Category: Earthquake Activity

British Columbia is headed back into another one of its riskier seismic seasons, raising the risk of "The Big One," earthquake experts say.  Every 14 months, the Cascadia subduction zone — which runs from northern Vancouver Island down to northern California — experiences what seismologists call a "slow slip."

The Science Behind the Quakes

The Cascadia Subduction Zone is a 1,000 kilometer fault that runs from Northern Vancouver Island to Northern California. The fault itself is a boundary between two tectonic plates: the Juan de Fuca tectonic plate is moving towards and getting forced under the North American plate that we live on. A section of that boundary has become locked together - the plates are no longer sliding smoothly. So, all that forward movement is being stored up inside the rocks, waiting for the day that the energy will be released as a catastrophic megathrust earthquake, colloquially known on the Pacific Northwest as the 'Big One'. The tremors caused by slow slips are different from routine earthquakes that occur in the Pacific Northwest, and they aren't felt on the surface because they originate so far underground.

Past Slow Slip Cycles Can Help Us Gauge Future Seismic Activity

During the slow slip, in late December 2015, around 8,000 mini-tremors were recorded. During this slow slip B.C.'s South Coast was hit by an earthquake that shook many people from their sleep just before midnight, in what one seismologist called the largest quake in the region in years. This 4.8M earthquake was recorded on December 29^th, 2015 at 11:39pm in Victoria B.C. Our regions seismologist Alison Bird describes the heightened risk, similar to the increased risk of driving in rush hour traffic.  "Going for a drive in the country on a Sunday, you're not that likely to be in a car accident. But if it's rush hour in Vancouver and there's a game on ... you're more likely to be in an accident. You're not necessarily going to be, but the probabilities are higher." "We are living in a seismically active area. We will have damaging earthquakes — they're guaranteed," Bird said. "A lot of people use that cycle to remind them to check on their kit, to review their plan, that sort of thing.” There couldn’t be a better time to go through your emergency plan and purchase supplies. Find a local GetMyKit.ca Emergency Kit retailer, or visit our shop.   We offer free Emergency Preparedness Workshops and are looking for venues across British Columbia.  Check our Facebook page for events near you, or contact our office 1-888-673-1222.   Sources: CBC News.ca Oct 10, 2016 - Johanna Wagstaffe CBC News.ca Feb 23, 2017 

“Active” might be an understatement as illustrated by 7.9 magnitude quake that rumbled through the Gulf of Alaska shortly after midnight.  This triggered several aftershocks and a wide spread tsunami warning for the US and Canadian West Coast which was thankfully cancelled this morning. While seismic activity and earthquakes are seemingly unpredictable, recent studies suggest that larger earthquakes and natural disasters are to come in 2018. Studies conducted by U.S. Geologists suggest that there is a strong correlation between the rotational speed of the earth and its seismic activity. Data recorded from the past 117 years shows significant slowing of the earths rotation coinciding with the fact that there have been 5 major earthquakes recorded in the past year opposed to an anticipated 20 per year to come in 2018. University of Colorado’s Roger Bilham has stated that 2017 was a rather easy year concerning earthquakes however 2018 could likely be the year that we start to see way more seismic activity based on research. Historically earthquakes range in magnitudes from 1 being minor consisting of trembling up to about 9.5 magnitudes destroying cities and killing hundreds and affecting thousands in its wake. They occur mainly and most prominently within the Pacific Ocean’s ‘Ring of Fire’, which consists of active volcanoes and mountains stretching 25,000 from New Zealand to the Eastern edge of Asia. 2018 Slow Slip – What is a “Slow Slip?” Movement between tectonic plates located deep beneath the earth’s crust are recorded as earthquakes.  Slow slips are similar to earthquakes because they are caused by movement between tectonic plates. They are different because they can take several weeks and up to months in worst case scenarios to have run their full course. By the time that this happens the slip has already had enough time to inflict traumatic experiences to those above the moving plates. Slow Slip events, like earthquakes, occur normally at ‘Subduction Zones’ which are tectonic plates that have recently coincided. Subduction zones currently exist near large bodies of water, several large zones recorded run through New Zealand, south Abbotsford and South Victoria. Tectonic plates move along each other laterally causing them to rub, emitting friction which then causes instability and shaking on the earth. Slow Slip fact: Slow slip earthquakes occur deep within the earth and can trigger earthquakes or possibly other slow slip events up to 600 miles in surrounding area from the epicenter. The last slow slip that occurred in B.C. and Northern Washington, more specifically from the lower mainland, Vancouver Island, was between December and January 2016 where more than 8,000 slow slip earthquakes were recorded along this fault line.  When earthquakes or slow slip events are recorded sequentially, they are recorded as ‘Preliminary Earthquakes’ meaning that they are most likely in anticipation of a larger more powerful earthquake. To Seismologist Alison Bird, the possibility of a larger earthquake is all too real. She will not park her vehicle in underground parkades due to the fact that the chances of an earthquake are so high. Alison Bird says “Every 14 months or so there’s a sudden reversal of movement in seismic activity… it could be a last straw scenario where just that little bit of extra stress that’s going to cause that rupture to trigger … the megathrust earthquake” Our next slow slip is this coming March, Science shows that British Columbia’s next slow slip will occur March 2018. Are you prepared?   Written By: Leigham Merlet