DisasterDemolition of building allows study of earthquake along Calif. Hayward Fault

In an effort to track which area of California’s East Bay would suffer the worst shaking in future earthquakes caused by the dangerous Hayward Fault, the U.S Geological Survey (USGS) initiated an artificial earthquake through the densely populated area of valleys and hills across bay from San Francisco.

Triggered by a building implosion at California State University, East Bay, the seismic waves were recorded by about 500 seismometers arranged in residential backyards and area businesses before the arranged implosion. “This will give us a chance to really improve our shakemap, which is something that comes out immediately after an earthquake to tell first responders which areas are most affected,” Rufus Catching, a research geophysicist with the USGS in Menlo Park, California.

LiveScience reports that the earthquake was made possible by the demolition of Warren Hall (see video here). Of all the buildings in the California State University System, the 13-story Warren Hall was considered to be the building most likely to suffer severe damage during an earthquake. Warren Hall was built about 2,000 feet from Hayward Fault. According to USGS, the fault has a 31 percent chance of producing a 6.7-magnitude earthquake within the next thirty years. To find out where future earthquake shaking may be concentrated, temporary seismometers were placed before the building’s destruction, so they could detect where the sediments in the valley moves rapidly. Ridge effects, which occur when long, narrow mountain ridges amplify shaking, will be monitored by researchers.

The crew also set off a few explosions over the weekend near the California State campus along the Hayward Fault to get a better look at its underground structures. In the exercise, known as a seismic reflection and refraction survey,  a small explosions sets off seismic waves that travel at different speeds through different layers of the Earth’s crust, revealing hidden structures. “We know where the surface break of the [Hayward Fault] is, but we want to determine the width of the fault zone,” Catchings said. “How far it extends from that break affects people who live in that zone.”

The crew, which included volunteers, USGS researchers, and scientists from CSU East Bay, has retrieved data from the seismometers for analysis. Along with the new information and mapping the fault’s pattern, another benefit of the research is the involvement of local residents, their awareness of earthquake risk, and their understanding of USGS’s role.