45+ Aftershocks From Yesterday's 7.7 EQ in Canada, Multiple 5 and 6-pointers Continue to Hit The Area, Eerily Reminiscent of Honshu EQ

Here are some things I`ve watched in the past:

[link to en.wikipedia.org]
[link to www.thefullwiki.org]
[link to en.wikipedia.org]

FYI.

Here is Wiki`s view of this event:

[link to en.wikipedia.org]

The earthquake occurred as a result of oblique-thrust faulting near the plate boundary between the Pacific and North American plates where the Pacific plate moves approximately north-northwest with respect to the North America plate at a rate of approximately 50 mm/yr.

That would make this semi-true:

[link to www2.canada.com]

Ward said the area is known as the Queen Charlotte fault, where the earth's plates slide horizontally across each other in a strike-slip action, similar to what happens along California's San Andreas fault.

"Stresses build up because of that movement, and every so often we get the release of that stress in the form of an earthquake."

Ward said he wasn't surprised the tsunami warning was shortlived because the strike-slip movement along the fault doesn't generally trigger tsunamis.

"To trigger a tsunami you need to have a vertical movement of the sea floor, and it's that vertical movement that displaces water and triggers the tsunami," he said. "Because it's sliding across each other, you're not generally moving the water."

USGS sorts it out: it`s both oblique thrust and strike slip:

[link to earthquake.usgs.gov]

I'm not going to lower my guard, I cannot discount any theory based of earthquakes when all people in the field seem to agree that we really don't know anything about earthquakes.

Stay frosty.

Okay, now this is a true gem to find. I've posted some info in this thread showing previous strike slip in the Puget Sound as well as the area surrounding Mt Shasta and it can now be used to see what a HUGE event the 7.7 Charlotte Quake really was.

When you click on the link, let it load. You'll see the huge amount of tremors and slow motion slip that occurred all day yesterday.

On the left of the page towards the bottom, there is a PREV button, review the days before and then use the NEXT button to return to today.

Be patient, load times vary for plot data.

[link to www.pnsn.org]

Last Edited by Redpaw360 on 10/29/2012 03:11 PM

Thanks for that, Redpaw. From that site:

[link to www.pnsn.org]

"This earthquake likely applied some additional stress to the faults we are concerned with in the Puget Sound and will have local aftershocks that are prominent for weeks. As usual, the chance of further seismic activity in the immediate vicinity of this earthquake will be higher than normal for a while, but does not rise to the level at which any actions are warranted."

5.1 just now


[link to earthquake.usgs.gov]

Yukon just had +4 followed by a 2.5. The quake may send the stress north as evidenced by the swarm at the southern Alaska / Yukon zone.

Wasilla or Kaliforsky Alaska is the region I'll be watching for now.

Last Edited by Redpaw360 on 10/29/2012 05:22 PM

Did the Honshu quake fall on a full moon?

Southern Yukon Territory is waking up


3.0 just now previous to a 3.4, a 4.1, and a 2.5...

4.6 queen charlotte

Last Edited by littlemiracles on 10/29/2012 06:22 PM

No.

6.2 117 mi S of Masset


[link to earthquake.usgs.gov]




Last Edited by Too Dark Park on 10/29/2012 11:01 PM

Less than two hours to go for a Tohuku carbon copy to happen, based on past known events. In the last few hours based on my fellow GLP'ers righ above me posting the EQ info.... I'm still thinking that we could see something soon.

The Seismo's have not stopped, I've watched them all day pretty much. What is your opinions?

Is this over soon or are we looking at a larger long duration event.

Hey RedPaw,

I think any theory is valid when you're dealing with a M7+

I question the 'experts' that claim this has nothing to do with the CSZ. In fact, it pisses me off because I think this is the most important time for people to prep.

Let's look at the FACTS so far:

The Queen Charlotte & San Andreas are TRANSFORM faults CONNECTED DIRECTLY to each end of the Cascadia Subduction Zone.

Transform faults since they slide side to side normally don't displace water - So why was an urgent Tsunami warning issued? Was there vertical movement at the plate boundary as well they're not telling us about?

The number and intensity of earthquakes after the M7.7 are almost the same as Tohuku except there's been dozens more.

The last CSZ event was in 1700 - an M9.0 - This event was recorded by Japanese Tsunami record keepers and Coastal Indian tribes oral history - entire Indian villages on the coast were destroyed

Historical CSZ frequency is every 300-800 years

ETS was only discovered in 2000 - What they know about ETS is that it relieves some of the CSZ locked plate energy very deep, but it actually INCREASES the tension nearer the surface, causing a mega slip when it goes.

The big difference between Tohuku and Cascadia is the fact that the Juan de Fuca plate is locked between the Pacific and North America Plate - check out the graphic here [link to commons.bcit.ca]

I have not studied plate tectonics except for what I've taught myself on the web but I think the Juan de Fuca plate probably absorbs locked plate energy longer than just a standard 2-plate subduction zone. In my opinion, the downside to this is that when it finally goes, it goes bigger than anywhere else on Earth, possibly even higher than M9.0

As for destruction scenarios, I think that Vancouver Victoria Seattle Portland & Sacramento would see the most shaking from a CSZ event. You can expect fairly violent shaking for FOUR MINUTES!

The shaking will be stronger than what Tokyo experienced because the subduction is actually almost directly below the first four cities.

Our building codes are good though, and older structures have been seismically upgraded. Scary & lots of damage but survivable.

The biggest threat would be the Tsunami - I think it has the potential to be worse than Japan's, because if it comes down the Strait of Juan de Fuca and wraps around into the Georgia Strait & Puget Sound it will be MASSIVE - Also Alaska, The Columbia River, California Coastal Bays to SF, & Hawaii would be devastated.

Let's hope that the M7.7 was a 'normal' EQ and that we don't have to witness CSZ unhinging in our lifetimes.

That was a pretty well written out explanation that I've subscribed to since the Nisqually quake. I think your actually spot on for everything except duration of violent shaking, which I think will be 7-9 minutes....

I really respect that opinion/thought train you wrote, can I stalk you?

LOL - just kidding...

Stay safe

4.7 and 4.8....

Well the shaking continues on the Barry inlet Seismo, but there is a calm going on like Tohuku.....

Better to wait and be frosty, rather than just figure that it's over.

Oh, it's not over:

[link to www.earthquakescanada.nrcan.gc.ca]

"Oct. 30 UPDATE: Aftershocks continue...including a M 4.6 at 7:11 a.m. PDT today. Since the M 7.7 mainshock on Saturday night, close to 100 events of M>4 have occurred, including 2 of M>6. At the seismic station at Barry Inlet, small aftershocks are still being recorded every few minutes.

Oct. 29 7:49 p.m. A M 6.2 earthquake has occurred to the west of Haida Gwaii.

"Oct. 28 1:04 p.m. PDT UPDATE. A magnitude 7.7 earthquake has occurred offshore in the Haida Gwaii Region at 8:04 pm PDT on Saturday Oct. 27, and has been followed by numerous aftershocks. The strongest aftershock so far was a magnitude 6.3 at 11:54 am PDT on Sunday Oct 28. The aftershock sequence is expected to continue for weeks with the number and severity of earthquakes decreasing over time."

I don't know if you caught it, HaidaGwaiiRide, but I posted that the USGS has said the 7.7 was a strike-slip EQ combined with an oblique-thrust EQ. I assume this explains the difference in depths of the ongoing quakes. Most of the aftershocks are in the 10 km. range. The 7.7 was at 17.5 km, but some aftershocks have been deeper.

Canadian officials in charge of notifying municipalities about tsunamis are taking some heat for delays. Some had evacuated long before they got the call. I wonder if this is due to the combination of two types of quakes. Maybe they thought it wasn't going to displace water, but realized at some point that it would. For some reason, the USGS knew this had happened, so Americans were warned before the Canadians who live in the area.

The story is still being pushed in the media that this was only a strike-slip fault, when the USGS has already said that two different kinds of EQ occurred.

So if they can't get this information straight, do they really have a clue what's going on in the CSZ? I don't think so.

There were a 6.3 and a 4 in the last hour or so.
[link to www.iris.edu]

Magnitude 4.6 - QUEEN CHARLOTTE ISLANDS REGION

[link to earthquake.usgs.gov]

Thanks .02.

I'm on an EQ forums now, asking a few people about their thoughts on what we see.... A few just give canned answers, a few speculate all is normal.

No one really knows is the consensus based on recorded history, but there are patterns based on dates of past EQ's that show we are ramping up rather than slowing down in frequency of events.

Does anyone know the exact location of the Haida geoengineering experiment in Haida Gwaii? I read that the iron was dumped in international waters, but nothing more precise than that.

@Redpaw: What do you make of this?

[link to www.pnsn.org]

I'm not sure which seismograms to watch.

Weather event.

whoa! Is that representative of harmonic tremors ... ie, magma flow?

I'm not familiar with the geography ... is that anywhere near a volcano?

Hey AC 244,
Here is the link:
[link to www.earthquakescanada.nrcan.gc.ca]

Scroll down the list, find Barry Inlet or Naden to see what's happening on the island to the north. Barry Inlet is the closest to the action, with Naden being at the northern tip.

If you think you see an EQ, you can confirm with a quick switch to Naden.

Last Edited by Redpaw360 on 10/30/2012 02:07 PM

It's on the Olympic peninsula in Washington state, as is this one:

[link to www.pnsn.org]

The Olympic mountains aren't volcanic.

Thanks. I had found that link on the weekend, but it wasn't working for me. Overloaded, I guess.