Tremors rattle in memories
Recollecting details of temblor after 20 years reveals deficiencies in disaster preparedness
Published: Wednesday, October 14, 2009
Updated: Wednesday, October 14, 2009 19:10
Earlier that Tuesday evening, she walked about her Oakland home, a five-month-old infant the focus of her attention. While preparing to pack for a flight to Seattle later that night, Rose Muller felt something.
"The walls just started undulating. Everything started jumping off," she said. "I ran outside with my baby, because I didn't know if the building was going to collapse."
Muller said the walls took a nearly liquid-like appearance.
"It was really scary," she said.
The Contra Costa College nursing major's experience was no isolated incident, as the 6.9 moment magnitude 1989 Loma Prieta earthquake, which marks its 20-year anniversary Saturday, created countless similarly frightening instances.
Revealing the weaknesses
Felt as far south as San Diego and up through Sacramento County, it caused 63 deaths, 3,757 injuries and roughly $6-$10 billion in property damage, according to the United States Geological Survey (USGS).
Birthed along the San Andreas Fault in an unpopulated forest of the Santa Cruz Mountains, the temblor shook the college, but luckily led to little more than a few items falling off of shelves.
Although the epicenter was in Santa Cruz County, much of the destruction occurred in the Bay Area, with 42 fatalities alone resulting from the collapse of the Interstate 880 Cypress Street Viaduct in Oakland.
"The earthquake occurred in the Santa Cruz Mountains, yet some of the most dramatic (effects) happened in the Marina (District of San Francisco) and Bay Bridge and Cypress structure," said Susan Tubbesing, executive director of the Earthquake Engineering Research Institute (EERI). "That really brought to everyone's attention the effect of soil conditions."
Chuck James, information systems manager for the National Institute for Earthquake Engineering, said the failure of the Cypress structure was due to its construction on soft mud. Similarly, more buildings in the Marina District fell under their own weight because many were built on uncompacted, sandy ground. These sand deposits saturated with nearby water sources, in a process known as liquefaction, to form a slurry that served as a poor foundation, James said.
Dr. David Schwartz, coordinator for the National Earthquake Hazards Reduction Program for Northern California, said the earthquake and its devastating effects provided important lessons for California and shook a lot of institutions out of their complacency.
"(The earthquake) was a shot across the ship's bow, and a warning that we've got big earthquakes down the road," Schwartz said. "Caltrans has done a lot with bridges and freeways. (Pacific Gas and Electric) has upgraded its substations and transmission lines. East Bay (Municipal Utility District) and the San Francisco Public Utilities Commission have been retrofitting the locations where there are major pipelines along the faults."
Regarded by the EERI as the most dangerous and soon-to-erupt fault in the nation, the Hayward Fault has prompted numerous changes in local, state and federal policies.
The fault, which cuts into the CCC campus through Lot 10, Lot 1 and the Bus Transfer Center and can be seen above ground in the line of cracks and diverted sidewalks, has not had an earthquake since 1868.
Schwartz said that if an earthquake were to happen on the Hayward Fault today, the damage would be much more extensive than that of the Loma Prieta temblor. The USGS estimates that more than five million people would be affected and more than $165 billion of property damage would likely occur.
Various legislation has been passed to address this fear, such as the 1972 Alquist-Priolo Special Studies Zone act, which requires the California Division of Mines and Geology (now known as the California Geological Survey or CGS) to compile detailed maps of the surface traces of known active faults and prohibits construction of houses within these zones unless a geologic investigation shows that the fault does not pose a hazard to the proposed structure.
Also, the California Seismic Hazard Mapping Act of 1990 establishes that the CGS produces maps showing areas where potential earthquake-induced landslide and liquefaction hazards exist and requires studies to identify if these hazards are present prior to certain types of land development or construction.
These acts played heavily into the creation of the college's Facilities Master Plan, which calls for some form of demolition, construction and retrofitting for every building on campus, Buildings and Grounds Manager Bruce King said.
In order to build new structures, the college had to conduct trenching near the Student Activities Building, behind the Humanities Building, near the tennis courts and by the Comet Stadium concession stand, King said. Holes roughly 20-feet deep were dug in regions near the fault to survey soil and ultimately determine future fault activity in that particular area.
Following the testing, the college was given approval to rebuild the SA Building just slightly farther toward the H Building, given that it fits seismic safety standards, King said.
Also, the Liberal Arts Building and Library Learning Resource (which was almost completely demolished before being rebuilt and reinforced), Computer Technology and Early Learning centers have all been seismically retrofit, King said.
"(Retrofitting) helps ensure our safety," he said.
But, although additional structures that needed seismic retrofits, such as the Applied Arts and Music buildings, have tentative dates set for completion, King said others in need of remodeling do not. These include the Gymnasium and Physical Sciences, Biological Sciences and Gym Annex buildings.