The Free Press, Mankato, MN

State, national news

August 17, 2013

SF Bay Area building demolition fuels quake study

HAYWARD, Calif. — It took just seconds for a 13-story building overlooking San Francisco Bay to implode, spewing smoke and chunks of concrete as it crumbled into a heap of rubble. But U.S. Geological Survey scientist Rufus Catchings was marveling less at the visual spectacle than what he could feel with his feet.

As the building collapsed, the vibrations Catchings noted told him that a novel experiment to study one of the most dangerous fault lines in the country likely was a success.

"I was trying to sense the seismic energy on the ground," Catchings said.

On Saturday, workers imploded Warren Hall, for four decades a fixture of the East Bay hillsides and the Cal State East Bay campus.

The boxy building was built roughly 2,000 feet from the Hayward fault, and officials recently deemed it seismically unsafe. Scientists turned its destruction into a valuable tool in their ongoing efforts to understand the earthquakes that have shaped California.

At precisely 9 a.m. a series of explosives went off with deafening bangs, as the building shook and then slumped. Then Warren Hall crumbled into a 12,500-ton pile of concrete and steel.

Scores of onlookers cheered.

The impact sent shockwaves that researchers hoped would mimic a magnitude-2.0 earthquake. Scientists had placed more than 600 miniature seismographs in concentric circles within a mile of the building to collect data they will use in their studies.

"This will tell us a lot about the fault zone itself, of the amplitude of seismic energy we expect from a real earthquake," Catchings said.

The USGS estimates there is a 63 percent chance of a major earthquake in the Bay Area within the next three decades.

The Hayward fault, which runs through several East Bay cities and under the football stadium at the University of California, Berkeley, is the most likely of the handful of Bay Area fault lines to move.

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