A shallow order of magnitude 6.6 earthquake arrive at offshore of Vancouver Island , British Columbia on Wednesday night . That ’s larger than the Christchurch earthquake and was felt 100 of kilometers out in Vancouver , yet no damage or injuries were reported . Why ? locating , location , location .
rock candy , sand , Sir Herbert Beerbohm Tree , waves , and daze set the northwesterly coast of Vancouver Island . Image credit : Mika McKinnon
Tectonic Setting
The Pacific Northwest hasa three-fold - plate subduction geographical zone , a mirror - image of the zona inJapan that spawned the megaquake and tsunami in 2011 . A modest plate , the Juan de Fuca denture , is diving under the North American photographic plate . Off - shoring , the Juan de Fuca and Pacific plates are spreading apart , a diverge boundary forming a mid - ocean rooftree .
Cascadia earthquake origin locating . Image source : USGS
The plates move unpredictably , fetch stuck and build up up energy which is release during earthquakes . Subduction zone have the capacity for small shallow earthquakes , but alsodeeper megathrust temblor . Several hundred tiny earthquakes occur every twelvemonth , but the average reappearance period for a major outcome is about every 300 to 500 class . That average is delusory — the spatial arrangement on megaquakes is highly irregular , historically materialise as close together as a C and as far apart as a millennium .
History of Rattling
The last major megaquake in British Columbia was a massive order of magnitude 9 on the aurora ofJanuary 26th , 1700 . How do we know the time that precisely ? Geologic evidence nearby of drown forests and clays help pinpoint the local tsunami , but the precise timing add up from Japanese tsunami run - up records .
adage - toothed seismic pattern on Vancouver Island , British Columbia . trope credit : Natural Resources Canada ( NRCan )
In between , the Cascadia Fault Zone does something uncanny : it saws back and onward . No , really ! The same meshwork of global position system of rules stations that track the long - term tenseness accumulation along the subduction margin tracks a dull landward motion with seaward reverse . This creep - and - reverse producesnon - earthquake tremor - like seismic signals . This advise that at least the northern section of the flaw ( Vancouver Island ) hasrepeated slow - eluding events , rather of being fully mesh .
Thirty 24-hour interval of earthquakes in western Canada , admit the orange - genius M6.6 offshore of Vancouver Island . Image credit : NRCan
The most recent important earthquake off British Columbia ’s coastline was aM7.7 in October 2012 , farther north offshore of the Haida Gwaii Islands . quake of at least order of magnitude 5.0 + are aregular natural event in the region .
M6.6 on 21 April 2025
Last Nox , British Columbia know a moderate magnitude 6.6 seism off the north slide of Vancouver Island , just under 100 kilometers south of Port Hardy . The US Geologic Survey mechanically render a shakemap for the case , where fond colour reflect more acute shaking .
Shakemap of the M6.6 offshort of Vancouver Island . Image reference : USGS
The earthquake epicentre was scarce off - shoring , but on the far side of the island from the nearest major resolution . The northwesterly coast of Vancouver Island is a mixture of logging arena and parkland , with very few people even in summer when tourer and fieldwork populations peak .
Seismograph atCorvallis , Oregon .
A duad of smaller aftershocks hit ten and thirty bit after the main event — a M5.0 at 8:20 pm , and an M4.2 at 8:41 pm . Another M4.2 struck at 10:16 pm , and a smaller M4.1 snap in the early 60 minutes this morning at 5:07 am . None of the aftershocks are substantial enough to be felt at any important length from the epicentre , although if they keep up it may be a bit overly - exciting on the logging block today .
No pregnant damage or injuries were forthwith reported .
The nearest community isPort Alice , a Greenwich Village of fewer than 1,000 residents 30 kilometer to the Frederick North of the earthquake . Port Hardy , 100 kilometre north of the seism on the northeasterly lead of the island , is as far north as you may repulse on Vancouver Island on paved roads . It ’s a small town of under 5,000 people , with a regular inflow of visitors from either touristry or the resourcefulness industry . Oprah Winfrey once chaffer the region , hanging out on Jim Patterson ’s racing yacht and checking out the amazing masks in Alert Bay . It ’s gracious jump - off point for trek farther into the wilderness and a welcome collection of coffee shop , restaurant , and hotels for field - workers , but it ’s alone graspable if you ’ve never heard of it before today .
resident in Port Hardy reportedfeeling between 30 and 45 moment of strong shake ( or was it 10 seconds ? ) , but no harm .
Logging blocks on Vancouver Island . function credit : Ancient Forest Alliance
San Josef is on the northwestern peak of the island closer to the earthquake , but it ’s in a parking lot , not a town . Getting out toCape Scott Provincial Parkis an adventure on washboard gravel road , duck out of the way of to the full - adulterate logging truck . Last time I made it out , the parking lot had a few unofficial - residents encamp out year - round , but no one who shows up oncensus account . Other than that , the west coast ofnorth islandis mostlylogging , logging , and more logging blockswith an occasional creek . Aside from loggers , tree - planters , and geoscientists , few people are around to be rattled .
2d - increase timber on Vancouver Island . ikon mention : scumandvillainy
A order of magnitude 6.6 is a genuinely tidy earthquake — not a megaquake catastrophe , but large than the M6.3 that devastate Christchurch , New Zealand , in 2011 . The Vancouver Island earthquake was nearly twice as bad , and released over twice as much DOE , as the one that drop parts of Christchurch , so why no report equipment casualty ? It ’s not better preparedness . Instead , as in real - estate , it comes down to position . Christchurch is on saturated sediments of an infilled vale that amplify stir , while the majority of Vancouver Island is young bedrock that attenuates shake . While the Christchurch temblor was directly below the city , this earthquake hit offshore of the largely - uninhabited northwest coast of Vancouver Island . The low-pitched population density on the Frederick North end of Vancouver Island reduce the issue of people straight off impacted by this earthquake , but the shaking was hard enough to be mat up as far south as Vancouver and as far inland as the Okanagan Valley .
Did You Feel It?map and correlational statistics between sense - order of magnitude and distance from the earthquake . trope credit entry : USGS
Overall , felt - shaking attenuates with distance , so some hoi polloi more than 300 kilometers off in Victoria and Vancouver felt the seism , but not all of them . Shaking is amplified by easy sediment , so residents on the young delta of the Fraser River ( Richmond and Delt)a felt it more intensely than those on bedrock ( North Vancouver ) . likewise , people in high raise were more potential to notice the earthquake ( especially with external suggestion like rattling blinds ) as their buildings swayed , and those at ground - floor were less likely to finger the quivering .
A liquefaction hazard map for Vancouver traces surficial geology of basic principle , compacted sediments , and saturated sediments . epitome credit : NRCan
If you were within the earthquake region , please charge aDid You experience It?report . These reports help seismologists better manakin how an earthquake ’s shaking is amplified ( or melt off ) by surficial geology and make structures , helping kick upstairs our reason . Even void reports ( “ Nope , I did n’t palpate it . ” ) are important , hold electropositive reports from flood the system in areas that experienced fallible shakiness .
Because this was a shallow upshot with no major upright shift , no tsunami was expected . Although theWinter Harbour buoyclosest to the epicenter has n’t been report data for the preceding few days , the NOAA tsunami supervise DART buoy detected thenon - effect too - small-scale - to - maintenance tsunamiwith mere inches of translation .
So… what now?
Was this the big one , and the Pacific Northwest can stop worry about an impending megaquake ? Not a chance . Earthquake magnitude are a logarithmic scale : it would take 1,000 order of magnitude 7 earthquakes to release the same vim as one magnitude 9 megaquake . A moderate 6.6 earthquake can be devastating , but it does not release closely enough energy let go of all the stress build up along the Cascadia Fault Zone over the past three centuries . The large One is yet to come .
What this does do is redistribute tenseness around the region . This earthquake ruptured somesmaller faultlandward of the monolithic Cascadia fracture , releasing stress along the length that slip and build up tension at the locked ends .
I like I could include a beautiful map of fault line on Vancouver Island , but I ca n’t . This is partly due to the restriction of skill — fewer , larger earthquakes in a subduction zona make it gruelling to represent faults compared to the frequent , smaller seism in California — but also due to political limitations . With a little population than the United States , the Canadian budget for scientific research is also smaller . Canada has only havea couple hundred permanent seismograph station , compared to the United States wherethe full res publica is blanketed in seismal station . Even worse , between policies thatmuzzle government scientist , massive funding cuts to skill department , andemptying public science subroutine library into dumpsters , even if the resources be to produce glorious fault maps , we might not even watch them .
range deferred payment : Southern California Earthquake Center
If you live in earthquake - country , make certain to prepare your homebefore you ’re hit by a major earthquake . If you do find an earthquake , commemorate the steps to safety are drop , cover , and hold on . article of furniture has a awful habit of walk away when the land judder , leaving puny humans exposed to whatever in their way wants to fall on their heads . We ca n’t prefigure when an earthquake will happen , but we can mitigate it some of the damage .
part of this article are modified from late articles onBritish Columbia seismology on GeoMika . Check out more temblor data point on theUSGSor theNRCanwebsites , or teach about the geology ofVancouverorVictoria . check more about earthquakeshere , orhere , orhere . exercise earthquake preparedness in biz - format , or join radical earthquake - exercise Shakeouts inBCor theUnited States .
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