Experts Warn of Stronger Quakes in State : Safety: One calls Jan. 17 temblor ‘a near miss’ for L.A.’s high-rise buildings. Seismic Safety Commission meets today.

On the eve of a state Seismic Safety Commission report to the governor on construction safeguards in the wake of the Northridge earthquake, several leading scientists reiterated warnings Wednesday that stronger temblors will occur in California.

In a pointed message delivered at the fall meeting of the American Geophysical Union, Tom Heaton of the Pasadena field office of the U.S. Geological Survey said the Northridge quake had represented “a near miss” for Los Angeles’ high-rise buildings.

Heaton said state authorities should be aware that the strongest shaking Jan. 17 was under the Santa Susana Mountains, “where the tall buildings weren’t.” He said it is highly likely that there will be quakes in the Los Angeles Basin that will be stronger, last longer and be even more centrally located.

The seismologist noted that cracks had appeared in steel-framed buildings in the Northridge earthquake, and suggested that construction codes be strengthened.

Immediately after Heaton’s remarks, another scientist, Caltech’s Egill Hauksson, expressed concern that the building code standards recommended in the upcoming Seismic Safety Commission report may not be strong enough to weather major quakes.

The commission meets in Sacramento today. Its report to Gov. Pete Wilson is more than three months late. At a meeting last month, members suggested that they might not recommend certain revisions of state building codes that they thought might be too costly. Regardless of those recommendations, scientists here Wednesday said that there is a definite prospect of larger and possibly more frequent earthquakes in the urban areas of Southern California and the San Francisco Bay Area, where the damage would be heavy.

James F. Dolan of Caltech noted that studies of past quake records indicate that there have been fewer quakes in the last century than would normally be expected in the Los Angeles area.

It could be that big quakes either come in clusters, or that Southern California is in a “centuries-long interseismic period between much larger, less frequent events,” Dolan said.

His data suggests that there have been no quakes between magnitude 7.2 and 7.6 generated within the Los Angeles metropolitan area since 1800, when record keeping began.

Jim Mori, the scientist in charge of the Geological Survey’s Pasadena office, estimated that a Northridge-size earthquake, now measured at magnitude 6.7, might occur in the Los Angeles region about once every 40 years.

Magnitude 7 earthquakes are to be expected in the Los Angeles Basin, he said, and the motions generated from them could put dangerous strains on high-rise buildings if they were centered in built-up areas.

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