’s readiness for major earthquakes, and this has already launched discussions that are the first step toward correcting problems. It has encouraged new discoveries and applications in research fields as diverse as earthquake physics and disaster economics, broadening the foundation for future advances. And it has inspired the largest ever participation in earthquake preparedness drills, among both the emergency response community and the general public.
The ShakeOut Scenario: Focus Shift
The ShakeOut Scenario considered impacts to an eight-county region (Riverside, San Bernardino, Los Angeles, Orange, Ventura, Kern, San Diego, and Imperial Counties). In summer, 2008, additional research will be conducted to evaluate the earthquake’s impacts for particular communities and stakeholders.
Golden Guardian Planners
In May 2008, ShakeOut Scenario scientists handed off their results to planners developing November response exercises. ShakeOut Scenario scientists remain engaged in the exercise planning process, to make sure that planners have the tools and information they need to make full use of the ShakeOut Scenario.
Business Planning
An evaluation of decision-making processes as businesses plan for the ShakeOut Scenario earthquake.
City of Palm Springs
A look at impacts of the ShakeOut Scenario earthquake on emergency response and recovery in an area that would undergo strong shaking during this particular earthquake.
City of Torrance
Consideration of the economic impacts of the ShakeOut Scenario earthquake on an area that would experience relatively mild shaking during this particular event.
Largest Aftershocks
The ShakeOut Scenario project generated realistic simulations of aftershock sequences. Some of these aftershocks will be larger and potentially more devastating than the 1994, magnitude 6.7 Northridge earthquake. For certain large aftershocks that will be part of the Golden Guardian exercises, ShakeOut scientists are creating estimates of shaking and consequences.
SoSAFE Underway
The goal of SoSAFE (Southern San Andreas Fault Evaluation) is to reduce the uncertainty in earthquake hazard by determining the rupture chronology and slip rates of the Southern San Andreas fault system for the last 2,500 years. A planning workshop was held in January 2007 to prioritize the research plan. Early results appear promising in several areas. First, the Frazier Mountain site has yielded new evidence for 4-5 past events and datable layers has been sampled. Second, dates from the Coachella site and Bidart site have allowed new interpretations of event evidence in the Coachella Valley and Carrizo Plain. A second major SoSAFE workshop was held in Palm Springs on September 9, 2007, at which time initial results from SoSAFE’s first year of funding were presented.
When designing the ShakeOut earthquake, the ShakeOut Scenario was able to take advantage of the expertise assembled at SoSAFE workshops.
Earthquake Early Warning
Late in 2007, MHDP participated in discussion with Caltech, U.C. Berkeley, and the USGS to create an Earthquake Early Warning System. As contributors and end-users have considered the results of the ShakeOut Scenario, the discussion about earthquake early warning has been re-engaged, in examining how it might mitigate injury, property damage, and the loss of life in the ShakeOut earthquake.
Tsunamis from Local Earthquakes
In 2008, as part of the MHDP, USGS tsumani scientists began to analyze southern California’s hazard from tsunamis generated by local earthquakes. A reconnaissance mission launches the effort to identify offshore faults capable of generating significant tsunamis. USGS scientists are focussing their analysis on faults that are associated with offset seafloor. These include thrust faults with folds in the hanging wall that deform the sea floor, and right-lateral strike-slip faults with sea floor relief evident at bends or steps in the fault zone. The first priority are the blind thrust faults beneath the Santa Barbara Channel, which has a history of local, fault-generated tsunamis. Following efforts will consider the Rose Canyon Fault to the Newport-Inglewood fault; and the San Diego Trough Fault to the Catalina Fault.
Results from the modeling will including animations, to be presented on the web with updates as new results become available.
