The upgrade to magnitude 7.1 means there was about 25% more vibration going on than originally thought. Quake watchers also thought that the derailed Amtrak train, with its few minor injuries, was the worst of it.
It wasn't the half of it.
This major quake happened on a minor fault previously considered inactive, far off in the desert bothering no one.
As Lucy Jones of the US Geological Survey, explains, "Basically, we didn't go back there, because it's only rattlesnakes that really care."
Not anymore. This obscure fault released more power than a conventional nuclear blast. It was the fourth largest quake in southern California this century, and it ripped a 25-mile gash in the desert floor.
The science of earthquakes is imprecise, but this one has scientists looking at their data again.
The Northridge fault was unknown until it shuddered to life in 1994 with a 6.7 quake, killing 57 people and causing $40-billion in damage.
How could scientists have missed it? "There are an awful lot of faults," says the U.S. Geological Survey's Kenneth Hudnut. "What we do is like triage; find the ones that have the highest hazard and deal with them."
The scientists had a new tool this time: the Internet, which took in information about the quake from ground sensors and sent it out instantaneously--information which used to take hours, even days, to obtain.
"We're able to see much more clearly what ground motions are created by this type of big event," says Jones.
It's still helping track of all the aftershocks and may someday help save lives.