By: Eileen Chen
Despite living in a city built above a subduction zone, few Vancouverites invest effort and thought into preparing for “The Big One” – a magnitude 9.0 mega earthquake predicted to occur along the coast of BC. In face of uncertainty, we react readily in anxious denial and are afraid to ask further questions. “How do earthquakes occur?” “How accurately can they be predicted?” “How prepared is Vancouver in comparison to other world cities?”
Seismology – the study of earthquakes and seismic waves – can provide several answers to these largely unasked questions. Dr. Michael Bostock, a leading seismologist who teaches and conducts research at the University of British Columbia, sat down with the VACS team in the beginning of March to share his knowledge.
Dr. Bostock began his career by studying the formation and evolution of early continental landmasses, and now focuses on analyzing subduction zones in the Cascadia region, which spans from California to North Vancouver Island. His work involves studying seismograms recorded by seismograph stations across the SW British Columbia, and analyzing the structure and seismicity in and above the Juan de Fuca Plate as it slowly slides beneath our continent. “We face hazard from more than ‘The Big One,’” he declared.
The nature of the near surface has a great role to play in the amplification of waves from earthquakes, and areas such as Richmond are particularly at risk due to water-laden sediments, whereas the Arbutus area is comparatively safe as it is founded on a more solid bedrock. Still, Dr. Bostock reminds us that no part of Vancouver is earthquake-proof: “There are lots of risks one takes – living here is a risk.”
It would not take a 9.0 earthquake for irreparable damage to be done. Dr. Bostock believes that the city does not make available enough information on seismic upgrades to housing. In comparison to Seattle and Portland, which have programs to encourage and subsidize the seismic upgrade of homes, “Vancouver is behind in some respects.” At the very least, citizens need to be better informed.
Dr. Bostock discussed the importance of having wood frames bolted to concrete foundations, which prevents structures from dislodging from their bases in case of a serious earthquake. Many houses built before the 1990s lack this insurance. He himself upgraded his house this way, and called the upgrade “a simple change that can modernize older homes.” The material and design of houses also matter. Whereas wood is more elastic, concrete will crack and break under violent tremors unless it is well reinforced. In addition, the sparse internal walls in spacious houses that modern architects favour for aesthetic purposes can create additional weaknesses.
Of course, one cannot skirt around “The Big One” in a discussion of earthquake preparedness in Vancouver. Dr. Bostock, alongside most experts, predict that the chance of the magnitude 9.0 earthquake occurring within the next 50 years is approximately 20%. This prediction is based on “statistics and probability,” as we currently lack the technology to predict seismic activity based on immediate observations. Still, Dr. Bostock explains that “standard deviation and mean is already enough to tell us quite a bit.” Paleoseismology – geological records of historical earthquakes – provides us with detailed information on the ~20 megathrust earthquakes that have occurred in the Cascadian region in the last 10,000 years. This amounts to one around every 500 years, the last for which we know the date quite accurately (January 26, 1700).
In addition to studying seismic records, we can learn about earthquake resilience from other cultures. Dr. Bostock observes that as the most earthquake-prone country on the planet, Japan probably has the best-informed public and some of the top researchers in the world. Indeed, Japan has a rich folklore surrounding earthquakes. As an example, Dr. Bostock produced a folder with a printed ukiyo-e of a catfish (namazu) from his bag, given to him by a colleague. He remarked that through art, earthquakes have become an “element of [Japanese] culture.”
Even 300 years ago in BC, several First Nations accounts of the 1700 earthquake transformed the event into colourful tales of justice, revenge, and terrible mistakes, which the student-geared group workshops at UBC’s Museum of Earth highlight. The Quileute and Hoh people describe a fight between Thunderbird and Whale, and the Nuu-chah-nulth people on Vancouver Island tell a different story involving a dancing man with “earthquake-foot” (Finkbeiner, Hakai Magazine). Such a creative view towards earthquakes is a sign of a resiliency that our urban culture currently lacks.
When asked if earthquakes bring any positive impacts to the environment, Dr. Bostock pointed out that our mountain ranges are a manifestation of slow but steady growth that occurs partly through earthquakes. In addition, not all earthquakes are dangerous. Those beneath a magnitude of 2 happen regularly throughout the year but are imperceptible to humans, and those beneath a magnitude of 4 cause little harm. Dr. Bostock suggested that one can learn more about earthquakes by watching slow earthquakes – subdued magnitude 6.0 – 7.0 earthquakes that take place imperceptibly over weeks (rather than seconds to minutes for regular earthquakes) – with the help of technology on Vancouver Island.
In an age of global climate change concerns, we as first world humans tend to assume the burden as culprits behind all natural disasters. In terms of causing earthquakes, Dr. Bostock clarified that climate change and human causes such as fracking have relatively little impact. The quakes caused by fracking generally lack the power to cause widespread damage; it is the implication that further release of CO2 through the continued burning of hydrocarbons that is more harmful to the environment. Dr. Bostock added, “Fracking is a social issue that we have to deal with. We need to alleviate our dependence – our addiction – to fossil fuels, and trust scientific prediction for our kids’ safety.”
The only type of human activity that causes larger (magnitudes 5 and greater) earthquakes is nuclear testing which was more commonplace in the 1950’s-1980’s and typically conducted in deserted areas. Dr. Bostock revealed that it is no coincidence that test sites are often established on earthquake zones, in an attempt to mask nuclear test operations. Still, modern seismology is able to distinguish between genuine earthquakes and nuclear bombs, as collisions and explosions result in different seismic radiation patterns.
On the topic of the future of seismology, Dr. Bostock notes that many seismology students used to work in the oil industry to explore for hydrocarbons rather than in earthquake research. More recently, seismologists are increasingly employed in the capacity of environmental stewardship to monitor seismic activity in fracking operations and in the sequestration of waste products underground. While he himself considers his research “a bit of a hobby” that he got drawn to naturally through curiosity, he emphasized that earthquake research “is important to society, and doesn’t have dubious connections with hydrocarbons.”
Canada still has much room for improvement, but seismologists are currently investing great effort into accessing ocean depths through cabled observatories and establishing an earthquake early warning system. As long as we continue inviting people to engage in relevant conversations and learn about equipping themselves against hazards, we are on a positive track to building resiliency.
For more information on how to prepare for earthquakes in your local community, check out our previous article on Kerrisdale Earthquake & Emergency Preparedness (KEEP), or attend a KEEP workshop in April or May: