Ocean Sciences Meeting Report

Detecting Near-Field Tsunamis off the Coast of British Columbia

A Near-Field Tsunami Initiative for the Coast of British Columbia;
Port Alberni, British Columbia, 27–28 March 2014

By Tania Lado Insua and Kate Moran

Geological and historical records of the coast of British Columbia (BC) and orally transmitted legends from the First Nations in the area indicate the recurrence of tsunamis in this region. Recent studies show a 40% to 80% probability of a local earthquake occurring in the next 50 years over the Cascadia subduction zone, generating a tsunami run-up higher than 1.5 meters. Ocean Networks Canada (ONC) operates ocean observatories off the west coast of BC. Smart Oceans BC is a new multifaceted program to support coastal communities and decision makers by leveraging the unique capabilities of ONC’s advanced cabled ocean observatories to inform public safety, marine safety, and environmental monitoring.

In March 2014, ONC hosted a 2­-day international workshop on tsunami modeling and instrumentation. A total of 44 attendees from Canada, Japan, India, the United States, Germany, France, and Italy gathered in Port Alberni, BC, on the ­50-year anniversary of the tsunami that devastated this city following the 1964 Alaskan earthquake. They presented tsunami and geohazards research and discussed the design and technology that should be implemented for the detection and forecast of near-field tsunamis off the coast of British Columbia. They also indicated the need for more detailed bathymetry and topography, as well as a broader real-time network of instruments and detailed models.

Some instruments, such as bottom pressure recorders, strong motion sensors, hydrophones, and GPS systems, were recommended in particular configurations. Meeting participants raised questions about the accuracy of models for British Columbia based on the quality and coverage of current bathymetry and coastal topography.

Predictive modeling discussions focused on conducting a benchmark test among several models, such as ­Funwave and ­NHwave, to compare and exchange techniques using the same local case conditions, such as the 1964 Port Alberni tsunami. For this purpose, ONC will develop a model environment, using ONC bathymetry and data from network instruments, for evaluation and comparison of different computational models. The information available for fault mechanics, rupture scenarios, and real-time source definition is limited, and this gap affects modeling of tsunami sources, an essential first step in any tsunami forecast. More paleo­seismic evidence is necessary to have better knowledge of the sources.

Materials from this workshop, including videos and presentation slides, are available at http://www​.­oceannetworks​.ca/​­​­tsunami​-­workshop​-2014.

New funding from Western Economic Diversification Canada, along with collaborations and recommendations from the workshop, is currently driving the development of a new tsunami initiative and prototype for the coast of British Columbia.

We thank the mayor of Port Alberni, the Tseshaht Nation, Martin Heesemann, Steve Mihaly, and the attendees of the workshop.

 

—Tania Lado Insua and Kate Moran, Ocean Networks Canada, University of Victoria, Victoria, BC, Canada; ­email: [email protected]

© 2014. American Geophysical Union. All rights reserved.