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Hybrid Empirical Ground-Motion Models with Simulation-based Site Amplification Factors for the Island of Hawaii

Description: 

The primary purpose of this study is to develop Ground Motion Models (GMMs) with Site Amplification Factors for the island of Hawaii. We develop GMMs using the Hybrid Empirical Method (HEM) with a companion simulation-based Site Amplification Model for the V_S30 requirements of the National Seismic Hazard Mapping program (V_S30 is time-averaged shear wave velocity in the upper 30 m of the site). Stochastically simulated Ground Motion Intensity Measures (GMIMs) in the host and target regions are utilized in HEM to develop adjustment factors that are applied to empirical GMIM predictions in the host region. The island of Hawaii, the target region in this study, has been the site of numerous large earthquakes with a growing database of strong ground motion observations. The crustal earthquakes on the island of Hawaii originate from volcanic activity and include both swarms of small-magnitude volcanic events and larger tectonic events. Ground motion modeling on the island of Hawaii is challenging due to the depth distribution of events and different anelastic attenuation characteristics. In the absence of an amplification model for the island of Hawaii, the proposed simulation-based amplification model can be used not only for the proposed GMMs but for all other previously developed GMMs that will be considered in the upcoming national seismic hazard maps updates.
Since the hazard comes both from shallow crustal earthquakes and from deep events for the island of Hawaii, two separate GMMs are being developed. We consider the focal depth of 20 km to distinguish between shallow crustal and deep earthquakes. A moment magnitude range of 4.0 to 7.5 and Joyner-Boore distances of up to 400 km are considered. For the required seismological parameters in WNA, we use Zandieh et al. (2018) results. For the required seismological parameters in the island of Hawaii, we use Wong et al. (2020).

Session: USGS National Seismic Hazard Models: 2023 and Beyond [Poster]

Type: Poster

Date: 4/18/2023

Presentation Time: 08:00 AM (local time)

Presenting Author: Shahram Pezeshk

Student Presenter: No

Invited Presentation: 

Authors