By Elizabeth Weise
SAN FRANCISCO - Scientists monitored the impact as a 13-story building crashed to the ground Saturday in the hopes they could learn more about earthquakes.
Researchers used the demolition of the largest building on the Cal State-East Bay campus in Hayward, Calif.,as a natural experiment. The collapse created a small shock wave that they could measure across the region.More than 6,000 sensors were deployed within a mile or two of the building to record the wave as it raced through the ground. Others were as far away as San Francisco, located about 20 miles southeast of campus.
"We got some pretty strong shaking in the general area," said Rufus Catchings, a geophysicist with the U.S. Geological Survey in Menlo Park, Calif., who wasone of dozens of scientists who had spent the past month getting ready for the demolition.
All 12,500 tons of Warren Hall went down just after 9 a.m. Saturday "without a hitch," said Barry Zepel, a spokesman for the university. About 1,000 people gathered in the parking lot of a nearby Kmart to watch in what became something of a tailgate party.
"Because our library is about 50 feet away, they meant for it to come down with a slight tilt to the west, and that's what it did," Zepel said.
Because shock waves travel through solid rock differently than through the broken rock and soil of fault lines, the researchers hope that when they analyze their measurements they'll get a better sense of the extent of the Hayward fault zone, about which little is known.
USGS staffers had specifically requested television news crews not to use helicopters to film the event because the roar and "thump-thump-thump" of the blades could have drowned out the small signal created by the implosion they were trying to record.
The building was scheduled for demolition after being tagged as the No. 1 earthquake risk in the 23-campus California state university system because of the way it was built and its proximity to the Hayward earthquake fault, Zepel said.
The building "wasn't the most attractive," but it was the campus' signature structure, visible from the freeway and even from across the San Francisco Bay, Zepel said. It will be replaced with a lower building on the other side of campus.