Seismic hazard evaluation for dams in northern Colorado, U.S.A.

✍ Scribed by Ute R. Vetter; Jon P. Ake; Roland C. Laforge

• Publisher: Springer Netherlands
• Year: 1997
• Tongue: English
• Weight: 824 KB
• Volume: 14
• Category: Article
• ISSN: 0921-030X
• DOI: 10.1007/bf00128268

✦ Synopsis

A seismic hazard evaluation for three dams in the Rocky Mountains of northern Colorado is based on a study of the historical seismicity. To model earthquake occurrence as a random process utilizing a maximum likelihood method, the catalog must exhibit random space-time characteristics. This was achieved using a declustering procedure and correction for completeness of recording. On the basis of the resulting a-and b-values, probabilistic epicentral distances for a 2 x 10 -5 annual probability were calculated. For a random earthquake of magnitude ML 6.0-6.5, this distance is 15 kin. Suggested ground motion parameters were estimated using a probabilistie seismic hazard analysis. Critical peak horizontal accelerations at the dams are 0.229 if median values are assumed and 0.399 if variable attenuation and seismicity rates are taken into account. For structural analysis of the dams, synthetic acceleration time series were calculated to match the empirical response spectra. In addition, existing horizontal strong motion records from two Mammoth Lakes, California earthquakes were selected and scaled to fit the target horizontal acceleration response spectra.