Using new tools that make it easier to assess potential levels of damage resulting from earthquakes, University of Illinois professor Robert Olshansky and graduate student Yueming Wu have been able to assign a dollar amount to that risk. They determined that the average annual direct cost of earthquakes in Los Angeles County, based on actual structural and nonstructural damage to buildings alone, is $388 million.
"If it were not already clear that earthquakes are a significant long-term problem in Los Angeles County, this number certainly makes that point," said Olshansky, a professor of urban and regional planning. In addition, he said, the pair estimated that planned growth of 14.2 percent in the region would result in an increase in annual risk to $449.5 million, a 15.8 percent increase over the risk to current land uses. The projections were included in a study published recently in the journal Environment and Planning B: Planning and Design.
Olshansky and Wu arrived at their conclusions using a hazard assessment model known as risk analysis. "Local governments almost never use risk analysis, the most sophisticated level of hazard assessment, to inform their planning and development decisions," Olshansky said. "But new tools are rapidly becoming available to accomplish such analysis." Olshansky and Wu used available land-use maps, a probabilistic earthquake hazard model for the area, and the Federal Emergency Management Agency’s new HAZUS earthquake loss-estimation software to prepare their report.
Olshansky, who also published a report on "Land Use Planning for Seismic Safety: The Los Angeles County Experience, 1971-1994" in the spring issue of the Journal of the American Planning Association, emphasized that "the best way to reduce costs associated with earthquakes is building according to the latest seismic building codes."
Still, he said, "because of ever-increasing disaster costs, planners need to be able to evaluate the risks that their communities face, both in the present and in the future. It is particularly important for planners to be sure that they are not disproportionately planning future growth for hazardous locations." That’s a valid concern for Los Angeles County, where the highest seismic hazard is present in the northern region, an area that has experienced increasing suburban growth over the past decade.