News Release #2008-06
March 7, 2008
Contact: Don Drysdale
LONG BEACH – Seventy-five years ago on March 10, the Long Beach earthquake claimed 120 lives and caused $50 million (1933 dollars) in property damage. The quake was particularly damaging to schools, triggering important public safety legislation and improved design and construction practices.
“As we commemorate one of California’s most devastating natural disasters, we should note that some good came of it and also remember the date of April 10, 1933,” said State Geologist Dr. John Parrish, head of the California Geological Survey (CGS).
Just a month after the quake struck, the Legislature passed what came to be known as the Field Act. California Assemblymember Charles Field sponsored the bill that required earthquake-resistant design and construction for public schools, kindergarten through community college.
“The Field Act specified that the state would review and approve all public school plans and specifications, and to generally oversee all construction work,” said David Thorman, the State Architect. “Buildings constructed under the Field Act’s requirements have been put to the test by a number of subsequent earthquakes, and no school built under the Field Act’s guidelines has failed in an earthquake.”
The Division of the State Architect (DSA) provides design and construction oversight for K–12 schools and community colleges. At DSA’s request, CGS’ School Review Project evaluates the geology of proposed school sites or new structures on existing sites. Factors such as predicted seismic ground shaking; landslide, liquefaction and tsunami potential; and other unsafe soil conditions are taken into consideration. CGS reviewed about 350 projects in 2006-07.
“School site reviews are one of the most important services we provide to local communities,” Parrish said. “The partnership between DSA and CGS has made California’s school buildings among the world’s safest.”
School districts contract with private-sector experts to prepare geologic hazard and geotechnical reports when they are selecting new school sites or making additions to existing schools. Once the project is in the design stage, structural engineers need a more detailed site analysis to design buildings with the appropriate foundation for the geological conditions at the building site. That’s when CGS’ reviewers go to work, making sure that the guidelines for conducting an appropriate investigative study have been followed.
The guidelines, set forth in CGS Note 48, recommend geologic investigations include onsite drilling exploration and soil testing to a depth of 50 feet; a calculation of potential ground shaking based on the best scientific and engineering information available; and an evaluation by a geotechnical engineer and a certified engineering geologist.
“Perhaps a fifth to a quarter of the time we send the reports back asking for more information or asking that additional concerns be addressed,” said State Seismologist Dr. Michael Reichle. “With the current level of professionalism in school design, major geological concerns are thoroughly considered. Student safety is foremost on everyone’s mind when it comes to school building projects.”
The 1933 earthquake wasn’t particularly large; at magnitude 6.3, it was significantly less powerful than the later Loma Prieta, Northridge or San Fernando quakes. But it was the second-deadliest in California history after the 1906 Great San Francisco Earthquake, which predated modern instruments but is estimated to have been in the magnitude 8 range.
As significant as the death totals were in the Long Beach quake, a major impetus for change was the fact that 70 schools were destroyed and 120 damaged. Five students were killed in collapsed school buildings and a 13-year-old sitting with friends on the steps of her Garden Grove high school was crushed by a falling wall.
“The earthquake occurred at nearly 6 p.m. – if it had happened a few hours earlier, the results could have been far more devastating” DSA’s, David Thorman said.
In an article for “California Geology” magazine commemorating the 40th anniversary of the quake, Compton resident and former deputy chief of the California Division of Mines and Geology (CGS’ predecessor) Gordon B. Oakeshott wrote of the destruction he witnessed first-hand:
“… in 1933 I was teaching surveying and the Earth sciences at the (Compton junior) college and so have poignant memories. Our three-story high school and college classroom and administration building was so badly damaged that it had to be razed and rebuilt. My basement classroom was filled with rubble and a central chimney structure had come down through classrooms on two floors into the basement. … Compton College’s beautiful, tile-roofed arcades between buildings collapsed completely. The great and lasting good that came from the tragic and scandalous failures of school structures in this earthquake was the passage of the Field Act … I say `scandalous’ failures because the strong shaking of the earthquake revealed `shortcuts’ in construction practices, as well as design, in many school buildings.”
The Field Act has been updated to include retrofits since 1933. As of 1974, all pre-Field Act schools in the greater Los Angeles area have been retrofitted.
“The Field Act deserves praise for saving many lives, but there still are unreinforced masonry buildings throughout California that would be dangerous in an earthquake of similar magnitude to the Long Beach earthquake,” Parrish said. “The commemoration of the Long Beach quake is not only a time to reflect, but also a time to look forward at the work that remains to be done and to think about the need to be prepared. Every day that goes by without a large, damaging earthquake puts us one day closer to the next one.”
Scientists, Parrish noted, try to learn something from every damaging quake. That knowledge is reflected in things such as stronger building codes and improved emergency response. Ultimately, though, how Californians fare in the next large earthquake may come down to personal preparation.
“Earthquakes typically strike without warning and can happen at any time,” Parrish said. “Although government agencies such as DSA and CGS, academia, and private industry all are working to protect public safety, people are well advised to prepare at the individual and family level, too.”