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Empirical Calibration of Site Amplification From Residual Analysis of Earthquake Ground Motion Spectra and Station Magnitudes in Eastern Canada

Description: 

In this study, we find that local site amplification of short-period seismic waves are large sources of variability in the mean station magnitude residuals and ground motion intensity estimates needed for accurate earthquake monitoring and hazard mitigation. The adoption of ground motion models (GMMs) that account for source, path and site variability are important to consider for accurate Earthquake Early Warning (EEW) alerting. For periods in the range 0.02-10 seconds, we find that instrumentally observed ground motion intensity parameters are amplified by as much as 8-10 at some seismic stations located in glaciated regions of eastern Canada. Glaciation left many high seismic velocity, low attenuation shield rock sites exposed but where glacial sediments overlay the rock, high impedance contrast conditions exist. Such sharp impedance contrasts result in resonant effects that amplify short-period seismic energy, which has implications for EEW alerting systems in zones of high population density and critical infrastructure in eastern Canada. Using instrumentally observed New Generation Attenuation East (NGA-East) ground motions, we develop a log-linear relationship between seismic station site amplification and station magnitude residual (Mw). In addition, horizontal-to-vertical spectral ratio (HVSR) from microtremor are used to determine fundamental site period at the same sites. The comparison of HVSR site period to that obtained using NGAE-GMM earthquake spectral ratios provides proxy relationships between station-based magnitude, amplification and site period that should be implemented in EEW alerting systems in eastern Canada for improved accuracy of the predicted shaking.

Session: Earthquake Early Warning Optimization and Efficacy [Poster]

Type: Poster

Date: 4/20/2023

Presentation Time: 08:00 AM (local time)

Presenting Author: H K Claire Perry

Student Presenter: No

Invited Presentation: 

Authors