You hear the phrase "implode" all the time, but what does it really mean? Now you can find out, in this video of a Cal State Hayward building being neatly demolished over the weekend.

This video from Adam Parmalee shows how quickly the whole thing happened. The building, called Warren Hall, had been deemed seismically unsound — and on top of that, it's only about 2,000 feet from California's dangerous Hayward Fault. The university decided to demolish Warren Hall rather than pay for an expensive retrofit. But that didn't prevent earthquake engineers from using the destruction to learn something.


Over on SF Gate, Victoria Colliver explains the engineering that went into this incredible implosion:

Taking down the building posed an engineering challenge because of the tower's proximity to the library and several other campus structures. The demolition contractor placed the specially timed charges so the building would lean and keep the 12,500 tons of concrete rubble and steel away from the other buildings.

All went as planned, except for a 60-foot-high section of the northeast portion of the building that remained more upright than expected. University officials said that piece would be demolished sometime during the cleanup period, which may last as long as 60 days.

"Everyone is absolutely thrilled," said Jim Zavagno, associate vice president in charge of facilities for the campus. "It's pretty amazing they were able to take down the building in such a small area."

The U.S. Geological Survey took advantage of the blast, which essentially mimics a minor earthquake, to allow researchers to more carefully study and map the Hayward Fault.

USGS crews placed more than 600 seismometers, instruments about the size of tall beer cans, around the neighborhood to register seismic activity. The implosion, which created the equivalent of a magnitude-2.0 earthquake, gave scientists the opportunity to know well in advance exactly when and where the seismic event would occur.

"If you know which areas are known to have greater amplification, for homeowners that's golden information, because they can do things that can help them prepare for a real event," said Rufus Catchings, a USGS geophysicist and lead scientist for the experiment.

Read more on SF Gate.