Juan de Fuca Plate Activity

[dgavin]

One of the unnamed Sea Mountains on the Juan De Fuca plate experinced a whooping 5.1 earthquake about an hour ago ~ 10:48 am PDT.

Location: http://maps.google.com/maps?f=q&source=s_q&hl=en&geocode=&q=44.407N+129.339W&sll=44.407,129.339&sspn=0.169723,0.227623&g=44.407+129.339&ie=UTF8&ll=44.613934,-129.193726&spn=2.705947,3.938599&t=h&z=8

Although this is close to the Blanco fracture zone, it's an unkown at this point if it is Tectonic or Volcanic.

[Gillianren]

Ah. No wonder I didn't feel it--for the curious, it's out west of Coos Bay, Oregon, a couple hundred miles offshore.

[korjik]

well, the Mayan calendar ends in 2 and a half years...

:D

[dgavin]

No Tsunami warnings have been issued, although informational statement was released by NOAA.

A Magnitude 3.1 and 3.9 earth quake just /now/ occured in the same region.

[dgavin]

The 3.1 was Upgraded to 3.8 Mag.

There was another 3.9 and 4.3 earth quake in same region. These are too strong to be normal aftershocks. Still unknown if Volcanic or Techtonic. Depth of events have decreased from 28km to 10km.

[dgavin]

Another Quake Mag 4.4 in same region, back to 28km+ depth.

[dgavin]

Latest Log, with updates to depths and Magnitudes.

MAG UTC DATE-TIME y/m/d h:m:s LAT deg LON deg DEPTH km Region
MAP 4.4 2010/05/07 20:02:19 44.496 -129.418 10.0 OFF THE COAST OF OREGON
MAP 3.9 2010/05/07 19:15:59 44.527 -130.659 10.0 OFF THE COAST OF OREGON
MAP 4.3 2010/05/07 19:03:31 44.536 -129.557 10.0 OFF THE COAST OF OREGON
MAP 4.4 2010/05/07 18:55:04 44.508 -130.052 10.0 OFF THE COAST OF OREGON
MAP 4.2 2010/05/07 18:51:00 44.490 -129.557 10.0 OFF THE COAST OF OREGON
MAP 3.9 2010/05/07 18:48:37 44.458 -129.107 10.0 OFF THE COAST OF OREGON
MAP 4.5 2010/05/07 18:43:08 44.456 -129.410 10.0 OFF THE COAST OF OREGON
MAP 4.4 2010/05/07 18:41:55 44.407 -129.456 10.0 OFF THE COAST OF OREGON
MAP 5.1 2010/05/07 17:46:15 44.396 -129.437 10.0 OFF THE COAST OF OREGON

[Swift]

You know, my wife and I are planning a trip to the Pacific Northwest this fall. Between this and Mount Hood, I might have to change our plans to the beautiful beaches of the Gulf Coast. ;)

[Gillianren]

They are awfully beautiful beaches. If you choose to visit scenic Olympia . . . well, we don't really have much in the way of beaches. But you can come by for dinner!

[jj_0001]

There are some really beautiful beaches out on the Olympic Peninsula and Oregon Coast.

Hmm, where is my shot of Ruby Beach?

http://i238.photobucket.com/albums/ff228/jj_0001/rubybeach.jpg There ye go.

As to Hood? Well, you could drive down to Ca. if you needed to get an ash-free airport, and anyhow, volcanos do this all the time, and usually don't go off.

The south edge of the Juan de Fuca plate? It seems to shake every month or so.

[geonuc]

The USGS doesn't have a 'beachball' for this quake (why?), but it is right next to the transform fault which has exhibited only transform-related strike/slip movement in the recent past.

http://neic.usgs.gov/neis/bulletin/neic_vzbx_m.html

[dgavin]

Seam to be fault related, and nothing new today from it. Still all but one of the events was dirrectly under a Sea Mount. All told it looks like it relesed as much energy as a single 6.0 quake.

[Jens]

One of the unnamed Sea Mountains on the Juan De Fuca plate experinced a whooping 5.1 earthquake about an hour ago ~ 10:48 am PDT.


Whooping? You mean like the cough? Or do you mean "whopping"? If so, is 5.1 really so big?

BTW, we had an interesting earthquake during lunch yesterday. It was just 4.0, but it was really right below us. There was no shaking, but we felt these kinds of thuds coming up from the ground. The epicenter was like 40 km under us.

[Gillianren]

5.1 is not that big. However, a whooping earthquake would be interesting to experience. Much more unusual than the ordinary rumbling ones.

[dgavin]

Yes well, while whooping quakes might be a bit more entertaining the whopping ones, I had ment the latter:P

Looks like this seiries is over, still nothing since the last 4.4 on Thursday. Neither USGS or NOAA has made any sort of statements yet.

So as it sits it's looking like this is transform fault activity, as mentioned by geonuc, even though most of these occured under a Sea Mount its very unlikely this is releated to volcanism of a it.

[dgavin]

There was another 5.1 Mag Quake on the Jaun de Fuca Plate off Oregon coast, this time located in the North Gordo (http://earthquake.usgs.gov/earthquakes/recenteqsus/Maps/US10/37.47.-130.-120.php) region.

Again no tsunami warnings will be issued for this event.

[dgavin]

Just a followup on the new 5.1 Quake from yesterday , it was followed by a 4.1 quake in the same region and then by a 2.7 in the South Gordo area.

[dgavin]

A busy quake day for the oregon, another 4.1 and then 4.0 in the North Gordo region of the Jaun de Fuca plate.

Quite a few meduim sized quakes in the last month on this plate. Haven't heard of a historical president for these size of quake's in the quantity there happening, so don;t know what to make of it, other then as Vulancs might say, "Fasinating."

[dgavin]

Nothing new to report here.

However I did go through the historic quakes data a bit over the weekend, and actualy quake swarms of these sizes are entirely normal for the region. The plate seems to produce very few quakes under a 3.0 magnitude historically.

This might be due to the lack of a siemographs near the active regions of the plate, but I don't think that is the case these days. The Mt Hood 2.7 quake was picked up easily on Crater Lake and Mt. Shasta siesmographs, which is further in distance then the events were to the on shore siesmology stations.

[dgavin]

One more smaller quake last night 3.4 mag at the south transform fault between Jan de Fuca Plate and the Pacific Plate.

Over all an intresting series of events, starting with a single quake on the north of the plate roughly east of seattle, followeed by swarms of mid range earth quakes that slowly seem to migrate south. Can't say I've ever heard of Jaun de Fuca quite being this active EQ wise before, It's allready hit it's yearly average of quakes in just a matter of three weeks. I do not think it portends anything at this point.

[dgavin]

Another 3.0 along the transform fault between Jan de Fuca Plate and the Pacific Plate today. A bit closer to the coast then the last one.

[geonuc]

I wonder if all the stress being relieved at the transform fault will be transferred to the subduction zone? In other words, as one section of the micro-plate boundary loosens up, the leading edge gets more stressed.

[dgavin]

Geonuc

As the North to south migration of the swarms alonth the transform regions do indicate some sort of release of stresses there, I think it's safe to say the pressure might be trasfered towards the direction of the subduction region. Not much is really known about the Jaun de Fuca Subduction zone and plate historically though, other then the Native's legends of the 'Thunderbird' which might of been a description for a megatrust event.

It's only been recently monitoed (past 30 years or so) by siesmographs so there are a lot of unknowns about this tiny, state sized tectonic plate. But what you are wondering, makes sense to some degree from what this swarm event is doing.

[dgavin]

A minor 2.8 Quake today at the junction of the Jan De Fuca, North American, and Pacific Plates. Again eastward location from pervious. I think you have the right of it geonuc, its starting to look like a gradual migration of plate stresses.

[dgavin]

Three more quakes at the south junction of Jan De Fuca and Pacific plates today, largest being 4.2 mag.

[dgavin]

There were a few more minor quake following my last post, not very notable.

However today there was another 4.4 Magnitude quake located back in the same region of the originally posted about 5.1 Quake.

[dgavin]

Well Jan-de-Fuca isn't quite done yet. There was a 5.1 EQ a few weeks ago on the canadian portion of the plate, followed by a 4.7 in the same region yesterday.

[dgavin]

About 3 hours ago there was a 5.3 quake just 85 miles WNW of Coos Bay Oregon, just 15 miles W of the Juan de Fuca/Contiental Plate interface. No Tsunami warning issued for this quake.

Location on Google Maps (http://maps.google.com/maps?q=43.7704+-125.8025(M5.3+-+OFF+THE+COAST+OF+OREGON+-+2010+July+28++16%3A12%3A06+UTC)&ll=43.7704,-125.8025&spn=2,2&f=d&t=h&hl=e)

Although I don't really like saying this, these medium sized quakes over the last few months are now about double of the yearly average. I think there is a small, very small chance at this time these might be precursor events to a megathrust quake event.

[jlhredshift]

About 3 hours ago there was a 5.3 quake just 85 miles WNW of Coos Bay Oregon, just 15 miles W of the Juan de Fuca/Contiental Plate interface. No Tsunami warning issued for this quake.

Location on Google Maps (http://maps.google.com/maps?q=43.7704+-125.8025(M5.3+-+OFF+THE+COAST+OF+OREGON+-+2010+July+28++16%3A12%3A06+UTC)&ll=43.7704,-125.8025&spn=2,2&f=d&t=h&hl=e)

Although I don't really like saying this, these medium sized quakes over the last few months are now about double of the yearly average. I think there is a small, very small chance at this time these might be precursor events to a megathrust quake event.

Is it possible that the built up strain is being released in small chunks? (yeah, I know, we'll know, after.)

[dgavin]

Is it possible that the built up strain is being released in small chunks? (yeah, I know, we'll know, after.)

Basicaly thats the rub. It could just be small releases of pressure which is the most likely case, or it could be precursor events to a megatrust, the unlikely case.

However we won't really know till after like you said.

The frequency of quakes in the short time frame is unusual. Thats about the only thing that can be said point positive about it.

[dgavin]

I've been researching things to find any alternative explaination about why suddenly there are so many medium sized events here in the last few months, as opposed to what i said three posts ago.

It seems that in January/Febura, NOAA released a series of under water siesmographs onto Jaun De Fuca plate. While that might account for an increase in reporting of smaller events, I don't think that would account for an increase in reporting the 4-5 magnitude events.

So were still looking at an unusual amout of medium sized quakes, without much indication as to what it might lead too yet.

[dgavin]

Another 4.5 on the South Gordo portion of Jaun de Fuca plate today.

[dgavin]

And another 4.2 quake today at the northern most interface of North America (Canada), Pacific and Jaun de Fuca plates.

[dgavin]

3 more quakes this week after a long peorid of quiet, 3.3, 3.6 and 4.4 magnitudes.

*edit to add*

Another quake today, 3.7 Mag.

[dgavin]

4 more Quakes, two today. 4.5 followed by a 4.8 on the norther edge of plate today, a 3.3 and 2.1 on the mid and south parts of plate ealier this week.

I finnaly found out that the seemingly sudden appearence of these quakes and continuing frequency of them, is due to the recent installation of ocean based Siesmographs. On average Jaun De Fuca has around 600 quakes a year, typically 3 of which are over 5.0 magnitude. Before this year they were only detected through Hydrophones left in operation after the last war (WW2) so the data was only availabe through US Navy channels.

So now we have real time ocean based Siesmographs in operation now, and seeing the results of that.

[dgavin]

Nothign to worry over, but just an FYI.

Toady at 8pm Pacific Time, many siemographs from nothern Calif, to southern Canada picked up a slow/slip tremor signature of the Jaun-de-fuca Subduction zone. The strogest readings were from the Mid. Oregon stations.

These do happen occasioanly, but this is the first time I've seen this happen since I started watching webicorders. The wave forms had a frequency span measuring in the 30's of seconds. Nice to finaly catch one of these types of background events.

[grapes]

Still reading. :)

[Ara Pacis]

Is this the location from which the infamous 1700 Cascadia subduction zone megathrust earthquake and tsunami originated?

[dgavin]

Ara,

My method of location is a bit rough and based more on signal stregths and arrival times, then on the proper methods (As i'm not trained well enough in those fomulas yet). The strongest signals were alost directly below 3 Sisters and Newberry calder areas, while the arrival timing puts it bit more towards the coastal region of Oregon.

So if i'm not to far off, it is south of the 1700 event which occured mostly along the washington coast.

[dgavin]

Besides the Mt. Axial activity along the Jaun De Fuca ridge, there was a 3.6 quake off the coast of Eureka, Calif., and a 4.3 just off shore of the calif/oregon border.

I'd almost have to say these are follow up events to the slow slip event from Mar 24th.

It's been quiet on the plate for a number of months, and then activity picks up again just after the slow/slip event. The quakes are all located at the spreading/transform boundries between pacific plate, and Jaun De Fuca plate. This also makes some sense if the slow/slip process reduces enough stress, then the spreading of the Jaun De Fuca ridge will be less impeeded.

[dgavin]

June 18th a 4.8 and a 4.2 about 1 - 5km's from the rift zone.

Today a 3.8 along the mid plate transfrom zone.

[dgavin]

Today (Sat Feb 4th) there was a 2.6. Quake off the Oregon Coast at 11 am, followed by a 4.3 near by that at 11:30am and then a 5.7 Quake at 12 noon, off the coast of Washington/Canada.

The 5.7 seems to be a standard Strike/Slip fault, the others have no movement tensors posted yet.

[Tensor]

... have no movement tensors posted yet.

Not surprising, I've been ill and spend most of the day in bed, so yeah, no movement here.:p :D

[dgavin]

Not surprising, I've been ill and spend most of the day in bed, so yeah, no movement here.:p :D

:doh:

[dgavin]

A small 2.2 micro earthquake today, off oregon southern coast. Thats 4 quakes this week so far on the Jaun De Fuca plate. Nothing untoward about this activity though.

This was a nice one to look at in that it showed up on a number of broad band and volcano's seismographs, in spite of it's small magnitude. Noticed it first on Newberry/Pine Mountain stations, and can even follow and the see the signal arriving earlier the closer to SW coast stations are.


As far as Tensor movement goes, hopfully our Tensor is up and moving around again:p

[dgavin]

Late updates: On Sat Feb 4th there was an additional 4.8 Mag. quake near the 5.7 area. and a 3.0 quake near the 4.3 one on the pacific plate side of the Jaun De Fuca ridge. 6 Quakes total.

[dgavin]

Another quake reported late, on feb 7th, magnitude 3.4 directly on a part of the rift area, this one half way between the 4.3 and 3.0 from saturdays quakes.

And yesterday another 3.0 at the southmost part of the Jaun de Fuca rift off california coast, this one only at a depth of 600m (has not been reviewed yet though). Considering it's depth, this might be related to a hydrate release. It had a very -short- duration, 22 seconds, and there was no precursor P wave identifiabale (the webicorders may not be sensitive enough to see that though)

8 quakes total now.

[dgavin]

Another 3.0 just posted from jan 9th, near the other one and close to the same time. This one appears to be a normal strike/slip along the rift. 9 total now, still counting.

[dgavin]

Last night, 7:30 PST Valentines quake coming in at a 6.0 mag along the Jaun de Fuca Ridge.

[dgavin]

USGS posted five more older events from Jaun de Fuca, a 4.5 and 4.2 up by Canada, two 3.0’s at the southern edge, and a 2.5 just off shore from Lincoln City, OR.

Count for this week now at 6 quakes, with one strong.
Last two weeks total now upto 15 quakes.

At this point this is just slightly higher then the average amount of activty on Jaun de Fuca, but it's not anything significant to worry about.

[Sticks]

Name of thread changed to Jaun de Fuca Plate Activity

[dgavin]

Thanks Sticks!

Another 2.1 today about 80km from Depot Bay near the subduction region itself.

[Gillianren]

So we've introduced a misspelling into the thread title? It's Juan. Not "Jaun." It's the Spanish for "John."

[Swift]

So we've introduced a misspelling into the thread title? It's Juan. Not "Jaun." It's the Spanish for "John."
:eek:

Everyone clap hard and think of their happy spelling thoughts....http://oi39.tinypic.com/o6h3r7.jpg

[Trebuchet]

So we've introduced a misspelling into the thread title? It's Juan. Not "Jaun." It's the Spanish for "John."

As long as it didn't become "San Juan de Fuca", which is all too common, I'm happy.

[Gillianren]

Right. Two different guys. (Actually, there are a lot of San Juans. But you know what I mean.) Though the Wikipedia page on Juan de Fuca is more interesting than I would have expected.

[dgavin]

Two Aftershocks from the 6.0 added to USGS from prior days activity, a 2.1 and a 2.7. Weekly Count up to 9 again.

The reason these are sometimes delayed, is the Juan de Fuca plate seismographs are not on the list of stations that automatically post events. I asked a local Geologist that works for our Trasportation Dept. here about the delay on these.

So the smaller the event, the more delay there is before a Seismologist gets to it.

[dgavin]

Updates to last weeks activity: Another 4.7 near canada coast, and a 3.1 southern mid-plate.
Two week total: 18 with 1 mag 6.0

This week so far:
3.0 magnitude along subduction area off N. California, 3.4 aftershoock in the region of the prior weeks 6.0.

[dgavin]

A small quake yesterday, 2.7 off the southern oregon coast.

Total events at 21 so far, with an appearent slowing trend last week.

[dgavin]

Two small quakes today, 2.7 and a 2.8 west of Newport in the subduction region.

[dgavin]

No additiona quakes list week, other then the noted 2.

A 3.1 EQ this moring just off the coast west of Newport. Same region as last weeks events.

[dgavin]

A 4.1 EQ 2am this morning on the southern area of the Rift Zone, it Doesn't appear to be volcanic.

[dgavin]

This moring starting just after 1:30am PDT, a micro-swarm of Earthquakes occured on Jaun De Fuca plate along the Subduction region just off the coast of Newport Oregon. Quake's registered in at 3.2, 3.7, then 3.1, at about 30km depth, then the swarm immediately stoped.

I can't really say what this is, as I haven't seen such a small number of quakes in a swarm before, with magnitudes over 1.8. This swarm is around the estimated depth of the Jaun-der-Fuca/Pacific junction area however, so I suspect these were not Strike/Slip quakes, but Lateral/Slip quakes. No movement solutions were posted for them yet, so thats only a guess.

[Trebuchet]

As long as they don't send a major tsunami up the actual Strait of Juan de Fuca, I'm good with that. I spend way too much time looking out at it and wouldn't want any unpleasantries.

[dgavin]

Another 1.9 over the weekend, and just a few (11:04am PDT) minutes ago, an unspecified Mag quake that showed on almost all Oregon siemographs, with Reedssport being the closest one to the quake. This isn't even posted to the auto events yet. Soon as i find out mroe i'll post a followup.

[dgavin]

And just a few (11:04am PDT) minutes ago, an unspecified Mag quake that showed on almost all Oregon siemographs, with Reedssport being the closest one to the quake. This isn't even posted to the auto events yet. Soon as i find out mroe i'll post a followup.

It was a preliminary 6.0 quake 500 miles offshore of Acapulco, Mexico, on the Pacific Rift, 9.9 km deep. Scratch this one of the Jaun-de-Fuca list:)

[dgavin]

Not to be left out, the was a 4.4 mag quake last night on the Juan De Fuca ridge, due west of Coos Bay Oregon.

[Gillianren]

Juan. And Coos Bay.

[dgavin]

2 aftershocks so far from the 4.4 event, both registering 2.1 magnitude.

[dgavin]

There was a 5.9 Quake along the Juan-de-Fuca Ridge (Slip) area, off the Oregon coast, west of Brandon, OR, about 2 hours ago.

This puts the amount of strong quakes at 1 over the normal yearly average. I have no additional comments yet on that little fact.

[Trebuchet]

I think that would be Bandon (http://en.wikipedia.org/wiki/Bandon,_Or), not Brandon. Home of one of my favorite little lighthouses (http://en.wikipedia.org/wiki/Coquille_River_Light). Which I see they've at least partially painted since we were there.

[dgavin]

So far 3 aftershocks to the 5.9 Quake, off the coast of Bandon Oregon, last weeks aftershocks were 2.6 and 2.8. This mornings was a 3.4.

[dgavin]

2 More quakes since yesterdays report. Both along the subduction region this time, a 4.1 Mag near Eureka, CA and a 2.8 Mag near Newport, OR.

[dgavin]

4.1 Mag Yesterday near northern edge offshore of Canada

[dgavin]

Busy week for Juan de Fuca plate.

The 4.1 in prior post the offshore Canada quake was updated to a 4.4, and there were 3 subsequent evens in same region, 3.9, 4.0 and 4.4 magnitudes.

At the otherside of the plate off shore of California, there was a 2.5, 3.0 and a 3.8 mag.

[dgavin]

So far since last report

2 more quakes off shore of Canada, in same region as others, a 4.5 mag and a 4.0 Mag.

Off shore of california another 3.8 mag quake.

[dgavin]

After quite some time of quietness, there have been four events this week. A 5.1 and a 5.2 earthquake along the southern plate edge, off of california's coast, and a 4.1 and a 4.2 in the mid plate slip flault zone, off the oregon coast.

[dgavin]

Starting on the 29th, there has been what now qualifies as a small earthquake swarm, on the subduction region about 20-30km off shore of Gold Beach, Oregon

2.9 34km SW of Gold Beach, Oregon 2012-08-02 00:00:44 42.204°N 124.746°W 21.9
2.6 29km SW of Gold Beach, Oregon 2012-08-01 10:59:38 42.235°N 124.693°W 0.0
2.8 31km SW of Gold Beach, Oregon 2012-08-01 07:15:17 42.228°N 124.718°W 4.8
2.2 29km SW of Gold Beach, Oregon 2012-08-01 04:30:45 42.210°N 124.665°W 0.0
2.1 26km SW of Gold Beach, Oregon 2012-08-01 03:03:05 42.223°N 124.627°W 0.1
1.9 28km SW of Gold Beach, Oregon 2012-08-01 02:15:17 42.196°N 124.627°W 18.3
2.2 26km SW of Gold Beach, Oregon 2012-08-01 01:00:50 42.241°N 124.649°W 0.0
2.5 27km SW of Gold Beach, Oregon 2012-08-01 00:34:29 42.238°N 124.670°W 0.0
3.0 30km SW of Gold Beach, Oregon 2012-07-31 23:53:11 42.220°N 124.687°W 21.9
2.1 27km SW of Gold Beach, Oregon 2012-07-31 09:13:10 42.234°N 124.653°W 0.0
1.6 25km SW of Gold Beach, Oregon 2012-07-30 11:47:42 42.236°N 124.629°W 0.0
1.6 24km SW of Gold Beach, Oregon 2012-07-29 14:35:59 42.249°N 124.620°W 0.1
1.6 23km SW of Gold Beach, Oregon 2012-07-29 11:34:08 42.257°N 124.618°W 0.0
2.1 26km SW of Gold Beach, Oregon 2012-07-29 09:30:48 42.239°N 124.654°W 0.0

[dgavin]

This week three quakes so far, a 4.3 mag in the same location as the swarm two weeks ago. Plus a 4.5 and a 4.9 along the midplate-slip zone of the Jaun-de-Fuca rift area.

[dgavin]

Moderate Quake, plus two aftershocks on the 19th. A 5.5 Mag just off northern most washingtons coast. Followed by a 3.1 and then a 4.2 aftershook.

[dgavin]

Another aftershock this morning, 4.1 magnitude. All four events so far this week have been at 10km depth.

[dgavin]

Moving to a monthly report on this thread. 36 Jaun de Fuca/Cacadia Subduction Earthquakes this last month, three of them coming in at the 4.1 -4.5 magnitude range.

[Ara Pacis]

A question: I'm curious to know if any geologists have used strata along the shores or bathymetry to determine the angle of the NA plate in relation to the subducting plate to get an idea of how stressed it might be and how close it may be to snapping back.

[grapes]

A question: I'm curious to know if any geologists have used strata along the shores or bathymetry to determine the angle of the NA plate in relation to the subducting plate to get an idea of how stressed it might be and how close it may be to snapping back.The earthquakes themselves can pretty much map that out, way deeper than bathymetry or strata, and more accurately--however not good enough to make any sort of stress calculations or timing predictions, which are mostly based on historical data, IIANACI.

[Ara Pacis]

The earthquakes themselves can pretty much map that out, way deeper than bathymetry or strata, and more accurately--however not good enough to make any sort of stress calculations or timing predictions, which are mostly based on historical data, IIANACI.

I'm not sure I follow, nor do I know what IIANACI means. I'm referring to bending stress. When the Japanese earthquake happened last year, parts of Sendai alongthe coast subsided and were inundated (before the tsunami hit), while the portion of plate near the subduction fault snapped upwards. So, it's like a portion of the crust did a seesaw motion along some pivot line. I was wondering if we have historical data that we can look at angle that the crust is deforming and how close that angle is to historical maxima which is relaxed via an earthquake.

[dgavin]

Ara,

Yes there has been investigation in the strata along the NW coast lines, indicating about a once per 700 year time frame for cosatal inudation due to subsidence after a likely megathrust EQ event.

This is what led to the seperate thread I made, about a major Oregon EQ actualy being predicted over the next few decades.

The native american legends about a mythical "Thunderbird", are now thought to be related to stories about these huge plate altering earthquake events. The times of these legends that are datable, seem to roughly coincide with the strata evidence of the megathrust events.

From the Strata evidence, there are some low lying area's along the coast that would likely be underwater after such an event. This may possibly include most of Pacific City and Beverly Beach state park, along with parts of Astoria, Lincoln City, Newport, Coos Bay, and Depot Bay.

[Ara Pacis]

Ara,

Yes there has been investigation in the strata along the NW coast lines, indicating about a once per 700 year time frame for cosatal inudation due to subsidence after a likely megathrust EQ event.

This is what led to the seperate thread I made, about a major Oregon EQ actualy being predicted over the next few decades.

The native american legends about a mythical "Thunderbird", are now thought to be related to stories about these huge plate altering earthquake events. The times of these legends that are datable, seem to roughly coincide with the strata evidence of the megathrust events.

From the Strata evidence, there are some low lying area's along the coast that would likely be underwater after such an event. This may possibly include most of Pacific City and Beverly Beach state park, along with parts of Astoria, Lincoln City, Newport, Coos Bay, and Depot Bay.

Right, but is that only related to periodicity or to an angular deviation from zero level?

[dgavin]

The strata evidence all seems to point to the periodicity of megathrust or larger quakes. Andd there seems to be some variences in how often.

The follow URL repost from another thread, I think will answer some of your questions about strata evidence and quakes.

http://www.pnsn.org/outreach/earthquakesources/CSZ/turbiditeevidence

[Ara Pacis]

The strata evidence all seems to point to the periodicity of megathrust or larger quakes. Andd there seems to be some variences in how often.

The follow URL repost from another thread, I think will answer some of your questions about strata evidence and quakes.

http://www.pnsn.org/outreach/earthquakesources/CSZ/turbiditeevidence

Nope. It doesn't even touch on tilt.

[dgavin]

Catching up here.

On October 28th a Large 7.8 Mag just north of the Juan De Fuca edge. Listing all events upto today.

M Location UTC Lat Lon D-km
4.1 165km SSW of Masset, Canada 2012-11-07 15:04:23 52.649°N 133.085°W 10.0
4.0 158km SSW of Masset, Canada 2012-11-06 15:47:13 52.717°N 133.062°W 10.0
4.6 194km SSE of Masset, Canada 2012-11-06 10:27:03 52.335°N 131.305°W 10.2
4.6 167km S of Masset, Canada 2012-11-04 18:27:19 52.522°N 132.346°W 20.3
4.9 186km S of Masset, Canada 2012-11-04 12:27:36 52.339°N 132.031°W 10.4
4.1 142km S of Masset, Canada 2012-11-04 07:42:15 52.741°N 131.859°W 10.0
4.0 156km S of Masset, Canada 2012-11-04 05:07:53 52.617°N 131.957°W 10.0
4.2 165km S of Masset, Canada 2012-11-03 17:49:14 52.535°N 132.007°W 22.4
4.0 187km SSW of Masset, Canada 2012-11-03 12:18:42 52.380°N 132.751°W 9.8
4.0 157km S of Masset, Canada 2012-11-03 09:48:24 52.611°N 132.378°W 10.1
4.4 166km S of Masset, Canada 2012-11-03 04:25:19 52.522°N 131.870°W 12.8
4.0 203km S of Masset, Canada 2012-11-02 08:37:10 52.186°N 132.160°W 10.4
4.5 182km S of Masset, Canada 2012-11-02 08:19:59 52.379°N 132.025°W 10.2
4.2 170km S of Masset, Canada 2012-11-02 07:15:45 52.497°N 131.759°W 11.0
4.9 161km S of Masset, Canada 2012-11-01 03:16:00 52.564°N 131.943°W 10.3
5.1 181km SSE of Masset, Canada 2012-11-01 03:15:23 52.500°N 131.100°W 1.0
4.0 165km S of Masset, Canada 2012-10-30 17:33:29 52.535°N 132.323°W 1.8
4.6 192km S of Masset, Canada 2012-10-30 14:10:59 52.285°N 131.948°W 10.0
4.7 208km S of Masset, Canada 2012-10-30 04:40:15 52.170°N 131.604°W 10.2
5.0 199km S of Masset, Canada 2012-10-30 02:55:08 52.222°N 132.116°W 19.2
6.2 210km S of Masset, Canada 2012-10-30 02:48:58 52.129°N 132.320°W 18.6
4.1 179km S of Masset, Canada 2012-10-30 00:35:09 52.423°N 131.655°W 10.0
4.0 166km S of Masset, Canada 2012-10-30 00:32:18 52.526°N 131.936°W 10.0
4.3 158km S of Masset, Canada 2012-10-29 22:00:33 52.593°N 132.273°W 10.0
4.6 188km SSE of Masset, Canada 2012-10-29 20:49:49 52.366°N 131.459°W 26.5
4.1 198km S of Masset, Canada 2012-10-29 16:33:08 52.231°N 131.971°W 10.0
4.0 216km S of Masset, Canada 2012-10-29 15:38:29 52.074°N 132.137°W 10.0
4.0 225km S of Masset, Canada 2012-10-29 15:15:02 51.989°N 132.225°W 10.0
4.0 224km S of Masset, Canada 2012-10-29 15:01:06 52.013°N 131.757°W 10.0
4.4 163km S of Masset, Canada 2012-10-29 12:05:14 52.574°N 132.552°W 10.2
4.1 119km S of Masset, Canada 2012-10-29 06:03:52 52.959°N 132.377°W 3.3
4.1 173km S of Masset, Canada 2012-10-29 03:47:55 52.461°N 132.190°W 10.0
4.0 182km S of Masset, Canada 2012-10-29 02:40:53 52.396°N 132.502°W 10.0
4.6 165km S of Masset, Canada 2012-10-29 01:49:02 52.530°N 131.965°W 10.0
4.3 184km S of Masset, Canada 2012-10-29 00:26:49 52.358°N 132.096°W 10.0
4.0 174km SSE of Masset, Canada 2012-10-29 00:18:50 52.612°N 130.948°W 10.0
4.1 126km SSE of Masset, Canada 2012-10-28 23:55:02 52.978°N 131.333°W 10.0
4.7 161km S of Masset, Canada 2012-10-28 23:34:23 52.570°N 132.291°W 10.0
4.9 144km S of Masset, Canada 2012-10-28 23:26:50 52.733°N 132.436°W 10.0
4.2 158km S of Masset, Canada 2012-10-28 23:11:17 52.608°N 132.454°W 12.5
4.7 189km S of Masset, Canada 2012-10-28 22:41:28 52.316°N 131.904°W 10.0
4.6 158km S of Masset, Canada 2012-10-28 21:38:19 52.602°N 131.893°W 24.7
5.1 166km S of Masset, Canada 2012-10-28 19:16:55 52.544°N 132.580°W 47.2
5.5 190km S of Masset, Canada 2012-10-28 19:09:56 52.315°N 131.860°W 14.8
5.4 151km SSW of Masset, Canada 2012-10-28 19:03:24 52.742°N 132.902°W 32.8
6.3 177km SSW of Masset, Canada 2012-10-28 18:54:16 52.480°N 132.793°W 20.0
4.3 169km SSE of Masset, Canada 2012-10-28 16:17:03 52.537°N 131.508°W 10.0
4.6 140km SSW of Masset, Canada 2012-10-28 15:59:11 52.786°N 132.595°W 10.0
4.4 161km SSW of Masset, Canada 2012-10-28 15:57:15 52.638°N 132.866°W 10.7
4.4 177km S of Masset, Canada 2012-10-28 15:48:45 52.427°N 132.261°W 10.0
4.4 191km S of Masset, Canada 2012-10-28 15:44:59 52.309°N 132.408°W 10.0
4.0 185km SSE of Masset, Canada 2012-10-28 15:42:21 52.404°N 131.422°W 10.0
4.3 135km S of Masset, Canada 2012-10-28 15:24:22 52.803°N 132.113°W 10.0
4.0 166km S of Masset, Canada 2012-10-28 15:10:34 52.516°N 132.066°W 10.0
4.4 178km S of Masset, Canada 2012-10-28 15:06:55 52.417°N 132.169°W 10.0
4.0 164km SSE of Masset, Canada 2012-10-28 14:14:28 52.588°N 131.440°W 7.7
4.2 154km S of Masset, Canada 2012-10-28 14:04:27 52.635°N 132.403°W 10.0
4.1 190km SW of Bella Bella Islands, Canada 2012-10-28 13:45:48 51.127°N 130.305°W 10.0
4.8 175km S of Masset, Canada 2012-10-28 13:09:14 52.445°N 131.842°W 10.0
4.1 127km S of Masset, Canada 2012-10-28 12:38:46 52.870°N 132.204°W 10.1
4.0 142km S of Masset, Canada 2012-10-28 12:18:00 52.750°N 131.769°W 10.0
4.1 161km S of Masset, Canada 2012-10-28 12:09:43 52.568°N 132.065°W 10.0
4.7 175km S of Masset, Canada 2012-10-28 11:53:21 52.438°N 132.201°W 10.5
4.8 180km S of Masset, Canada 2012-10-28 11:27:46 52.395°N 132.161°W 11.1
4.3 183km SSE of Masset, Canada 2012-10-28 11:17:22 52.400°N 131.566°W 10.6
4.0 172km S of Masset, Canada 2012-10-28 10:59:14 52.477°N 131.769°W 9.7
4.3 170km S of Masset, Canada 2012-10-28 10:50:32 52.484°N 131.945°W 10.3
4.7 157km S of Masset, Canada 2012-10-28 10:45:50 52.621°N 132.500°W 10.2
4.5 145km SSW of Masset, Canada 2012-10-28 10:23:09 52.753°N 132.678°W 10.2
4.3 171km S of Masset, Canada 2012-10-28 10:10:27 52.482°N 132.247°W 10.3
4.3 119km S of Masset, Canada 2012-10-28 10:04:37 52.948°N 132.285°W 10.0
4.1 127km S of Masset, Canada 2012-10-28 09:52:58 52.892°N 131.733°W 10.0
4.4 127km S of Masset, Canada 2012-10-28 09:45:39 52.886°N 132.392°W 10.2
4.4 221km S of Masset, Canada 2012-10-28 09:41:16 52.029°N 132.187°W 10.0
4.6 196km S of Masset, Canada 2012-10-28 09:36:36 52.258°N 132.343°W 10.3
4.4 173km SSE of Masset, Canada 2012-10-28 09:22:50 52.551°N 131.193°W 10.0
5.1 197km S of Masset, Canada 2012-10-28 09:17:27 52.243°N 131.996°W 10.0
4.2 215km S of Masset, Canada 2012-10-28 09:15:48 52.102°N 131.653°W 10.0
4.2 277km SSW of Masset, Canada 2012-10-28 08:47:38 51.634°N 133.314°W 10.0
4.3 216km S of Masset, Canada 2012-10-28 08:22:04 52.067°N 132.073°W 10.0
5.0 198km SSE of Masset, Canada 2012-10-28 07:25:22 52.270°N 131.493°W 10.6
4.9 140km S of Masset, Canada 2012-10-28 07:16:37 52.775°N 132.456°W 11.4
4.6 212km S of Masset, Canada 2012-10-28 07:12:14 52.109°N 132.221°W 10.0
4.4 231km S of Masset, Canada 2012-10-28 07:02:19 51.941°N 131.836°W 10.8
5.0 203km SSE of Masset, Canada 2012-10-28 06:16:53 52.268°N 131.212°W 11.5
4.5 139km SSW of Masset, Canada 2012-10-28 05:51:17 52.815°N 132.714°W 10.3
4.3 181km SSE of Masset, Canada 2012-10-28 05:47:08 52.430°N 131.451°W 10.1
4.1 248km S of Masset, Canada 2012-10-28 05:38:38 51.786°N 132.312°W 10.1
4.3 211km S of Masset, Canada 2012-10-28 05:21:36 52.140°N 131.571°W 10.0
4.3 169km S of Masset, Canada 2012-10-28 05:15:12 52.499°N 132.222°W 10.1
4.5 178km S of Masset, Canada 2012-10-28 05:02:49 52.409°N 132.165°W 10.3
4.3 180km S of Masset, Canada 2012-10-28 04:54:46 52.403°N 132.439°W 10.1
4.7 155km SSW of Masset, Canada 2012-10-28 04:41:05 52.648°N 132.597°W 20.0
4.6 140km SSW of Masset, Canada 2012-10-28 04:33:51 52.906°N 133.120°W 10.0
5.1 254km SSW of Masset, Canada 2012-10-28 04:25:17 51.930°N 133.642°W 20.0
4.8 183km S of Masset, Canada 2012-10-28 03:52:25 52.372°N 131.823°W 20.0
5.8 154km S of Masset, Canada 2012-10-28 03:14:10 52.629°N 132.243°W 10.0
7.8 141km S of Masset, Canada 2012-10-28 03:04:09 52.742°N 132.131°W 20.1

[dgavin]

Another large event, this time on the Cocos Subduction region, Posting this here as the Cocos Plate and Juan de Fuca plate were once the same plate (Fallon Plate) and likey once were part of the same subduction zone.
M Location UTC Lat Lon Dkm
7.4 24km S of Champerico, Guatemala 2012-11-07 16:35:50 14.083°N 91.916°W 41.6

According to Reuters


The quake was also felt in El Salvador and more than 750 miles away in Mexico City, where some office workers were also briefly evacuated. Mayor Marcelo Ebrard said the quake was felt strongly in a large part of the city of 20 million people.

[dgavin]

A moderate one, 6.3 mag off vancover island last evening at 6pm

[dgavin]

A Minor quake, 3.2 mag below NW Portland this morning at 6:15 am

[dgavin]

A 6.0 quake about 250km north of the Juan de Fuca plate this week.

The Tsunami warning issued from the 8.0 EQ south of Solamon Is. last night was canceled early this morning. The largest Tsunami wave recorded form that quake was only 1.5 feet (4.4 dm)