An earthquake with a magnitude similar to the one that recently rocked China is inevitable in Southern California and could cause about 2,000 deaths, 50,000 injuries and $200 billion in damage if it happened today, the U.S. Geological Survey and the California Geological Survey warn in a new report.

In the study, “The ShakeOut Scenario,” released Thursday, scientists examine the effects of a hypothetical 7.8-magnitude earthquake along the San Andreas fault on the region’s physical infrastructure and economic and social systems.

“The question is not if but when Southern California will be hit by a major earthquake — one so damaging that it will permanently change lives and livelihoods in the region,” the report said. “Unlike many other faults, the southern San Andreas fault produces no small earthquakes.”

The study, prepared by scientists, government officials, emergency responders and utility experts, predicted major freeways and railways would be severed.

“An earthquake of this size and scope is inevitable in Southern California, and we are simply not ready for it,” said Sue Perry, a USGS staff scientist who contributed to the report. “An earthquake of that size could be the Katrina of Southern California.”

The scientists prepared a hypothetical model in which the quake occurs on Nov. 13, 2008, at 10 a.m., starting near the eastern shore of the Salton Sea and traveling northwest along the fault at two miles per second. A narrative, much like a movie script, depicts the “realistic outcome” of the quake.

The temblor would disrupt the movement of goods to and from major ports; manufacturing plants would halt production and face additional costs to transport goods out of the region; and hundreds of older commercial office buildings would crumble.

There has not been a devastating temblor in urban California since the 6.7-magnitude Northridge quake in 1994, which killed 57 and caused about $40 billion in damage.

The report said Southern Californians “have the opportunity to work together to write this ending … through the decisions they make or don’t make to get ready for earthquakes.”

The recommendations include storing water, increasing volunteer preparedness and collaborative planning, retrofitting problem buildings and strengthening infrastructure.