The likelihood of a forthcoming Cascadia earthquake and its impact on British Columbian infrastructure

(Inayat Dhaliwal, University of Calgary, Calgary, AB)

Throughout history, earthquakes have caused damage to numerous places. The repercussions continue to impact these earthquake-prone regions; therefore, it becomes necessary to assess future hazards. The great Cascadia earthquake of 1700 caused destruction to individuals and property across the Pacific Ocean, specifically in Japan (Satake et al. 1996). Other places, such as Alaska and coastal British Columbia may also be exposed to the effects; however, the damages that occurred in Canada from the last earthquake are not documented and remain unknown (Xie et al. 2012). The Cascadia earthquake is triggered when the Juan de Fuca tectonic plate, moves along the Cascadia subduction zone (Olsen et al. 2008). Most of the damage from this earthquake is caused by its effect on ground-shaking and tsunami height (Satake et al. 1996). This objective of this research was to analyze literature and discuss the likelihood of another great earthquake occurring in the Cascadia subduction zone and how it can extensively damage the infrastructure of Canadian metropolitan regions through ground shaking and tsunamis.

Earthquakes follow a cycle; therefore, a great Cascadia earthquake is most likely to reoccur (Mazzotti and Adams 2004). However, there is only a zero to twelve percent possibility that this earthquake will occur within 50 years. The possibility of this earthquake occurring is 30 to 100 times greater during slow-slip events. It was found that slow-slip events in Vancouver Island last 1-3 weeks and happen approximately every 13-15 months. As slow-slip events can be detected early and easily, they can provide great insight into the likelihood of a forthcoming earthquake so that precautionary steps can be taken.

This earthquake will cause ground motion of ten centimeters per second in Vancouver for two to five minutes (Olsen et al. 2008). Such ground motion can cause destruction to roads, railways, bridges, and buildings. It can also trigger landslides preventing access between regions (Hungr et al. 1999). This earthquake may instigate a tsunami, which would direct most of its power towards the Pacific Northwest, affecting BC (Xie et al. 2012). Wave heights of up to 25 meters would lead to coastal flooding, changes in land level, and damage to coastal infrastructure (Cheung et al. 2011). This catastrophe would result in billions of dollars of damage to Vancouver, a major Canadian city, and therefore, it is important to develop plan of action if such an event were to arise.  

This blog post has been written by Inaya Dhaliwal, fourth year undergraduate student at the University of Calgary working towards a double degree Bachelor of Science, Geology (Minor in Geophysics) & Bachelor of Science, Environmental Science (Statistics Concentration). http://www.ucalgary.ca/science/ 

Inayat applied for CatIQ's Canadian Catastrophe Conference's Student Delegate Program.