Hear what an expert has to say about these fascinating events
Photo via Earthquakes@UVic.
Ed Nissen is a professor and Canada Research Chair at the School of Earth and Ocean Sciences at UVic, who specializes in seismology: the study of earthquakes. In an interview with the Martlet, he answered all of our questions about earthquakes, including whether or not they’re connected to climate change.
According to Nissen, an earthquake is “a sudden release of stored elastic strain energy within the Earth caused by the motion of tectonic plates.” But what does that mean? We had him explain further.
The Earth’s outer shell is made of rigid plates. These plates can move into, under, past or apart from each other, explained Nissen. The stress of these movements causes strain to build up along faults — the lines deep underground where the Earth’s plates meet each other. Most of the time, these faults are locked in place by friction. Sometimes, when the stress becomes too much, the faults slip. This slip is an earthquake.
You might have heard people talking about “The Big One,” a massive earthquake that is set to hit the West Coast of North America. We asked Dr. Nissen to explain this idea, and how likely it is to happen.
“The main fault that we think about in British Columbia is actually offshore,” said Nissen. “It’s called the Cascadia Megathrust.” At this fault, also called the Cascadia Subduction Zone, the Pacific seafloor is being pushed underneath the North American plate, he explained. “Most of the time the fault is locked, and then every few hundred years, it ruptures in this giant earthquake.”
Proper language is important in communicating when an earthquake, like “The Big One,” might happen, said Nissen. He explained that, in seismology, prediction is impossible. A prediction would mean that the seismologist knows exactly where an earthquake will happen, at which magnitude, and at what time.
Instead, researchers like Nissen focus their time on forecasting the likelihood of an earthquake happening in a given region, rather than predicting individual events. This is called probabilistic seismic hazard analysis, but can also be referred to as forecasting, he explained.
According to the latest forecasting, there is a one in three chance of a major earthquake caused at the Cascadia Subduction Zone happening in the next 50 years. “The Big One is inevitable,” explained Nissen. “It’s not a matter of if, it’s a matter of when.”
And when it does happen, the impact on Victoria will be enormous. Nissen says the risk is high enough that measures should be taken to reduce casualties. “We should do things like prepare, retrofit schools, retrofit hospitals, [and] make sure building codes are strong.”
While the technology has not yet been implemented in B.C., there is a system to warn us about this earthquake moments before the shaking starts. It’s called earthquake early warning. “[It’s] not predicting, or even forecasting,” said Nissen. “It’s a very rapid detection of an earthquake that has just happened.” He explained that sensors would be placed underwater, at the Cascadia Subduction Zone, that will alert people on land if they detect movement of the plates.
Nissen said that this system, which is already in place in California, Oregon, and Washington, will be implemented in B.C. in the next three to five years. This means that we would have an app on our phone to let us know that an earthquake is about to start, he said.
Climate change has an impact on nearly all of our lives, and we were curious about how it might affect earthquakes. Dr. Nissen explained that, in most of the world, climate change cannot cause these events. “Earthquakes are driven by stresses at the scale of the Earth’s crust — so we’re talking depths of 10, 20 km,” he said. “The stresses from weather or climate are negligible.”
One exception is in Antarctica, where rapid loss of ice caused by warming temperatures can trigger the movement of the mantle, the layer below the Earth’s crust. This can cause earthquakes, but it isn’t a major cause for concern, said Nissen.
He’s more worried about what might happen if a climate change-related weather event took place while an earthquake did. “If an earthquake happened during an atmospheric weather event, I think that would be such a nightmare,” Nissen explained. He said that, when the ground is wet, earthquakes can easily trigger landslides and lead to more catastrophic damage.
Nissen is also concerned about what might happen if an earthquake occurred during a heat dome, like the record-breaking one we saw in 2021. “There would be lots of people probably sleeping outside in very hot temperatures,” he said. Nissen explained that debris would get in the way of first responders, who would be already busy during the emergency, and struggling to manage fires from broken gas lines.
“I think climate change is what I worry about much more than earthquakes,” Nissen said. “It’s putting life on Earth at risk.” Though he doesn’t often think about the interplay between climate change and seismology, Nissen said that the two are certainly linked when it comes to the risk of human life. “As climate hazards and bad climate events happen more and more regularly, the chances of a big earthquake happening during one of those events is going to go up.”
Dr. Nissen is an advocate for earthquake preparedness, and even includes an assignment where students have to build an earthquake survival kit in his Natural Hazards course, EOS 170. It’s an elective open to all UVic students where they learn about earthquakes, climate disasters, and more.
Anyone interested in earthquakes can check out UVic’s Earthquakes Group website to learn more about Dr. Nissen and his research team.
