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Regional Attenuation Estimates for California Using Coda Waves

Session: How Well Can We Assess Site Effects So Far? [Poster]

Type: Poster

Date: 4/21/2021

Presentation Time: 03:45 PM Pacific

Description: 

The effect of site conditions on the characteristics of ground motions is a complex function of several factors such as the stiffness and attenuation characteristics (both scattering and absorption) of local materials near the surface and at depth. Finding an effective proxy for site effects is necessary for the development of ground motion models and the assessment of site-specific seismic hazards. The high-frequency spectral decay parameter kappa has recently gained popularity in the aforementioned applications because its site-specific component, k₀,cancapture the near-surface attenuation at a site. The attenuation characteristics of reference rock sites are of particular interest in seismic hazard evaluations, but the lack of ground motion records at hard-rock sites makes the estimation of k0 from the classic Anderson and Hough (1984) approach (hereafter referred to as k0_AH) challenging. Recently, k0_coda values estimated from multiple-scattered coda waves were found to correlate well with k0 at hard rock sites in France, while highlighting regional variations. In this work, regional attenuation characteristics of hard-rock sites in California are analyzed through the lens of k0_coda. First, a catalog of ground motion records across the region is compiled, including motions from the recent Ridgecrest earthquake sequence. Then, k0_coda values are computed to evaluate hard-rock regional characteristics in the region. Additionally, the availability of multiple ground motions and site information in California offers a unique opportunity to validate the performance of k0_coda in the region via comparisons to classical k0_AH values.

Presenting Author: Chunyang Ji

Student Presenter: Yes

Authors