Geological-Seismological Evaluation of Earthquake Hazards for Appurtenant Structures at Gathright Dam, Virginia

Abstract : There are no active faults in the region surrounding Gathright Dam, though a notable earthquake occurred in Giles County about 60 km to the southwest. The Giles County source was interpreted to have a maximum potential of MM IX which attenuates to MM VII at the dam and is the severest event to be expected at that site. Peak horizontal motions at the damsite for a mean plus one standard deviation were interpreted as 130 cm/sec2 for acceleration, 14 cm/ sec for velocity, and 11 sec for bracketed duration equal to or greater than 0. 05 G. These values are for use as parameters in selecting or scaling accelerograms and response spectra for use in dynamic analyses. A recommended group of accelerograms are included in the report. (sdw)