Earthquake Risk Map

Hooray for the State Division of Mines and Geology (“A New Look at a State of Risk,” Science File, Dec. 19). Officials have finally acknowledged the true and significant earthquake risk that so many Californians live with every day. The next step now is to make the Structural Engineers Assn. look at this map and revise seismic design procedures to deal with this threat.

The current practice of structural engineers is to design buildings to only resist the minimum earthquake forces described in the 1994 Uniform Building Code, which are less than 40% of gravity (0.4g). These minimum forces contrast dramatically with this latest released map of risk, which shows many areas of California exposed to the threat of maximum shaking in excess of 60% (0.6g), as well as the intense shaking experienced near the epicenter of the Northridge earthquake, which was nearly equal to the full force of gravity (1.0g).

Unfortunately, the UBC is not intended to protect buildings from destruction or heavy damage--it is only intended to be a life safety code with the intent to allow people to escape before the building completely collapses.

It’s time to change the UBC so that owners must make the decision whether or not to spend additional money and build their buildings to withstand the risks shown on the seismic risk map. Structural engineers should not make these risk-based decisions--they probably won’t live in, sleep in, work in, or die in the buildings that they design with current minimum UBC design standards.

DAN FEGER

Northridge

* The real story appears to be that tectonic plate shift has brought Los Angeles to a new location just north of Oxnard on your map.

JON BARTEL

Goleta