As my colleague Mohsen Rahnama reminded us in his recent blog, the last destructive earthquake to strike Northern California was on October 17, 1989. Loma Prieta was a magnitude 6.9 earthquake which resulted in 63 deaths and about four thousand injuries. The epicenter was about ten miles northeast of Santa Cruz, and seismic waves took about 30 seconds to reach San Francisco. But there was no way of communicating any earthquake early warning to residents of the Marina district of San Francisco, which suffered some of the worst damage from shaking and fire outbreak.
On October 17, 2019, the thirtieth anniversary of this earthquake, the California Governor’s Office of Emergency Services unveiled a smartphone app from the University of California, Berkeley Seismological Lab that will give all Californians the opportunity to receive earthquake early warnings.
Governor Gavin Newsom, who happened to be in the Marina district at the time of the 1989 earthquake, has urged people to download the MyShake app. This app (myshake.berkeley.edu) is available on the Apple App Store and Google Play, and relies on the ShakeAlert earthquake early warning system, developed by the U.S. Geological Survey (USGS).
Thirty years ago, the Mw6.9 Loma Prieta Earthquake
struck the San Francisco Bay Area. When looking back at disasters, it is always
particularly relevant to understand the moment in time impacted. The Loma
Prieta Earthquake struck on Tuesday, October 17, 1989 at 5:04 p.m. local time,
but it was no ordinary Tuesday afternoon. Game Three of the Major League
Baseball 1989 World Series was to start at 5:35 p.m. between the two Bay Area
teams: the Oakland Athletics and the San Francisco Giants.
Typically, 5:04 p.m. would represent the height of rush hour in the Bay Area, but because of the game a significant component of the workforce had left work early or had stayed late to watch it. While 63 lives were lost, this loss level was much lower than it might have been given the level of damage that impacted highways across the region including the failures of the Nimitz Freeway and the San Francisco–Oakland Bay Bridge.
I was at Stanford University in the Terman Engineering Building studying when the earthquake struck. The Stanford campus made up of numerous historical buildings saw substantial damage. In all, more than 200 structures were impacted. The restoration of the damage took more than a decade to fix and cost Stanford more than US$160 million. Classes were canceled for more than a week. Students were locked out of damaged buildings which meant they could not access their research samples, data and equipment. Adding to the stress were the innumerable aftershocks. For those of us studying engineering, it really brought home the importance of our work.
With the recent August 24, 2014 M6.0 Napa Earthquake, the San Francisco Bay Area was reminded of the importance of preparing for the next significant earthquake. The largest earthquake in recent memory in the Bay Area is the 1989 Loma Prieta earthquake. However, in the event of a future earthquake, the impacts on property and people at risk are higher than ever. Since 1989, the population of the region has grown 25 percent, along with the value of property at risk, and according to the United States Geological Survey, there is a 63 percent chance that a magnitude 6.7 or larger earthquake will hit the Bay Area in the next 30 years.
The next major earthquake could strike anywhere – and potentially closer to urban centers than the 1989 Loma Prieta event. As part of the commemoration of the 25th anniversary of the earthquake, RMS has developed a timeline of events could unfold in a worst-case scenario event impacting the entire Bay Area region.
In the “Big One’s” Aftermath
This black swan scenario is extreme and is meant to get the stakeholders in the earthquake risk management arena to consider long-term ramifications of very uncertain outcomes. According to RMS modeling, a likely location of the next big earthquake to impact the San Francisco Bay area is on the Hayward fault, which could reach a magnitude of 7.0. An event of this size could cause hundreds of billions of dollars of damage, with only tens of billions covered by insurance. Without significant earthquake insurance penetration to facilitate rebuilding, the recovery from a major earthquake will be significantly harder. A cluster of smaller earthquakes could also impact the area, which, sustained over months, could have serious implications for the local economy.
While the Bay Area has become more resilient to earthquake damage, we are still at risk from a significant earthquake devastating the region. Now is the time for Bay Area residents to come together to develop innovative approaches and ensure resilience in the face of the next major earthquake.