It's Been Awfully Quiet Lately Here On The Northeastern Quadrant Of The Pacific's "Ring Of Fire"

Let's see: Chile, New Zealand, American Samoa, and now Japan. Southeast, southwest, northwest. But here, on the northeastern quadrant, things seem peaceful. Looks can deceive, of course:

"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," according to a 2008 study by the United States Geological Survey study.

It predicted 2,000 deaths and $200 billion in damage from a 7.8 southern California quake on the San Andreas Fault.

...A monster California quake of magnitude 8 had only about a 4 percent probability -- except in far Northern California and the Pacific Northwest. That area has a 10 percent chance of experiencing a magnitude 8 to 9 quake -- Japan-sized -- in the next 30 years.

A repeat of San Francisco's 7.9 magnitude quake in 1906 could take up to about 900 lives, injure thousands and destroy 3,000 residential buildings, a recent report for the city found.

Even a smaller 7.2 quake would cause $30 billion in building damage, $10 billion more in additional costs -- and if fires sweep the city, damage could rise by $4 billion, the report sponsored by the San Francisco Department of Building Inspection concluded. About 27,000 of the city's 160,000 buildings would become unsafe to occupy.

One of the authors of the report, geotechnical engineer Thomas Tobin, reflected that the hot winds of Santa Ana winds blowing from the desert into Los Angeles could intensify a disaster created by a southern California quake.

"If it happens to be a large earthquake on a hot, dry day with the wind blowing, the losses could be huge," he said.

COLLAPSING BOX

Tobin lists several types of "killer buildings" that would sustain the most damage in a California temblor, including older high rises and complexes featuring ground-floor parking:

* Most "tall, beautiful older buildings" built before 1980 that dot the San Francisco skyline were made without reinforcing steel, Tobin said.

* "Soft story" buildings with a ground-floor open garage or retail space also lack adequate bracing. The sturdier box of the upper floors likely would come crashing down on the "soft story."

* "Tilt up" buildings of concrete slab that are pushed upright to create a big box, such as for a grocery store, are among the most vulnerable. Some localities have mandated relatively low-cost reinforcement. Tobin says San Francisco has not.

* Unreinforced brick buildings would collapse easily.

...Frank Vernon, a geophysics professor and seismology specialist at the Scripps Institution of Oceanography at UC San Diego, described a similar fault far from San Francisco, hundreds of miles up the West Coast.

"The most important lesson in the U.S. and North America is the reminder that we have a similar subduction zone called Cascadia up on the coast of British Columbia, Washington, Oregon and very northern California which could do the same thing," he said.

"Some day we will be having this same type of earthquake near our shores," he said.