Hayward building demolition to be studied
- June 20, 2013
By David Perlman
Chronicle Science Editor
A 40-year-old landmark building in the East Bay is slated for demolition in a single big blast this summer, and the event will give earthquake scientists an unexpected chance to study new aspects of the long-feared Hayward Fault.
Warren Hall stands 13 stories high on the Hayward campus of Cal State East Bay, and it has been doomed for more than two years since it was deemed the most seismically dangerous structure in California's state university system.
Demolition experts are planning to destroy the building from the inside out in one massive explosion - tentatively scheduled for late August - and the blast is expected to create a small earthquake that could register as high as 2.5 magnitude, according to rough estimates by geophysicist Rufus Catchings of the U.S. Geological Survey in Menlo Park and his Cal State colleagues.
Earthquakes that size are common throughout the Bay Area in the San Andreas Fault zone, and most are unfelt except for mild local shaking, seismic records show.
Catchings is directing a series of earthquake experiments resulting from the Warren Hall demolition project, along with Cal State geologists Luther Strayer and Mitchell Craig, and John Evans of the Geological Survey. Scores of scientists have volunteered for the research effort.
Their research goal, Catchings said, is to find ways for improving safety from major quakes in areas where the Hayward Fault is of major concern.
The researchers will place more than 500 temporary seismographs and other instruments in wide concentric circles around Warren Hall, Catchings wrote in an e-mail from Greece, where he is vacationing.
"During future earthquakes ground shaking should vary greatly in the area, from the hard rock of the Hayward hills, the soft sediments of the East Bay plain, the 'low-velocity' rocks of the Hayward fault zone, and the peaks within the Hayward hills," he said.
The researchers hope to look at those varied effects in detail so they can understand more clearly how similar terrain would behave in real quakes, Catchings said.
Catchings said his team also plans to generate several "controlled shaking" events during the experiment, including dropping weights to the ground, shaking the ground with machines and possibly using very small explosions in the unsettled earth.
"This will help us to determine the relationship between the Hayward Fault and other possible buried faults beneath the bay and the nearby Calaveras Fault," he said.
Meanwhile, he said, Geophysicist John Evans of the USGS plans to deploy instruments known as tiltmeters on the piles of rubble left by the demolition blast "to see if there are clear signs of further settling in the pile."
If that effort succeeds, recorded insights into the behavior of the ground and building ruins after quakes could provide valuable information for first responders in emergencies after future quakes, Catchings said.
The delicate job of blasting Warren Hall into ruins will be done by Silverado Contractors of Oakland, a veteran crew of demolition specialists. California State University trustees have appropriated $50 million for the destruction and its replacement: a seismically stronger, five-story structure built in precast concrete, glass, and steel.
The research effort exploiting the demolition came about purely by coincidence, said Strayer, a geologist who studies natural structures like mountains and ridges, but not earthquakes.
"Quakes aren't really my field," he said, "but when I heard about the demolition and was passing by Warren Hall, I thought to myself, 'Boy, that's going to make a really loud boom.' So I passed the word to the Geological Survey folks, and that started things going."
David Perlman is the San Francisco Chronicle science editor.
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