Minutes after a powerful 9.0 magnitude earthquake strikes off the coast of Vancouver Island during the summer, a devastating scenario unfolds in British Columbia. Thousands of residents are either killed or injured in the immediate aftermath, followed by a series of calamities including a tsunami, aftershocks, and widespread chaos. Overwhelmed survivors flood hospitals in search of their loved ones, while essential infrastructure such as roads and railways are severely damaged by the quake and subsequently flooded by the tsunami.
The B.C. government’s risk analysis paints a grim picture, projecting more than 3,400 fatalities and over 10,000 injuries on the day of the primary earthquake event. The repercussions extend beyond the initial shock, with additional casualties and destruction caused by subsequent hazards like aftershocks and fires. The report estimates a staggering cost of $128 billion, along with the destruction of 18,000 buildings and significant damage to another 10,000 structures. The economic fallout includes a halving of growth, leading to substantial GDP and job losses over the following decade, surpassing the cumulative impacts of all historical disasters in the region over the past two centuries.
The analysis highlights Vancouver Island and a 20-kilometre coastal stretch from the U.S. border to the Sunshine Coast, including Vancouver, as particularly vulnerable to the most severe damage. This assessment is part of the broader B.C. disaster and climate risk evaluation, dated October 2025, which outlines various extreme event scenarios such as severe flooding in the Fraser Valley, high-tide flooding following winter storms, urban interface fires, and prolonged droughts.
According to Edwin Nissen, a professor of earth and ocean sciences at the University of Victoria, the report’s predictions regarding fatalities and building destruction are based on detailed simulations. Nissen emphasizes the significance of factors such as the type of structure, its location, materials, and adherence to building codes in determining vulnerability to seismic activity. He underscores the uncertainty inherent in such forecasts, pointing out that variables like the time of day and year can significantly impact the outcome of a seismic event.
The report cites historical accounts of a comparable earthquake in 1700, derived from indigenous oral traditions and modern scientific investigations of the Cascadia fault line spanning 1,000 kilometers from Vancouver to Northern California. It assigns a probability range of two to ten percent for a similar catastrophic event occurring within the next three decades, drawing parallels to the 9.1-magnitude Indian Ocean earthquake in 2004 in terms of tectonic characteristics and tsunami generation.
Nissen stresses the irregularity of mega-quakes, emphasizing that they do not follow a predictable pattern and could occur sporadically. He advocates for ongoing preparedness efforts, given the unpredictable nature of seismic events and the potential for significant devastation. Despite the challenges in monitoring the Cascadia subduction zone due to limited seismic activity, Nissen underscores the importance of readiness and vigilance in the face of potential catastrophic events.