Swarm of earthquakes detected off Oregon (600 in 10 days)

Update:
MAP 4.0 2008/04/13 22:44:26 43.746 -127.523 10.0 OFF THE COAST OF OREGON

More information on Seismic Activity in the Pacific Northwest

The Pacific Northwest is situated on the seismically active Pacific Ocean margin. Seismic activity in the Pacific Northwest is due to the convergence (or moving towards one another) of two tectonic plates, the North American Plate and the Juan de Fuca Plate. Extending from northern California to British Columbia, the Juan de Fuca Plate is being pushed underneath, or subducted by, the North American Plate at a rate of 40 to 50 millimeters per year (mm/yr). Additional seismic activity exists further offshore originating from the Pacific Plate and the Juan de Fuca Plate spreading apart from each other.

Cross section of the Juan de Fuca Plate subducting underneath the North American plate and the Pacific and Juan de Fuca Plates spreading apart from each other. U.S. Geological Survey.


This is about an earthquake swarm back in June 8, 1999:
Earthquake-induced changes in a hydrothermal system on the Juan de Fuca mid-ocean ridge

Hydrothermal vents on mid-ocean ridges of the northeast Pacific Ocean are known to respond to seismic disturbances, with observed changes in vent temperature1, 2, 3, 4. But these disturbances resulted from submarine volcanic activity; until now, there have been no observations of the response of a vent system to non-magmatic, tectonic events. Here we report measurements of hydrothermal vent temperature from several vents on the Juan de Fuca ridge in June 1999, before, during and after an earthquake swarm of apparent tectonic origin. Vent fluid temperatures began to rise 4–11 days after the first earthquake. Following this initial increase, the vent temperatures oscillated for about a month before settling down to higher values. We also observed a tenfold increase in fluid output from the hydrothermal system over a period of at least 80 days, extending along the entire ridge segment. Such a large, segment-wide thermal response to relatively modest tectonic activity is surprising, and raises questions about the sources of excess heat and fluid, and the possible effect on vent biological communities.

And another swarm in February 2005 (These older swarms look to be more north then the recent quakes):
Seismic Activity - Endeavour Ridge- February-March, 2005

Since Sunday morning 27 February at 0031Z, there has been an ongoing, intense earthquake swarm on the Endeavour segment of the northern Juan de Fuca Ridge. SOSUS has detected 3,742 earthquakes over a 5.5 day period. Event counts were as high as 50-70 per hour which is very similar in scale to past seafloor spreading events at Middle Valley in 2001 and Endeavour in 1999.

Geologic hazards of the Oregon coast

Written historic records from 1700 AD found in Japan confirmed geologic evidence that the Cascadia Subduction Zone can generate massive earthquakes.

reply to post by DearWife



Funny how the original poster said there were no volcanoes near by, when my first though was Mt.St.Helens, then I thought about the caldera at yellowstone.

Nice post, love the graphics.

I was reading about something similar to this article yesterday:
Earthquakes Along The Cascadia And San Andreas Faults May Be Linked, Affecting Risk To San Francisco Bay Region

ScienceDaily (Apr. 8, 2008) — Seismic activity on the southern Cascadia Subduction fault may have triggered major earthquakes along the northern San Andreas Fault, according to new research published by the Bulletin of Seismological Society of America (BSSA). The research refines the recurrence rate for the southern portion of the Cascadia fault to approximately every 220 years for the last 3000 years.

Cascadia subduction zone

reply to post by toasted


You might want to re-read my Original Post as I was only quoting the AP article that said "there are no volcanoes in the area". Never said I agreed with it. I suppose it depends on what your definition of how close means "in the area", and how close the volcano's would have to be to be related to the quakes or not.

I believe the article was insinuating that since there's no volcano's right on top of the epicenter of the quakes they were stumped as they're only use to seeing this type of activity in the immediate vicinity of active volcano's. My initial reaction was maybe they better take a better look at the ocean floor there as they might discover something new.

That's why I asked for comments from experts or at least those in the know here. I too first thought (secondary to an unknown volcano) of Yellowstone and the rest of our Northwest volcano's after learning of this swarm, especially Mount St. Helens which I personally watched erupt live in 1980 from my childhood home.

Though I have no professional training or formal education to back my beliefs, unlike most geologist I believe all seismic events around the planet are more related then we are led to believe. Maybe it's just because there's not enough evidence yet, for them or their professors to come to that conclusion. I believe eventually that may change, but that's just my personal WAG.

As far as this having anything to do with an unknown 2012 event as one poster mentioned, that's a pretty big reach. Though I suppose with the pole shift going on it wouldn't surprise me if we had an increase of seismic related activity due to this pole shift.

Thanks everyone for sharing your knowledge & time in this thread, especially my DearWife for taking the time to bring the graphics here.


[edit on 13-4-2008 by verylowfrequency]

reply to post by verylowfrequency


You sure know how to make a DearWife smile

Graphics do help with understanging things better, glad they were found and shared here for you all.

I was also thinking that it could be a new volcano forming like in the case of the new island in Tonga, but then there would be some evidence of pumice surfacing or gases. The link ressiv posted shows a Sea Surface Temperature graphic, which I also checked out on another website but the images state they're not availabe. They're the pics on the right under 3-day, click on either the 9km or 4km png (warning: huge graphics): SST [11 μ day] (Aqua-MODIS)

This is something interesting:
Storms uncover ancient 'ghost forest' along Oregon Coast

According to the article, the theory is that “around 2,000 years ago a massive, cataclysmic earthquake abruptly dropped this forest possibly more than 25 feet. Then, somehow, they [tree stumps] were preserved by sand and mud, rather then being destroyed and scattered, as natural erosion might've done… Either a tsunami brought the sand in or the earthquake rattled up so much soil and sand it covered the forest.”

Oregon Coast Show - Neskowin Ghost Forest


The Big One: Online Exhibit: Detective Story

Clue One: Ghost forests
Ghost forests—long-dead trees—stand stark along the coasts of Washington and Oregon. Atwater knew that similar stands of trees in Alaska had been killed after the Prince William Sound earthquake of 1964. He realized that the Alaskan quake had caused parts of the forest to drop below sea level. Tidewater had rushed in, drowning the trees. Over time, tidal mud accumulated and the area became a salt marsh and then a coastal meadow. But the dead trees still stood.

Hopefully there will be some news of what was found offshore with these recent quakes soon. A big yourwelcome to toasted and verylowfrequency on the graphics and thanks to the other posters for contributed to this thread as well. It's been a great learning experience. Think I'll retire now, hehe

Larger earthquakes only typically happen along or very close to major fault lines (dont think oregon is on one) but dozens of (perhaps not hundreds like this situation) small earthquakes do not indicate that a large earthquake is going to occur soon as kinetic energy is frequently being released.

In the case of Oregon, there are many faults, the subduction of the Juan de Fuca plate below the North American plate occurs just off the coast of Oregon, and historically this subduction zone sticks for a period of time and then slips generating some very large quakes (8+).

But what also happens as the crust subducts is remelting and volcanic activity that results, like that we saw with Mt. St. Helens. There has been an area of rising ground and earthquake swarms just east of the three sisters area, which indicates that it is likely a new volcano is forming there.

Like another poster here; I've had dreams all of my life with major re-working of the west coast and volcanic activity. I've also looked at the history of eruptions of pacific cascade volcanoes and it does seem when you look at the history that after one becomes active, such as St. Helens, that most of the other Pacific volcanoes do also within one hundred years, but Rainier is an exception to this; it appears to be quite independent.

The major subduction quakes haven't been marked by precursor swarms like this, this is more typical of volcanic activity, and given that there are other indications of same, I'm inclined to think that's what's happening.

[edit on 4/14/2008 by Nookster]

[edit on 4/14/2008 by Nookster]

Wow, i hope there's no tsunami from a large quake. They've happened
before...

Oregon Coast Tsunami

Thank you for the post. I've been watching the earthquake maps for a while now. I don't think people "in the area" should panic though. I'm in Portland and other than Mt. Tabor which is an extinct volcano, I don't think any of the volcanos are close enough to erupt on us.

If everyone would simply be aware, and watch for falling ash, we should be okay.

Id say its almost a necessity to learn about earthquakes and volcanos when you live in portland, or any part of the Pacific northwest which is close to lots of volcanos. One of which is still active (mt st helens) and the others, like Mt Rainier and Mt Hood are in active as of this time. Both are expected to blow at some point or another. Ive lived here for almost 11 years and have 11 years of studying geography and vulcanology(sp?) and evertything in between. For example, if you have ash falling, dont let it build up must more then a few inches or it'll collapse your roof. Afterall, it is pulverised rock! Needless to say, the swarm of quakes remind me so much of what Mt St Helens did before she started erupting again that in my opinion, I wouldn't be surprised if that boat comes back with gas and other measurements showing the movement of lava into a new volcano. I just hope that all of us here in Oregon are safe, and to remember, 3 days worth of food and survival tools is what they suggest for an earthquake or volcano, so all you peeps in the area, time to go shopping!

Im fascinated with volcanos and earthquakes, weird, I know, so this is a treat for me to see this in ATS!

Tela

reply to post by TwiTcHomatic



Your dream may come true April 20, 2008. That is the full moon date and full moons + increase in ocean pressures + tempurature deviation + an upcoming coronal hole activity zapping earths magnetic field maybe all that is needed to set off a big one.

The geomagnetic coronal hole effect fits wrangell76 observations of auroras and sesimic activity.

[edit on 14-4-2008 by WorldShadow]

and we add one more prediction to the zillions here on ats...

I really hope that doesnt happen on April 20th. No offense, but I hope you are wrong.

Originally posted by Telafree
Id say its almost a necessity to learn about earthquakes and volcanos when you live in portland, or any part of the Pacific northwest which is close to lots of volcanos. One of which is still active (mt st helens) and the others, like Mt Rainier and Mt Hood are in active as of this time. Both are expected to blow at some point or another. Ive lived here for almost 11 years and have 11 years of studying geography and vulcanology(sp?) and evertything in between. For example, if you have ash falling, dont let it build up must more then a few inches or it'll collapse your roof. Afterall, it is pulverised rock! Needless to say, the swarm of quakes remind me so much of what Mt St Helens did before she started erupting again that in my opinion, I wouldn't be surprised if that boat comes back with gas and other measurements showing the movement of lava into a new volcano. I just hope that all of us here in Oregon are safe, and to remember, 3 days worth of food and survival tools is what they suggest for an earthquake or volcano, so all you peeps in the area, time to go shopping!

Im fascinated with volcanos and earthquakes, weird, I know, so this is a treat for me to see this in ATS!

Tela

I lived in Seattle in the 1990's and experienced quite a few earthquakes. We were very much aware of the seismic risk thanks to the great public information campaigns. I have always had a feeling that Rainer may go in my lifetime. I am fairly certain that Mt. St. Helens will erupt again. I spent some time doing botanical field work at Mount St. Helens when I was there and that was an awesome sight. Nature is in COMPLETE control is the feeling you get when you see something like that. The other thing at MSH is the life coming back and how it survived and spread out from areas where birds would land and poop or areas that were covered by 5 feet of snow during the blast.

The swarms do sound like a volcano, at least that is what "they" always say. Life is full of suprises.

Here's an update from National Geographic

Richard A. Lovett
for National Geographic News

April 16, 2008
This weekend scientists will take to the water to try to puzzle out the cause of a "swarm" of mysterious earthquakes that has shaken the seafloor near Oregon in recent weeks.

About 600 earthquakes have been recorded in a small region about 190 nautical miles (350 kilometers) offshore from Yachats, said Robert Dziak, a geophysicist with Oregon State University and the National Oceanic and Atmospheric Administration (NOAA) in Newport, Oregon.

Colored dots show the earthquake "swarm" that struck waters off the shore of Oregon beginning in March 2008.

Scientists are now planning a marine expedition (black line) to help unravel what is causing the mysterious temblors, which were detected by a Cold-War-era system of underwater microphones originally designed to track Russian submarines.

This is from page 2:

The three-day research cruise, scheduled to begin on Friday, may solve some of these puzzles.

The scientists say they may find lava oozing out onto the seafloor or hot water percolating up from magma-heated undersea hot springs. They could also come across colder water squeezed out of the underlying crust by tectonic forces.

NOAA Vents Program

4/16/2008 Update:
A response cruise aboard the R/V Wecoma is scheduled to depart Newport, Oregon on Friday, April 18. Ship will be conducting CTD operations.

[edit on 16-4-2008 by DearWife]

reply to post by DearWife


Thanks again, DearWife. I'll look forward to the results of the 3 hour (day) tour. The weather started getting rough, the tiny ship was tossed....

Pretty cool that they have the resources to go out an do that so quickly.

Interesting sea floor picture as well.


[edit on 17-4-2008 by verylowfrequency]

Originally posted by verylowfrequency
reply to post by DearWife

 

Thanks again, DearWife. I'll look forward to the results of the 3 hour (day) tour.

The weather started getting rough, the tiny ship was tossed....

Pretty cool that they have the resources to go out an do that so quickly.

Interesting sea floor picture as well.


[edit on 17-4-2008 by verylowfrequency]

Your welcome

Here's an update of that map:

Figure 1: Map showing the earthquakes and planned response cruise track line. R/V Wecoma is scheduled to depart Newport, Oregon on April 20, 2008

And this is an audio interview with one of the marine geologists whose working on this along with a sound clip of what the instrument picked up:
Earthquake Swarm Worries Oregon

The Bryant Park Project, April 16, 2008 · Earthquakes began rumbling under the ocean off the Oregon coast two weeks ago. More than 600 have been recorded so far. Quakes do come in swarms, says marine geologist Bob Dziak, but not usually like this.

Listen Now


Earthquake swarm puzzles researchers

On the hydrophones, the quakes sound like low thunder and are unlike anything scientists have heard in 17 years of listening, Dziak said.

Or it could have just been karaoke night for them whales and dolphins messing with them hydrophones.

EDIT: had to had some laughter

[edit on 17-4-2008 by WalkOn]

hehe...yes, that could of very well been what those clicking sounds were that were mentioned on the audio clip. Never know.

Several more quakes today already. Maybe we can get a new island in a few years.

reply to post by _Del_


Looks to be magnitude 3's and 4's today.
Latest Earthquakes M3.0+ in the USA - Past 7 days

Here's an update from the NOAA Vents Program:

4/22/2008 Update:
CTD casts conducted at East Blanco Depression, Cascadia Depression (CD)and half-way between swarm center and CD. Although the realtime sensors on the CTD do not show any evidence of hydrothermal emissions from the seafloor, only shore-based measurements will provide definitive analyses of the water samples. Ship ahead of schedule allowing further CTD operations. Hydrophone will not be recovered on this expedition.

4/21/2008 Update:
Hydrophone deployed. At-sea analysis of CTD samples from the swarm site show do not show evidence of a hydrothermal plume. Conducting further CTDs at other nearby quake sites. View logbook from Bill Hanshumaker, educator at sea.

4/18/2008 Update:
Animation of earthquakes through time: (Quicktime *.mov).
Courtesy of Del Bohnenstiehl, North Carolina State University.