Assessing components of ground-motion variability from simulations for the Marmara Sea region (Turkey)

Douglas, John and Aochi, Hideo (2016) Assessing components of ground-motion variability from simulations for the Marmara Sea region (Turkey). Bulletin of the Seismological Society of America, 106 (1). pp. 300-306. ISSN 0037-1106 (https://doi.org/10.1785/0120150177)

[thumbnail of Douglas-Aochi-BSSA-2015-Assessing-components-of-ground-motion-variability-from-simulations]
Preview
 Text. Filename: Douglas_Aochi_BSSA_2015_Assessing_components_of_ground_motion_variability_from_simulations.pdf
Accepted Author Manuscript
Download (1MB)| Preview

Abstract

Recent studies have shown that repeatable travel-path terms make a high contribution to the overall variability in earthquake ground motions. Having maps of such terms available for a given recording site would, theoretically, allow removal of this component from the aleatory variability of ground-motion models. The assessment of such travel path terms for a given site, however, relies on having recorded a rich set of earthquakes at that site. Given the relative youth of strong-motion networks the assessment of such terms from observations is currently difficult for most parts of the world. Ground-motion simulations, however, provide an alternative method to assess such terms. In this article many dozens of earthquakes, distributed in a grid, are simulated for the Marmara Sea region (Turkey), which borders the megacity of Istanbul and is an area of high seismic hazard. Ground motions are simulated within a detailed 3D velocity structure model using a finite-difference method at 70 recording sites in the area (200 x 120km). Horizontal peak ground velocities from these simulations are regressed to derive a ground-motion model. Next, residuals from these GMPEs are computed to assess repeatable source, site and path terms and various components of ground-motion variability. These components are similar to those derived from real strong-motion data, thereby lending support to those estimates as well as showing the worth of simulations for this type of exercise.

CORE (COnnecting REpositories)