SAN FRANCISCO — New research on earthquakes presented this week to mark the 100th anniversary of this city's great quake paints a disquieting picture of California's preparedness for a major temblor.
The overarching message of scientists gathered here was twofold. First, future quakes could easily do more damage than past ones because the population of California continues to increase and there are more buildings in areas near fault lines on soft ground susceptible to liquefaction. Second, the state must do more to retrofit vulnerable buildings.
A landmark study presented Thursday by noted structural engineer Charles Kircher found that 5% of buildings would cause 50% of the deaths in the event of a major temblor.
Earthquake cost: An article in Friday's California section said the estimated cost of a repeat of the 1906 San Francisco earthquake was $1.5 trillion. The correct amount is $150 billion.
Those buildings include unreinforced masonry, brittle concrete structures and buildings with open floor plans on the first floor, such as apartments with first-story garages or retail businesses.
Seismologists and state officials have long warned of the danger of such buildings, but regulating them has been difficult. Though some retrofitting has occurred on old brick buildings, relatively little has been done about so-called "nonductile" concrete buildings and "soft" first-story buildings despite their proliferation across the state.
Kircher's research is considered significant because it pulled together several disciplines.
He determined damage estimates by studying areas that earthquake waves would strike if the 1906 temblor occurred now, and then cross-referencing that data with information on where vulnerable buildings are located. Those facts then were combined with insurance industry estimates on the cost of replacing buildings and census data on how many people lived there.
Kircher said that unless thousands of buildings are upgraded to meet the newest earthquake standards, as many as 3,400 people could die if a magnitude 7.9 quake struck Northern California. That's more than twice the number of deaths caused by last year's hurricanes Katrina and Rita combined.
There would be $1.5 trillion worth of damage to buildings and property -- far more than the $125 billion estimated so far for the two hurricanes -- and up to 13,000 people would require hospitalization, his study found.
Kircher spoke at the first ever convocation of scientists, engineers, disaster preparedness officials and politicians that met in San Francisco this week to commemorate the 1906 temblor.
