Oregon - Off shore earthquakes, prelude to erruption?

topic posted Sun, April 13, 2008 - 12:51 PM by  BRad
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By JEFF BARNARD, Associated Press Writer
Sat Apr 12, 5:06 PM ET



GRANTS PASS, Ore. - Scientists listening to underwater microphones have detected an unusual swarm of earthquakes off central Oregon, something that often happens before a volcanic eruption — except there are no volcanoes in the area

Scientists don't know exactly what the earthquakes mean, but they could be the result of molten rock rumbling away from the recognized earthquake faults off Oregon, said Robert Dziak, a geophysicist for the National Oceanic and Atmospheric Administration and Oregon State University.

There have been more than 600 quakes over the past 10 days in a basin 150 miles southwest of Newport. The biggest was magnitude 5.4, and two others were more than magnitude 5.0, OSU reported.

On the hydrophones, the quakes sound like low thunder and are unlike anything scientists have heard in 17 years of listening, Dziak said. Some of the quakes have also been detected by earthquake instruments on land.

The hydrophones are left over from a network the Navy used to listen for submarines during the Cold War. They routinely detect passing ships, earthquakes on the ocean bottom and whales calling to one another.

Scientists hope to send out an OSU research ship to take water samples, looking for evidence that sediment has been stirred up and chemicals that would indicate magma is moving up through the Juan de Fuca Plate, Dziak said.

The quakes have not followed the typical pattern of a major shock followed by a series of diminishing aftershocks, and few have been strong enough to be felt on shore.

The Earth's crust is made up of plates that rest on molten rock, which are rubbing together. When the molten rock, or magma, erupts through the crust, it creates volcanoes.

That can happen in the middle of a plate. When the plates lurch against each other, they create earthquakes along the edges.

In this case, the Juan de Fuca Plate is a small piece of crust being crushed between the Pacific Plate and North America, Dziak said.

news.yahoo.com/s/ap/20080...quake_swarm
posted by:
BRad
Seattle
  • Unsu...
     
    say goodbye VBC- this location and services are not needed on this planet anymore.... i guess its goodbye to the west.. seems logical considering .... oh well god works in his own way, we cant stop that. none of us can.....creator creates, creator destroys what isnt needed...... be what creator needs or be washed away in the cleansing.
  • wow

    Mon, April 14, 2008 - 7:31 AM
    Very Interesting.... thanks for the Tip!
    • Re: wow

      Mon, April 14, 2008 - 10:16 AM
      Being that I was born and have lived in Oregon almost all of my life, I can honestly say that there are many volcano's in this area of the PNW. We have Mt. Bachelor, Crater Lake, Mt. Hood, the Sisters mountains........and not to mention that Central Oregon has many lava beds and buttes from previous eruptions. No negativity here, just an FYI. The volcano's have been acting up for a year or so now, and I wouldn't be suprised if something did happen.
      As discussed many other times in many other posts', no one really knows what the future holds for us. In my own personal vision that I was shown, the major, disasterous volcano to erupt in the US is the super volcano over Yellowstone, and even then it wasn't (in vision) as devestating as the scientists say it could be (in worst case senerio).
      • Re: wow

        Mon, April 14, 2008 - 11:51 AM
        I had a conversation a few days ago with someone. The thought popped into my mind, and so I began asking her what the experience of an earthquake is like. She had experienced a couple, and I have not. This is the first I'm hearing of these recent quakes. Curious....
  • I wonder if this is a prelude to the BIG Quake that is supposed to happen off the San Andreas Fault? In 2004 they also detected "mysterious tremors" off this fault: www.berkeley.edu/news/medi...lame.shtml and www.ktvu.com/station/3987857/detail.html

    I know they are concentrating on Volcanoes in the article but there are no notable Volcanoes in the Area.... could it be possible that the mini quakes are a sign that the Plate is slipping, a precursor to a big quake that is about to happen? It says, "The Earth's crust is made up of plates that rest on molten rock, which are rubbing together. When the molten rock, or magma, erupts through the crust, it creates volcanoes." But when the plates shift it creates Earthquakes and this shifting could be a sign that the Plate is about to give way. There obviously is alot of moevment going on.... with over 600 quakes in the past 10 days!? That is alot! of activity.

    The San Andreas Fault terminates where the Gorda Plate is found. The Gorda plate is located beneath the Pacific Ocean off the coast of northern California. Gorda Ridge is a "Tectonic Spreading Center" (a linear feature that exists between two tectonic plates that are moving away from each other. ) located off the coast of Oregon. It runs from a triple junction with the San Andreas Fault and the Mendocino Fracture Zone northward to another transform boundary, the Blanco Fracture Zone. To its east is the Gorda Plate, which together with the Juan de Fuca Plate to its north, is what remains of the once-vast Farallon Plate which has been largely subducted under the North American Plate. To its west is the Pacific Plate. Juan de Fuca Plate they say is what is being crushed right now possibly causing the Earthquakes being detetcted.

    I would say that this is something that should be watched. And I wonder if it has any link to the "Big Earthquake" that was predicted for BC last year.... which if it didn't happen then could possibly happen this year (April 2008)? www.cbc.ca/canada/briti...bc-quake.html

    They say though that the science of earthquake prediction is pretty inexact...No one could predict a month and day right now. And sadly media caption writers tend to cause fear with larger than life headlines and these kinds of miscommunications on "predictions" can be misleading. Their motivations are to “draw an audience and sell newspapers,” rather than accurate reporting. But inspite of the false flags created by the media, it would not be a bad idea to be prepared because I don't think they are kidding when they say 600 earthquakes have been detected. It is true.

    Too, the Juan de Fuca Ridge is a tectonic spreading center located off the coasts of the state of Washington in the United States and the province of British Columbia in Canada. In the article it mentions the Juan de Fuca Ridge being squashed and that it could be a precursor to a Volcanic eruption. Mount St. Helens is in washington right? It is active too isn't it.

    This certainly sparks my interest. I wish the article would explain more though. It is not very imformative. They never are. One always has to digg alittle to get to the real information. South of the Bay area is super active as well. Does anyone remember the swarm of quakes a month or two back down in the Salton Sea area of California? When one end of a massive fault zone (California) has a swarming event indicating earth movement, and then an area off the northern end of the same structures goes through another major swarming event like the one that's going on this weekend off Oregon, then the people in between might want to prepare for a major earthquake, even if it doesn't happen. I wonder if that is what the Oregon Civil Air Patrol are doing this weekend?

    The Oregon Wing of the Civil Air Patrol will be conducting a major area wide multi-scenario training exercise this weekend, with aircraft and ground teams operating out of the Aurora State Airport north of Salem. The exercise, which will focus on scenarios involving air search and rescue, will employ the use of at least six aircraft and over 50 personnel from around the state and will be operating from the CAP's Northern Command Center at the Aurora airport. This is a good thing.

    Three general classes of earthquakes are now recognized: tectonic, volcanic, and artificially produced. The tectonic variety is by far the most devastating, and such quakes pose particular difficulties for scientists trying to develop ways to predict them. The ultimate cause of tectonic quakes is stresses set up by movements of the 13 or so major and minor plates that make up the earth's crust (see Plate Tectonics). Most tectonic quakes occur at the boundaries of these plates, in zones where one plate slides past another—as at the San Andreas Fault in California, North America's most quake-prone area—or is subducted (slides beneath the other plate).

    Of the two classes of nontectonic earthquake, those of volcanic origin are seldom very large or destructive. They are of interest chiefly because they often herald impending volcanic eruptions, as they did in the weeks preceding the eruption of Mount Saint Helens, Wash., in May 1980. Such quakes originate as magma works its way upward, filling the chambers beneath a volcano.

    Humans can induce earthquakes through a variety of activities, such as the filling of new reservoirs, the underground detonation of atomic explosives, or the pumping of fluids deep into the earth through wells. There is also theories that Tesla was able to produce Earthquakes on the other side of the world with his inventions.

    But non-the-less its long been predicted that we are over due for a BIG earhthquake. I suppose they mean the "tectonic" kind.

    Shift Happens.
    Stay aware.
    Stay safe.

    xo



  • 5.2 earthquake rocks large area of Midwest; no major damage


    Apr 18, 11:59 AM (ET)
    By JIM SUHR


    WEST SALEM, Ill. (AP) - Residents across the Midwest were awakened Friday by a 5.2 magnitude earthquake that rattled skyscrapers in Chicago's Loop and homes in Cincinnati but appeared to cause no major injuries or damage.

    Dozens of aftershocks followed, one with a magnitude of 4.5.

    The quake just before 4:37 a.m. was centered six miles from West Salem, Ill., and 45 miles from Evansville, Ind. It was felt in such distant cities as Milwaukee, Des Moines, Iowa, and Atlanta, nearly 400 miles to the southeast.

    "It shook our house where it woke me up," said David Behm of Philo, 10 miles south of Champaign. "Windows were rattling, and you could hear it. The house was shaking inches. For people in central Illinois, this is a big deal. It's not like California."

    In West Salem itself, a chimney on one house fell and there were reports of cracks in walls. "We're very thankful we had no one injured," said Harvey Fenton, the town's police and fire chief.

    He was at first unsure what to make of the sudden rumbling when it woke him up.

    "A major shaking is the best way I can describe it," said Fenton, 58.

    Fifteen miles to the southeast, in Mount Carmel, a woman was trapped in her home by a collapsed porch but was quickly freed and wasn't hurt, said police dispatcher Mickie Smith. A century-old apartment building there, a former schoolhouse, was evacuated because of loose and falling bricks.

    Bonnie Lucas, a morning co-host at WHO-AM in Des Moines, said she was sitting in her office when she felt her chair move. She grabbed her desk, and then heard the ceiling panels start to creak. The shaking lasted about 5 seconds, she said.

    The quake is believed to have involved the Wabash fault, a northern extension of the New Madrid fault about six miles north of Mount Carmel, Ill., said United States Geological Survey geophysicist Randy Baldwin.

    The last earthquake in the region to approach the severity of Friday's temblor was a 5.0 magnitude quake that shook a nearby area in 2002.

    "This is a fairly large quake for this region," Baldwin said. "They might occur every few years."

    It was initially reported as a 5.4-magnitude earthquake, but the USGS later revised its estimate to 5.2.

    "This was widely felt, all the way to Atlanta, a little bit in Michigan," said USGS geophysicist Carrieann Bedwell.


    In Cincinnati, Irvetta McMurtry said she felt the rattling for up to 20 seconds.

    "All of a sudden, I was awakened by this rumbling shaking," said McMurtry, 43. "My bed is an older wood frame bed, so the bed started to creak and shake, and it was almost like somebody was taking my mattress and moving it back and forth."

    In Louisville, Ky., the quake caused some bricks to fall off a building near downtown. Television video showed them strewn in the street.

    In Chicago, officials were checking structures to ensure there was no damage. The quake also shook skyscrapers in downtown Indianapolis, about 160 miles northeast of the epicenter.

    The strongest earthquake on record with an epicenter in Illinois occurred in 1968, when a 5.3-magnitude temblor was recorded about 75 miles southeast of St. Louis, according the USGS. The damage was minor but widespread and there were no serious injuries.

    In 1811 and 1812, the New Madrid fault produced a series of earthquakes estimated at magnitude 7.0 or greater said to be felt as far away as Boston. They were centered in the Missouri town of New Madrid (pronounced MAD rid), 140 miles southeast of St. Louis.

    Experts say that with the much higher population in the Midwest, another major quake along the New Madrid fault zone could destroy buildings, bridges, roads and other infrastructure, disrupt communications and isolate areas.

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