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Show Earthquake Zone 4 rating change for Utah rejected By PAUL CHALLIS News Editor BOUNTIFUL The International Committee of Building Officials (ICBO) has rejected a proposal to give the Wasatch Front the highest seismic zone rating following unexpected opposition from local experts. The decision was made at the international conference con-ference on earthquakes held over the weekend (Feb. 8) in Indianapolis. The Lateral Design Committee heard five experts during the hearing with only one speaking in favor of the new Zone 4 plan, which would have put Utah's metropolitan area in the same category as the most seismically active areas of California, Alaska and Yellowstone National Park. Carl Eriksson, chairman of the state seismic advisory committee that recommended the reclassification, said the opposition came from officials who had formerly been neutral and from those who had been proponents of the proposal. According to Eriksson, all six members of the Lateral Lat-eral Design Committee voted against the reclassification, reclassifica-tion, citing the local dissent as one of the determining factors. Eriksson was the only expert to speak in favor of the change to enhance earthquake safety. Building trades representatives and a spokesman for the formerly neutral Utah Chapter of the ICBO, whose letter of opposition came as a surprise at the hearing, spoke against the reclassification. The proposed reclassification has received support during a series of public hearings held in Utah during 1991. If the higher rating had been adopted, the reclassification along with its more stringent design and construction standards would have been included in the 1994-95 Uniform Building Code. Ogden architect Thair H. Blackburn, who was one of the several unexpected witnesses to appear before the ICBO committee, claims the evidence is too inconclusive in-conclusive to justify the imposition of the higher construction con-struction standards and costs. Blackburn submitted a pamphlet to the committee in advance of the hearing claiming the seismicity studies show that Zone 4 areas in California are 1,000 times more active than the Wasatch Front. He also argued that the increased costs in a Zone 4 are not offset by the increased level of safety. Blackburn also claims that constructed buildings to fa meet the higher standards would provide an additional life-saving advantage of only 1 percent and that the new classification would also decrease property values across the board. Eriksson, a structural engineer and manager of Salt Lake County's inspection services, said the change would have had a minimal impact on new construction costs and would not have affected existing structures. He also discounted the property devaluation theory. Proponents have the option of challenging the committee's com-mittee's decision before the full ICBO in September, but officials doubt that will happen. The Wasatch Front is currently Zone 3 and if the Zone 4 had been adopted, the change, along with all of '. its design and construction requirements and perhaps ; higher costs, would have been inserted into the Uniform Building Code. Proponents of the proposal said the scientific ; evidence demand the higher rating to ensure the safety of the more than one million people who live and work along the Wasatch Front. ; Davis County is in the Salt Lake-Weber segment of the Wasatch Fault and is very earthquake prone, accor- ; ding to Sgt. Roger B. Anderson, coordinator for the ; Davis County Emergency Services. ! " It has been nearly 400 years since the last big quake hit the Wasatch Front. A 7.5 magnitude quake or ; greater is expected," he said ', Anderson is very concerned about all of the houses built on or near the fault line that runs right through Bountiful foothills from Beck Street to Centerville and ! then follows U.S. 89 from Farmington, Kaysville to Layton. The state Uniform Building Code Commission has ! asked the International Conference of Building Offi- cials to include the Wasatch Front area from Lev an in ! Juab County on the side to Brigham City on the north in ) Zone 4 classification. The decision to seek Zone 4 classification was '. spurred largely by a federal earthquake study involving Utah. The study ran from 1983 to 1988 and provided some surprising seismic data, according to the Utah ', Geological and Mineral Survey. Geologists say that state-of-the-art studies have ' shown there is the potential for much higher ground motion during an earthquake along the Wasatch Fault than previously expected, and the ground shaking is the cause of most damage to buildings during an earthquake. |