Analysis of Strong-Motion Data from the Mount Borah, Idaho, Earthquake of 28 October 1983

摘要

An analysis was made of the strong-motion data from the Mount Borah, Idaho, earthquake of 28 October 1983, which occurred at latitude 44.046 N, 113.887 W and had a surface wave magnitude M sub s of 7.3. Twenty-seven accelerograms recorded at Ririe, Lucky Peak, and Dworshak Dams were digitized. The raw digitized accelerograms were processed to provide baseline correction. Integrals and shock spectra are presented in graphic form. Based on the statistical analysis of the peak ground motions, acceleration (a), velocity (v), and displacement (d), it has been found that the average ratios of v/a , a sub v over a sub h (vertical maximum acceleration to horizontal maximum acceleration), and ad over v squared are 0.089 sec, 0.58, and 3.17, respectively. The epicentral distances to Ririe and Lucky Peaks Dam are about the same (180 km). The amplification ratios of maximum accelerations on the crest to the maximum accelerationa at the abutment for Lucky Peak Dam are 5.69, 4.01, and 3.76 for longitudinal (L), vertical (V), and transverse (T) components, respectively. However, the ratios of the two dams are believed due to the different dam heights: 104 m for Lucky Peak Dam and 41.5 m for Ririe Dam. The data from Dworshak Dam, A concrete structure, are not appropriate for comparison with data from the other two dams, which are earth and rock-fill structures.