1901-1919 N Fairview St - Soils Report

Home Browse Search

603284-001 The frequencies of exceedance of different values of peak ground and spectral accelerations at the site were calculated by combining the following probability functions: The annual frequency of earthquakes of various magnitudes on a fault obtained from the fault recurrence relationships; . Given an earthquake of a certain magnitude on a certain fault, the probability distribution of the location of the earthquake on the fault was obtained using the selected rupture area versus magnitude relationship and assuming equal likelihood of rupture along the length and some prescribed probabilities along the depth of the fault; and . Given an earthquake of a certain magnitude occurring at a certain distance from the site, the probability distribution of ground motion at the site was obtained from the selected attenuation relationships. The above process is repeated a sufficient number of times to cover all the sources, then summed to obtain the total seismic hazard at the site. This process results in a relationship between ground motion level and the probability of being exceeded. The computer program EZ-FRISK Version 7.60 Build 001 (Risk Engineering, Inc., 2011) for probabilistic seismic hazard analysis was utilized to perform the PSHA. Deterministic Seismic Hazard Analvsis (DSHA) The DSHA consists of a four-step process (Reiter, 1990): . Defining the location, geometry, and characteristics of earthquake sources relative to the site; . Determination of the site-to-source distance for each earthquake source defined relative to the site; Selection of the controlling earthquake relative to the site as defined by some ground motion parameter. The controlling earthquake is defined by the seismic scenario based on the above two steps that produces the largest magnitude of the ground motion parameter being used; and . Using the controlling earthquake, the ground motion at the site is obtained from the selected attenuation relationships. D-3