San Diego Earthquake Planning Scenario: An Interview with Roberto-Ruiz Salas
If a silver lining is to be found from the COVID-19 pandemic, reconsidering the readiness of our communities to handle unprecedented catastrophes is surely a contender. Before COVID-19, many cities believed their existing infrastructure and disaster relief processes were suitable to handle any unexpected disaster; however, mere weeks after the first confirmed COVID-19 case in the United States, this belief was proven false.
Cities all over the country are now re-evaluating and updating their existing policies to ensure they will be better equipped to handle the next disaster. In particular, cities need to consider their infrastructure’s resiliency against an earthquake catastrophe—an area in which some cities are extremely vulnerable.
Kimley-Horn’s Roberto Ruiz-Salas, P.E., recently worked alongside the Earthquake Engineering Research Institute San Diego Chapter to develop an earthquake planning scenario, studying the impacts of a plausible 6.9-magnitude earthquake if it were to strike the San Diego region today. Below, Roberto shares more about this earthquake scenario, the team’s findings, and how cities can prepare for this natural disaster.
What is an earthquake scenario?
An earthquake scenario is a hypothetical study of what a specific earthquake would do to a region. The scenario is developed by creating a database of existing conditions (i.e., infrastructure, building, and economic factors), coming up with a realistic earthquake that is feasible in the study area, and analyzing the impacts to the infrastructure using a variety of tools and expert judgement.
What scenario did your team study? Why?
We assumed a scenario of a magnitude 6.9 earthquake occurring on the Rose Canyon Fault, which is currently considered the greatest potential seismic threat to the San Diego region due to its active condition and proximity to population, economic, and government centers. We chose this magnitude scenario because it is consistent with historical events, can be expected to occur in the foreseeable future, and is a realistic “worst-case scenario” that would cause widespread damage. It is highly likely that such an earthquake will occur within the next several hundred years, and there is a distinct possibility that it could occur sooner rather than later.
Can you walk us through the process of developing this scenario?
We assembled a team that was divided into three subgroups: Earth Science, Infrastructure, and Socio-Economic.
The Earth Science group—composed of chemists, scientists, geotechnical engineers, biologists, and archaeologists from San Diego, Tijuana, and other regions—first studied the fault line and determined that a magnitude 6.9 crustal strike-slip earthquake was a plausible earthquake for the region.
The Infrastructure group—composed of civil, structural, and traffic engineers as well as public agency officials—created a database of existing structures in the region (i.e., houses, buildings, hospitals, schools, and police and fire stations) and analyzed the impact the magnitude 6.9 earthquake would have on these structures using the FEMA-created software HAZUS.
In addition, Kimley-Horn provided insight into how the horizontal rupture—assumed to be as large as up to six feet—along the fault line may impact utilities. We created GIS maps of the fault rupture compared to the location of utilities, which came from open-source data, and assessed its potential impact. Our traffic engineers assessed the impact to the bridges and highway systems in the region. At the same time, a group of civil engineers across the border in Mexico conducted an analysis of the impacts on houses, manufacturing, and commercial real estate by creating a database of existing structures and using OPENQUAKE by GEM (Global Earthquake Model), a software created in Italy and used around the world for earthquake scenario modeling.
The Socio-Economic group provided a brief analysis about the losses in tourism, work, and export/import the region would suffer as a result of this earthquake.
What was your role on the project?
I became involved in this project in 2014, serving as the project coordinator. I presented updates on our scenario to local, state, and federal agencies, including the San Diego Association of Governments, the City of San Diego, the Office of Emergency Services (OES), the local San Diego Office of Homeland Security, the American Society of Civil Engineers, the American Public Works Association, and the Structural Engineers Association. I also presented updates at the annual earthquake meeting of Protección Civil (the OES’ Mexican counterpart) in Tijuana, Mexico.
What were some of the key findings from this scenario?
The findings are grim overall. The scenario report concludes that the earthquake would result in:
- 7,700 injuries, including 300 fatalities (if the event were to occur at night) and 13,600 injuries, including 800 fatalities (if the event were to occur during the day)
- $38 billion in building and infrastructure damages
- 120,000 buildings suffering moderate to complete damage
- 8,000 buildings damaged beyond repair
- 36,000 displaced households
- Residents cut off from nearly all lifeline utility and infrastructure services with water, wastewater, and gas line services west of the fault rupture zone estimated to be out for months
- Severely impeded transportation lines, causing additional challenges to emergency responders
How can cities prepare for such a devasting, unpredictable event? What about individuals and families?
It all comes down to awareness. A city first must be aware that such an event can take place in the not-so-distant future and affect their constituents, and they must be aware of their existing weaknesses. Only then can they begin to address and mitigate potential challenges. As a starting point, I recommend cities create a Seismic Resilience Working Group that includes government officials, earthquake professionals, private sector utilities, and stakeholders. Then, task them with verifying that every critical area impacted by an earthquake (i.e., infrastructure, water and wastewater distribution infrastructure, power transmission, hospitals and other medical buildings, and school campuses) is assigned a mitigation measure. They can identify these types of buildings throughout their cities and make sure they are structurally sound by today’s standards. Developing a community outreach campaign to ensure residents are educated and prepared for such an event is also a recommended step.
Families need to be prepared for all types of emergencies. Have a plan that at a minimum addresses the following questions:
- If you aren’t together, where will you meet?
- If you aren’t together, what phone number are you going to call to check-in? You must assume that mobile phone lines will be saturated or down in your proximity.
- What is your plan for surviving for 72 hours without outside help?
Visit these sites for more information on earthquake preparedness:
View The Earthquake Engineering Research Institute San Diego Chapter’s full earthquake scenario report.
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