An earth sciences professor says an earthquake off the west coast of Vancouver Island today is a reminder to ensure we are prepared in the event of a tsunami.
The 6.2 magnitude earthquake hit over 200 kilometres off the coast and there was no tsunami warning. However, Brent Ward of Simon Fraser University says quake size is not what necessarily what determines if a tsunami will happen.
“Usually, it has to be over a 7 at least to really trigger a tsunami but what’s more important here is the nature of the earthquake in terms of the relative movement of the rocks,” said Ward.
“This earthquake was largely what we would call a strike-slip where the rocks were moving side to side. To really generate a big tsunami, we need to have vertical movement of the seafloor and it’s that vertical movement that displaces the water that then triggers the tsunami wave.”
Ward says they figure this out through understanding the fault type and by looking at the nature of the waves released from the quake.
He adds the distance is also less important and tsunami waves can travel across the ocean and hit multiple areas of coastline. While the earthquake did not pose any risk, these earthquakes are always a reminder that we are in a subduction hazard zone.
“It’s a good time for people to think about what they would do during an earthquake,” said Ward. “If you feel the ground shaking intensely, as soon as that shaking is over you need to move to higher ground because you’re only going to have 20 or 30 minutes before the tsunami hits the shore.”
Ward adds it is not usually just one wave, and the subsequent waves can be even bigger and more damaging. He says it is important to have an earthquake kit ready and have a plan with your family on how to meet up after and communicate.
More earthquake areas are being discovered that happen in the North American crust, with active faults found in the Victoria area that would cause intense ground shaking.
Ward says that while it should not cause any worry, the area is starting to get into the time frame of when a larger earthquake could happen and now is a good time to be prepared if it happens.