Volcanology of Canada - Mitigation and Vulnerability

Mitigation and Vulnerability

In Canada, even though volcanoes pose significant threats to local communities and any sizable eruption would affect Canada's economy, the work of understanding the frequency and eruption characteristics at volcanoes in Canada is a slow process. This is because most of Canada's dormant and potentially active volcanoes are located in isolated jagged regions, very few scientists study Canadian volcanoes and the provision of money in the Canadian government is limited. Because of these issues, scientists studying Canada's volcanoes have a basic understanding of Canada's volcanic heritage and how it might impact people in the future. Volcanologists are aware that certain areas in Canada have higher levels of volcanic activity than others and how eruptions in these areas might affect people and the environment they live in. When a volcano is showing evidence of volcanic activity, quick action will be required to better understand the process. The lowest possibility for an eruption in Canada per year is approximately 1/200; for a passive lava eruption the possibility is about 1/220, and for a major explosive eruption it is about 1/3333. Even though volcanoes do not seem to be part of the everyday reality of Canadians, recurrent earthquakes and the formation of large mountain ranges in the Pacific Northwest indicate this part of Canada is still geologically active. The possibility of an eruption, even a large explosive one, cannot be ruled out. Quiet as they currently seem, volcanoes in Northern and Western Canada are part of the Pacific Ring of Fire. Along with volcanoes associated with recent earthquake activity, a scenario of an eruption at Mount Cayley in southwestern British Columbia illustrates how Western Canada is in danger to a volcanic eruption, which has not erupted for at least 310,000 years. This impact is becoming even more likely as population in the Pacific Northwest increases and development spreads. The scenario is based on former eruptions in the north-south trending Garibaldi Volcanic Belt and includes both explosive and passive eruptions. Its effect is mostly due to the attention of defenseless public services in canyons. However, the threat from volcanoes outside of Canada seems much greater than the threat from volcanoes within Canada because of the lack of monitoring data at Canadian volcanoes and the age of most volcanoes in Canada is poorly known. But for some, their minimal degree of erosion indicates they formed much less than 10,000 years ago, including the Milbanke Sound Group on Price Island, Dufferin Island, Swindle Island, Lake Island, and Lady Douglas Island in the Milbanke Sound area of coastal British Columbia. However, it is known volcanoes in the U.S. states of Alaska, Washington, Oregon and California have been more active in historic times than those within Canada. Therefore volcanoes in the United States are monitored with caution and attention by the United States Geological Survey.

Growing awareness of volcanism, especially the threat from volcanoes in the United States, has led to a number of changes in the way Canadians are dealing with volcanic hazards. For example, The Barrier, an unstable lava dam retaining the Garibaldi Lake system of southwestern British Columbia, has in the past unleashed several debris flows, most recently in 1855–1856. This led to the evacuation of the small resort village of Garibaldi nearby and the relocation of residents to new recreational subdivisions away from the hazard zone. Should The Barrier completely collapse, Garibaldi Lake would be entirely released and downstream damage in the Cheakamus and Squamish rivers would be considerable, including major damage to the town of Squamish and possibly an impact-wave on the waters of Howe Sound that would reach Vancouver Island. The Interagency Volcanic Event Notification Plan, Canada's volcanic emergency notification program, was established to outline the notification procedure of some of the main agencies that would be involved in response to a volcanic eruption in Canada, an eruption close to Canada's borders, or an eruption significant enough to have an effect on Canada and its people. It focuses primarily on aviation safety because jet aircraft can quickly enter areas of volcanic ash. The program notifies all impacted agencies that have to deal with volcanic events. Aircraft are rerouted away from hazardous ash and people on the ground are notified of potential ash fall.