Earthquake Ground Motion and 3D Georgia Basin Amplification in Southwest British Columbia: Deep Juan de Fuca Plate Scenario Earthquakes

Molnar, Sheri; Cassidy, John F.; Olsen, Kim B.; Dosso, Stan E.; He, Jiangheng

doi:10.1785/0120110277

Cited by 16 publications

(35 citation statements)

References 92 publications

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“…SEM is very effective at achieving high accuracy even for realistic earth models, and is therefore applicable for a wide range of applications in seismology (Komatitsch & Vilotte [16]). This approach to scenario ground modelling is similar to that used by Molnar et al [40] and Molnar et al [41] to study seismic wave interaction with 3D structure of the Georgia Basin, British Columbia, Canada.…”

Section: Numerical Simulation Of Seismic Wavesmentioning

confidence: 99%

Basin Resonance and Seismic Hazard in Jakarta, Indonesia

et al. 2018

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Abstract:We use earthquake ground motion modelling via Ground Motion Prediction Equations (GMPEs) and numerical simulation of seismic waves to consider the effects of site amplification and basin resonance in Jakarta, the capital city of Indonesia. While spectral accelerations at short periods are sensitive to near-surface conditions (i.e., V S30 , average shear-wave velocity at topmost 30 m of soil), our results suggest that, for basins as deep as Jakarta's, available GMPEs cannot be relied on to accurately estimate the effect of basin depth on ground motions at long periods (>3 s). Amplitudes at such long periods are influenced by trapping of seismic waves in the basin, resulting in longer duration of strong ground motion, and interference between incoming and reflected waves as well as focusing at basin edges may amplify seismic waves. In order to simulate such phenomena in detail, a basin model derived from a previous study is used as a computational domain for deterministic earthquake scenario modeling in a 2-dimensional cross-section. A M w 9.0 megathrust, a M w 6.5 crustal thrust and a M w 7.0 intraslab earthquake are chosen as scenario events that pose credible threats to Jakarta, and the interactions with the basin of seismic waves generated by these events were simulated. The highest long-period PGVs amplifications are recorded at sites near the middle of the basin and near its southern edge, with maximum amplifications of PGV in the horizontal component of 726% for the crustal, 1500% for the megathrust and 1125% for the deep intraslab earthquake scenario, respectively. We find that the levels of response spectral acceleration fall below those of the 2012 Indonesian building Codes's design response spectra for short periods (<1 s), but closely approach or may even exceed these levels for longer periods.

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Section: Numerical Simulation Of Seismic Wavesmentioning

confidence: 99%

Basin Resonance and Seismic Hazard in Jakarta, Indonesia

et al. 2018

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“…This paper presents finite-difference (FD) simulations of long-period (> 2 s) ground motions computed for M w 6.8 shallow North America (NA) plate scenario earthquakes in southwest British Columbia in a regional 3D velocity model of the Georgia basin; Molnar et al (2014), deals with deep (42-55 km) subducting Juan de Fuca (JdF) plate scenario earthquakes. The main objective in this study and in Molnar et al (2014), is to examine the effect of 3D Georgia basin structure on predicted ground shaking across Greater Vancouver from large (M w 6.8) scenario earthquakes.…”

Section: Introductionmentioning

confidence: 99%

“…The main objective in this study and in Molnar et al (2014), is to examine the effect of 3D Georgia basin structure on predicted ground shaking across Greater Vancouver from large (M w 6.8) scenario earthquakes.…”

Section: Introductionmentioning

confidence: 99%

“…2) and a chosen kinematic rupture model of the 1994 M w 6.7 Northridge, California, blind-thrust earthquake, respectively. As in Molnar et al (2014), a single source rupture model is used to simulate all scenario earthquakes; hence, the results presented here are limited to the single set of blind-thrust rupture characteristics chosen here. Scenario blind-thrust earthquakes are simulated in different locations in the Georgia basin region, congruent with known seismicity and within 100 km of Vancouver, to investigate variation in the strength of predicted ground motions and 3D basin effects.…”

Section: Introductionmentioning

confidence: 99%

“…Scenario blind-thrust earthquakes are simulated in different locations in the Georgia basin region, congruent with known seismicity and within 100 km of Vancouver, to investigate variation in the strength of predicted ground motions and 3D basin effects. The finite-difference scheme and 3D physical-structure models are described in Molnar et al (2014). As in Molnar et al (2014), the chosen peak ground velocity (PGV) metric is the geometric mean of the orthogonal horizontal components, calculated as max t v EW t × v NS t p , in which vt represents a synthetic horizontal velocity waveform, EW represents east-west component, and NS represents north-south component.…”

Section: Introductionmentioning

confidence: 99%

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Earthquake Ground Motion and 3D Georgia Basin Amplification in Southwest British Columbia: Shallow Blind-Thrust Scenario Earthquakes

Molnar

Cassidy

Olsen

et al. 2014

Bulletin of the Seismological Society of America

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Finite-difference modeling of 3D long-period (> 2 s) ground motions for large (M w 6.8) scenario earthquakes is conducted to investigate the effects of the Georgia basin structure on ground shaking in Greater Vancouver, British Columbia, Canada. Scenario earthquakes include shallow blind-thrust North America (NA) plate earthquakes, simulated in locations congruent with linear clusters of shallow seismicity, that is, potential active faults. A slip distribution model of the M w 6.7 Northridge, California, blind-thrust earthquake, with the hypocenter modified to 5 km depth, is used to characterize the source rupture process. Two sets of simulations are performed for a given scenario earthquake using models with and without Georgia basin sediments. The ratio of predicted peak ground velocity (PGV) for the two simulations is applied here as a quantitative measure of amplification due to 3D basin structure.

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Impacts of simulated M9 Cascadia Subduction Zone earthquakes considering amplifications due to the Georgia sedimentary basin on reinforced concrete shear wall buildings

Kakoty

Dyaga

Hutt

2020

Earthq Engng Struct Dyn

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Southwest British Columbia has the potential to experience large-magnitude earthquakes generated by the Cascadia Subduction Zone (CSZ). Buildings in Metro Vancouver are particularly vulnerable to these earthquakes because the region lies above the Georgia sedimentary basin, which can amplify the intensity of ground motions, particularly at medium-to-long periods. Earthquake design provisions in Canada neglect basin amplification and the consequences of accounting for these effects are uncertain. By leveraging a suite of physicsbased simulations of M9 CSZ earthquakes, we develop site-specific and perioddependent spectral acceleration basin amplification factors throughout Metro Vancouver. The M9 simulations, which explicitly account for basin amplification for periods greater than 1s, are benchmarked against the 2016 BC Hydro ground motion model (GMM), which neglects such effects. Outside the basin, empirical and simulated seismic hazard estimates are consistent. However, for sites within the basin and periods in the 1-5 s range, GMMs significantly underestimate the hazard. The proposed basin amplification factors vary as a function of basin depth, reaching a geometric mean value as high as 4.5 at a 2-s period, with respect to a reference site located just outside the basin. We evaluate the impact of the M9 simulations on tall reinforced concrete shear wall buildings, which are predominant in the region, by developing a suite of idealized structural systems that capture the strength and ductility intended by historical seismic design provisions in Canada. Ductility demands and collapse risk conditioned on the occurrence of the M9 simulations were found to exceed those associated with ground motion shaking intensities corresponding to the 975 and 2475-year return periods, far exceeding the ∼500-year return period of M9 CSZ earthquakes.

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Earthquake Ground Motion and 3D Georgia Basin Amplification in Southwest British Columbia: Deep Juan de Fuca Plate Scenario Earthquakes

Cited by 16 publications

References 92 publications

Basin Resonance and Seismic Hazard in Jakarta, Indonesia

Basin Resonance and Seismic Hazard in Jakarta, Indonesia

Earthquake Ground Motion and 3D Georgia Basin Amplification in Southwest British Columbia: Shallow Blind-Thrust Scenario Earthquakes

Impacts of simulated M9 Cascadia Subduction Zone earthquakes considering amplifications due to the Georgia sedimentary basin on reinforced concrete shear wall buildings

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