risparmier
Forumer storico
Mon Mar 14, 2011 9:47pm EDT
Forecasters in 2008 saw a 99 percent chance of a 6.7 magnitude quake within three decades, and 46 percent chance of a 7.5 or greater, with Southern California the likely center.
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."
....
Special report: Big California quake likely to devastate state | Reuters
Forecasters in 2008 saw a 99 percent chance of a 6.7 magnitude quake within three decades, and 46 percent chance of a 7.5 or greater, with Southern California the likely center.
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."
....
Special report: Big California quake likely to devastate state | Reuters
