The deadly earthquake in China this week was devastating and felt across a vast area. The epicenter struck central China's Sichuan Province, yet it was felt as far away as Taiwan, Thailand and Vietnam. And its origin was shallow.

In short, it is exactly what seismologists fear could happen in Southern California some day.

Scientists think the Sichuan earthquake was caused by seismic activity associated with the Indian land-mass colliding with the Asian continent (this same force has slowly built up the Himalaya mountain range). Because this week's temblor was relatively shallow — 11.8 miles (19 km) below the ground — it caused especially violent quaking on the surface, which led to extensive damage.

"Some of our worst-case scenarios would involve an earthquake somewhat like this on one of the faults that run through the L.A. region," said Thomas Heaton, a professor of engineering seismology at Caltech. "If we had one like this, it would be a tremendous natural disaster. We would expect to have extensive damage in the several hundred-billion dollar range."

China's shaky past

While this event was horrific, it is not the worst experienced in China's shaky past. A number of Earth's deadliest earthquakes have occurred in China, including what is thought to be the deadliest in history, the 1556 quake in Shaanxi, China. Thought to be about a magnitude-8 event, this disaster caused an estimated 830,000 deaths.

China's last major quake struck the city of Tangshan, near Beijing, in 1976. Though this temblor rated a 7.8 magnitude, less geologically severe than Monday's earthquake (a 7.9 according to the U.S. Geological Survey), it caused far greater damage.

"Tangshan was a horrendous disaster," Heaton said today. "Basically every building in the city was leveled." Official figures put the death toll around 250,000 people, but it was likely closer to 500,000 to 750,000, Heaton said.

So far, the Sichuan earthquake has claimed at least 12,000 lives, and this figure is likely to rise.

Better engineering

Since the Tangshan quake, China has made major changes in their earthquake safety building practices.

"Prior to the Tangshan earthquake, many of the earthquake engineering practices in China were very substandard, but there's been a dramatic change in their attitude about earthquake engineering since," Heaton said.

Even with the best engineering though, much of the Sichuan earthquake damage could not have been avoided, Heaton said. This week's quake was such a profound natural disaster that if it had struck Los Angeles, which takes its earthquake preparations very seriously, it still would have been disastrous.

Though earthquakes in China are not extremely rare, experts could not have predicted this one in advance, Heaton said.

"This was not expected," he told LiveScience. "We can make some maps of where we think you're most likely to see earthquakes over a thousand-year time period, but to predict them over a human time span is pretty tough. You can get old waiting for an earthquake."