A catastrophic 9.0 magnitude earthquake hits off Vancouver Island on a summer day, resulting in thousands of casualties. The aftermath includes a tsunami, aftershocks, and widespread devastation. Hospitals are overwhelmed with distraught survivors searching for their loved ones, while road and rail connections suffer severe damage and flooding. The B.C. government risk analysis predicts over 3,400 fatalities and 10,000 injuries on the day of the main quake, with additional casualties from subsequent hazards.
The estimated costs are staggering at $128 billion, with 18,000 buildings destroyed and 10,000 more severely damaged. Economic growth is halved, leading to significant GDP and job losses over the following decade. The impact is projected to surpass all previous disasters in B.C. history. The most severe damage is anticipated on Vancouver Island and a 20-kilometre coastal stretch from Vancouver to the Sunshine Coast.
This analysis is part of the B.C. disaster and climate risk assessment, dated October 2025, which outlines various extreme event scenarios. These include severe flooding in the Fraser Valley, high-tide flooding on the southwest coast post-winter storm, urban interface fires, and prolonged droughts.
Edwin Nissen, a professor of earth and ocean sciences at the University of Victoria, explained that the report’s casualty and building destruction estimates are based on simulations. Factors such as location, building material, and construction codes influence the structural integrity of homes during earthquakes. Wood-frame structures tend to fare better, while brick buildings are more vulnerable. Proximity to bedrock also plays a crucial role in determining safety levels.
Nissen emphasized the uncertainty surrounding the figures due to variables like the time and season of the earthquake. Winter earthquakes are particularly hazardous due to increased water saturation in the ground, leading to heightened risks of landslides and soil liquefaction. He highlighted the importance of regularly updating emergency reports to keep pace with evolving scientific and engineering knowledge.
The report cites the last comparable earthquake in the region occurring in 1700, with knowledge gathered from oral histories of First Nations and scientific studies of the Cascadia fault, spanning from mid-to-northern Vancouver to Northern California. The likelihood of a similar extreme event in the next 30 years is estimated between two to ten percent, with the 2004 Indian Ocean earthquake serving as a comparable reference point.
Despite the extended period since the last major earthquake, Nissen cautioned against assuming a regular pattern for such events. The unpredictable nature of seismic activity underscores the necessity for ongoing preparedness efforts. Cascadia’s relative seismic quietness poses challenges for scientists, underscoring the need for continued research and readiness for potential seismic events.