Vancouver is located in a highly active earthquake region, better known as the Cascadia Subduction Zone. This area spans from the north of Vancouver Island to northern California. This is an extremely delicate zone which is known for being highly unstable due to the interaction between the two tectonic plates present. The Juan de Fuca plate is located just off of the shore of Vancouver Island and adjacent to it is the significantly larger North American plate. Throughout time, the Juan de Fuca plate has been slowly creeping under the North American plate – this process is called subduction. The nature of the tectonic plates has placed Vancouver in a precarious situation. The constant pressure, grinding and subduction between the plates has caused an immense amount of pressure which has been released through earthquakes. Although this pressure is released daily in the form of small-scale earthquakes, which go virtually unnoticed, researchers have reason to believe that a large scale earthquake will occur in the near future, and this event will be devastating, likely disrupting the city as a whole.
In order to prepare for events like these, Vancouver has designated safety/disaster hubs located all across the city, there are 27 to be exact. In the event of a disaster, these sites will be used as refuges where individuals can collect themselves following a natural disaster and devise a plan to help them act in a swift and efficient manner in the hours after a natural disaster such as an earthquake. The aim of this project is to analyze how efficient the distribution and location of the 27 disaster support hubs are with respect to the population in the City of Vancouver. This project intends to show what safety hubs provide the support necessary for each neighbourhood. In our analysis we considered multiple variables, including surficial geology, Vancouver’s road network, safety hub location, hospital location and schools due to their resilient architectural structure and ability to withstand large scale magnitude earthquakes.
Given that the fact that the city of Vancouver has already created disaster and earthquake response plans, we evaluated and contrasted our results with those currently available in order to suggest modifications and improvements with the hopes of creating a more resilient and prepared community in the event of a large-scale earthquake. Moreover, we managed to create various maps which delineate and provide the most efficient route to safety. Through the careful examination of the spatial distribution of safety hubs located throughout Vancouver we realized that some of them exist in areas of grave danger and must be relocated in order to ensure the safety of the community.
Since Vancouver is located in a highly active earthquake zone it is important to prepare for the inevitable: a large scale earthquake that could severely impact the city and the life of its citizens. In order to comprehend why Vancouver is at such a high risk of devastation, we must understand its geographical location and the risks associated with it.
Terminology:
- Surficial Geology = Refers to the nature, distribution, age, and origin of deposits. This is relevant because different soils behave in uniquely when undergoing an earthquake and some are more prone to failing than others.
- Liquefaction = Occurs when vibrations or water pressure within a mass of soil cause the soil particles to lose contact with one another, resulting in soil that behaves as a liquid.
- Safety hubs = Sites of gathering, assistance, coordination of aid, governmental services, and shelter after a major disaster, in this case, an earthquake. Some safety hubs were found to be located in prone-to-failure zones, we suggest other sites as safer safety hubs.
- Cascadia Subduction Zone: Also known as the Cascadia Fault. This convergent plate boundary stretches from north of Vancouver Island to northern California. This area is where the North American plate and the smaller Juan de Fuca plate meet, creating a subduction zone where the heavier oceanic Juan de Fuca plate is sliding under the continental North American plate thus creating a scenario for a megathrust earthquake.
As seen in Figure 1, Vancouver is geographically located on the Cascadia Subduction Zone, a fault that has the potential of creating magnitude 9.0 earthquakes on the Richter scale (Disaster and Earthquake Response, 2016). Research shows that there is a one in four chance that we will have another major earthquake within the next 50 years (City of Vancouver, 2017). Furthermore, land tremors of such severity have not occurred in more than 300 years making the possibility of such an event occurring a matter of time very likely.
According to The City of Vancouver’s “Earthquake Preparedness Strategy Update” (2011), many buildings in the city were constructed with little to no consideration of earthquakes. Indeed, due to the fact that 60% of the buildings in the city do not meet the 1973 upgrade to the building seismic code, city planners are expecting many neighbourhoods to be affected within the urban area. Figure 2 shows the locations of buildings pre-existing the 1973 upgrade to the building seismic code. Areas of particular vulnerability include the Downtown West End, the east side, sections along Kingsway and Broadway, and the City’s South along the Fraser River (Earthquake Preparedness Strategy Update, 2016).
These pressing facts have urged the city of Vancouver to create an emergency response plan that evaluates the preparedness and distribution of safety hubs across the city. Furthermore, the creation of a comprehensive action plan that takes into consideration the delineation of evacuation routes and the correct preparation of safety hubs in response to an earthquake is necessary.