The “Analogous Region Approach” – a New Approach to Defining Earthquake Recurrence Parameters in Regions of Low or Incomplete Earthquake Occurrence

Date: 4/25/2019

Time: 06:00 PM

Room: Grand Ballroom

Estimating site-specific earthquake ground motions for seismic design of critical facilities requires the identification and characterization of regional earthquake sources that will contribute to the hazard at the site. Seismic source characterization is a complex process that requires defining earthquake recurrence parameters for each seismic source from the historical and instrumental earthquake record. While the earthquake recurrence estimation procedures are relatively well established for areas of high seismicity, regions with an incomplete earthquake record or low earthquake occurrence rate are very difficult to reliably characterize.

The “Analogous Region Approach” (ARA) has been proposed as a method to improve the definition of earthquake recurrence parameters in regions of low seismicity. The goal of the ARA is to identify and adopt acceptable earthquake recurrence parameters (i.e., a- and b- values in the Gutenberg Richter equation) that can support seismic design of critical structures. The ARA is based on the identification and selection of analogous tectonic regions with similar tectonic characteristics as the seismic source zones surrounding the site of interest.

The ARA is used to validate, and where necessary, calibrate the earthquake recurrence parameters used for probabilistic and deterministic seismic hazard analyses in seismic quiescence regions. This ARA also allows definition of “preferred values” and the upper-lower bounds for the earthquake recurrence parameters used in the logic tree approach to capture the epistemic uncertainties in probabilistic modeling.

Application of the ARA allowed to develop site-specific seismotectonic models for relatively seismic-inactive and quiescent regions. Testing of the results developed from application of the ARA have shown good agreement with the results of similar studies available in the published literature and for site-specific studies undertaken by others.

Presenting Author: Alan G. Hull

Authors