Real World Example: Earthquake Risk in Southern California

Prepared by John Taber, IRIS, drawn from materials by Jones, L.M., R. Bernknopf, D. Cox, J. Goltz, K. Hudnut, D. Mileti, S. Perry, D. Ponti, K. Porter, M. Reichle, H. Seligson, K. Shoaf, J. Treiman, and A. Wein, (2008).

Summary

The Los Angeles region is well known for being at risk for earthquakes, with damaging earthquakes in recent memory such as the Northridge earthquake in 1994, that caused 57 deaths and over $20 billion in damage. There is also a general public knowledge that the San Andreas Fault is not far away, and is capable of causing much greater damage. However awareness that a risk exists does not necessarily lead to preparedness.

As part of the ongoing effort to reduce the earthquake risk in southern California, a detailed scenario was developed in 2008 by the USGS and the Southern California Earthquake Center and a team of over 300 scientists, engineers and others (http://pubs.usgs.gov/circ/1324/) . The scenario, which will form the basis of this case study, estimates that a magnitude 7.8 earthquake on the southern San Andreas Fault will cause over 1,800 deaths, 50,000 injuries, $200 billion in damage and other losses, and severe, long-lasting disruption. The scenario has helped focus the effort to prepare buildings, infrastructure and inhabitants in the region for the next "big one".

The case study considers how this scenario has impacted the economic, political, and social aspects of mitigation, response and recovery planning throughout the region, and addresses what future steps are needed to improve southern California's resilience. The case study also addresses the continuing effort to improve the science behind the hazard and risk estimates, and looks at the process needed to put those estimates into a form that can be used to implement engineering solutions and social changes.

Individuals with expertise/responsibilities in the following areas have helped create the case study:

• Engineering
• Seismology
• Emergency response
• Public preparedness/Great ShakeOut
• Regional and state planning

Key teaching points:

• Understanding the basis for, and the limits and uncertainties of the scientific and engineering modelling for the scenario.
• Determining the implications for preparedness where the long term hazard and risk models are well estimated, but the short-term timing is completely unpredictable.
• Determining the best approaches to convince building owners and government planners that short-term expenditures (e.g. retrofitting, building new structures to a higher standard) will create longer-term benefits to society.
• Analyzing the impact the Great ShakeOut earthquake drills (http://www.shakeout.org/) have had on earthquake risk mitigation in the public, private, and government sectors.

Recommended Readings

Southern California Earthquakes Example (detailed information) (Microsoft Word 2007 (.docx) 492kB May19 14) - important background information for the example.

Jones, L.M., R. Bernknopf, D. Cox, J. Goltz, K. Hudnut, D. Mileti, S. Perry, D. Ponti, K. Porter, M. Reichle, H. Seligson, K. Shoaf, J. Treiman, and A. Wein, 2008, The ShakeOut Scenario, U.S. Geological Survey Open File Report 2008-1150. http://pubs.usgs.gov/of/2008/1150/.

Perry, S., D. Cox, L. Jones, R. Bernknopf, J. Goltz, K. Hudnut, D. Mileti, D. Ponti, K. Porter, M. Reichle, H. Seligson, K. Shoaf, J. Treiman, and A. Wein, 2008, The ShakeOut Earthquake Scenario—A Story That Southern Californians Are Writing, U.S. Geological Survey Circular 1324, http://pubs.usgs.gov/circ/1324/.

Wein, A. Adam Z. Rose, 2010, Economic Resilience Lessons from the ShakeOut Earthquake Scenario, CREATE Research Archive, Published Research Reports.

Wood, M. W., 2013, Engaging Californians in a Shared Vision for Resiliency: Practical Lessons Learned from the Great California Shakeout, California Seismic Safety Commission, report 13-02, .http://www.seismic.ca.gov/pub/CSSC_13-02_ShakeOutRecommendations.pdf