The M 6.0 South Napa Earthquake of August 24, 2014 took the lives of two people, injured 300 others, and caused moderate to severe damage to more than 2,000 structures. The Commission engaged the Pacific Earthquake Engineering Research Center (PEER) to research the impacts and lessons learned from the quake and prepare a comprehensive report.
The report is organized around the areas of Geosciences, Infrastructure, Buildings, People and Businesses, and Government and Institutions.
The full report is 55 pages with great research and detail. In a later Post we will cover the recommendations, here we provide some of the key findings:
- Afterslip (slippage on the fault after the principal earthquake) on the West Napa fault produced further damage and necessitated regional-scale on-going monitoring.
- The S earthquake identified some critical gaps in mapping coverage and guidance that affected the abilities of city, county, and State agencies to identify and map hazard zones.
- Investments in instrumentation, earthquake alerting systems, and advance remote sensing techniques plus the activation of the California Earthquake Clearinghouse all were valuable in assisting damage assessment and emergency response.
- The earthquake demonstrated the long-term benefits of the State’s $12 billion highway bridge earthquake strengthening program.
- The earthquake highlighted the vulnerability of natural gas transmission and distributions systems to earthquake-related ground failure.
- The earthquake highlighted the vulnerability of water and wastewater systems to earthquakes, plus the hazards that earthquake-related water-system failures can pose.
- The earthquake helped to identify important gaps in building safety evaluations and procedures to barricade unsafe areas.
- The City of Napa’s program to seismically retrofit unreinforced masonry buildings was successful in reducing damage and the risk to life safety posed by these buildings.
- While modern buildings generally met or exceeded code performance standards in the Mw6.0 earthquake, damage to non-structural components was the greatest contributor to property losses.
- There was generally good performance across a range of wood-frame residential construction vintages and styles. The vast majority of damage was caused by two well-known seismic deficiencies: unbraced chimneys and cripple walls foundations.
- The significant damage to manufactured housing in the 2014 South Napa earthquake was almost exclusively associated with support systems rather than the homes themselves.
- People and Businesses
- Deaths and injuries sustained in the earthquake point to continuing gaps in public awareness and education on earthquake safety and preparedness.
- The earthquake highlighted gaps in earthquake insurance coverage for both homeowners and businesses.
- The delay of the federal Individual Assistance program hindered recovery.
- Government and Institutions
- The state’s Standardized Emergency Management System (SEMS) was effective in mobilizing a multi-jurisdictional, multi-level emergency response but significant areas for improvement and training have been identified.
- The earthquake identified problems with the damage assessment and declaration processes and financing of local government post-disaster assistance.
- The earthquake highlighted significant gaps in contingency planning at many key government and critical facility operations.
- More pre-disaster planning and training for post-disaster recovery is needed at both the State and local levels.
Major earthquakes can cause damage and loss, but California has a history of studying and learning from earthquake to make our State safer for residents and businesses. The Commission supported study by PEER is the most recent example of such efforts.