Performance of Buildings and Nonstructural Components

February 2015. Applied Technology Council, FEMA.

The magnitude-6 South Napa earthquake occurred on August 24, 2014 with an epicenter located 8 km (5 miles) south southwest of the City of Napa. The cities of Napa and Vallejo, as well as the surrounding areas, were significantly impacted by the event. The earthquake struck at 3:20 in the morning, which was the primary reason for only one fatality and the low number of serious injuries. Had the earthquake struck 12 hours earlier, during a street festival in downtown Napa, the number of fatalities could have easily been in the hundreds due to falling debris from masonry buildings and nonstructural components.

The earthquake was recorded by eight strong-motion recording instruments at which horizontal ground motions were significant (exceeded 0.1g), and three of those instruments were located within the City of Napa. Availability of recorded ground motions and documentation of the impact of the earthquake provides an excellent opportunity to calibrate and evaluate existing earthquake hazard reduction methodologies. This is also an opportunity to expand existing knowledge and databases on the performance of buildings and other structures, including seismically retrofitted unreinforced masonry (URM) buildings.