Time-dependent probabilistic tsunami risk assessment: application to Tofino, British Columbia, Canada, subjected to Cascadia subduction earthquakes

Katsuichiro Goda; Raffaele De Risi

doi:10.1038/s44304-024-00006-x

Time-dependent probabilistic tsunami risk assessment: application to Tofino, British Columbia, Canada, subjected to Cascadia subduction earthquakes

NPJ Nat Hazards. 2024;1(1):7. doi: 10.1038/s44304-024-00006-x. Epub 2024 May 7.

Authors

Katsuichiro Goda^{1

2}, Raffaele De Risi³

Affiliations

¹ Department of Earth Sciences, Western University, London, ON Canada.
² Department of Statistical & Actuarial Sciences, Western University, London, ON Canada.
³ Department of Civil Engineering, University of Bristol, Bristol, UK.

Abstract

A new time-dependent probabilistic tsunami risk model is developed to facilitate the long-term risk management strategies for coastal communities. The model incorporates the time-dependency of earthquake occurrence and considers numerous heterogeneous slip distributions via a stochastic source modeling approach. Tidal level effects are examined by considering different baseline sea levels. The model is applied to Tofino, British Columbia, Canada within the Cascadia subduction zone. High-resolution topography and high-quality exposure data are utilized to accurately evaluate tsunami damage and economic loss to buildings. The results are tsunami loss curves accounting for different elapsed times since the last major event. The evolutionary aspects of Tofino's time-dependent tsunami risk profiles show that the current tsunami risk is lower than the tsunami risk based on the conventional time-independent Poisson occurrence model. In contrast, the future tsunami risk in 2100 will exceed the time-independent tsunami risk estimate.

Keywords: Natural hazards; Ocean sciences; Solid Earth sciences.