Prompt Tsunami Loss Estimation Using Satellite Imagery

This study explores the development of prompt tsunami loss estimation methods that are based on inundation hazard parameters inferred from remotely-sensed images. Using a tsunami catastrophe model for the Tohoku region of Japan, approximate tsunami loss functions are derived for coastal communities in Miyagi Prefecture. Calibration of the prompt tsunami loss estimation models is carried out by utilizing predicted tsunami losses for 4000 stochastic earthquake scenarios of moment magnitudes between Mw7.5 and Mw9.1. Using numerous earthquake sources facilitates the robust calibration of the developed tsunami loss functions. Special considerations are given to investigate the effects of coastal topography and the potential bias due to errors in estimating inundation parameters.This work is supported by the Leverhulme Trust (RPG-2017-006) and the Canada Research Chair in Multi-Hazard Risk Assessment program at Western University (950-232015)

Spatiotemporal Seismic Risk Assessment of Wood-frame Houses in Victoria, Canada under M9 Megathrust Subduction Sequences

This study assesses spatiotemporal seismic risk of a realistic portfolio of wood-frame houses in the City of Victoria, British Colombia, Canada, subjected to a M9 sequence of earthquakes originating from the Cascadia subduction zone in Pacific Northwest. Crustal aftershocks, triggered by the mega-thrust mainshock, may occur in much proximity to population and buildings, and different types of buildings may be affected due to different ground-motion characteristics. The developed time-dependent seismic risk model consists of an Epidemic Type Aftershock Sequence model, ground-motion model, and aftershock seismic fragility model. The seismic hazard model for synthetic mainshock-aftershock sequences is combined with the state-dependent fragility model to estimate time-dependent damage states of wood-frame houses. The output of the assessment is useful for making various risk management decisions more effectively.This work is supported by the Leverhulme Trust (RPG-2017-006) and the Canada Research Chair in Multi-Hazard Risk Assessment program at Western University (950-232015)

A New Tsunami Hazard Assessment for Eastern Makran Subduction Zone by Considering Splay Faults and Applying Stochastic Modeling

Tsunami hazard imposed by possible rupture of splay faults is important as it may significantly intensify tsunami heights locally. The Makran Subduction Zone (MSZ) in the northwestern Indian Ocean can generate large thrust earthquakes that could trigger significant tsunamis. In this paper, the effects of possible rupture of splay faults on the tsunami hazards of eastern MSZ are studied by developing a framework that uses stochastic earthquake rupture models and considers uncertainties related to rupture location, rupture geometry, seismic moment split ratio, earthquake slip asperity location within a fault plane, and earthquake slip heterogeneity. To quantify these uncertainties, 484 different parameter combinations of tsunami sources are considered systematically. The geometry of splay faults is developed using the most recent marine seismic surveys of the tectonic structure of the MSZ. A moment magnitude of 8.6 is considered as a scenario magnitude. The results of this study are generated in two parts, by considering average sources and stochastic sources. Results show significant local amplification of the maximum tsunami heights due to splay faults. For instance, the maximum wave height in Pasni, Pakistan can be amplified by a factor of four due to a single splay fault rupture scenario of average sources.</p

Stochastic coupled simulation of strong motion and tsunami for the 2011 Tohoku, Japan earthquake

© 2016 The Author(s)This study conducts coupled simulation of strong motion and tsunami using stochastically generated earthquake source models. It is focused upon the 2011 Tohoku, Japan earthquake. The ground motion time-histories are simulated using the multiple-event stochastic finite-fault method, which takes into account multiple local rupture processes in strong motion generation areas. For tsunami simulation, multiple realizations of wave profiles are generated by evaluating nonlinear shallow water equations with run-up. Key objectives of this research are: (i) to investigate the sensitivity of strong motion and tsunami hazard parameters to asperities and strong motion generation areas, and (ii) to quantify the spatial variability and dependency of strong motion and tsunami predictions due to common earthquake sources. The investigations provide valuable insights in understanding the temporal and spatial impact of cascading earthquake hazards. Importantly, the study also develops an integrated strong motion and tsunami simulator, which is capable of capturing earthquake source uncertainty. Such an advanced numerical tool is necessary for assessing the performance of buildings and infrastructure that are subjected to cascading earthquake–tsunami hazards