What might be happening at Mt. Rainier?

Eruptions reader Doug pointed out in a recent comment that the seismicity at Mt. Rainier in Washington has increased over the last month or so. Take a look for yourself:

Mt. Rainier seismicity over the last year (8/2008 to 9/2009). Image courtesy of PNSN

Taking a closer look, over the last week there has been 7 earthquakes over the last 5 days – all between M1-3 – near Rainier, most calculated to be between 1.5 to 5.8 km depth.

Any thoughts? I see a lot more noise (earthquakes) between 3-6 km depth. It could as benign as seismicity due to fluid in the extensive hydrothermal system at Rainier or it might be magma moving up a level in the magma conduit … Interesting stuff to say the least …


  1. #1 theroachman
    September 21, 2009


    Is there a direct link to any webrecorders? Or to at least a snap shot of some of those quakes?

  2. #2 Erik Klemetti
    September 21, 2009

    roachman — You can check out all the “local” Rainier webicorders here:

    All you webicorder junkies, feel free to comment.

  3. #3 EKoh
    September 21, 2009

    Rainier is just excited about the upcoming GSA meeting in the region!

  4. #4 Zombie
    September 21, 2009

    I live in the Pacific Northwest and grew up in a small town on the Puyallup River, which is fed by melting snow and glaciers from Rainier and will apparently be the site of apocalyptic destruction should the mountain ever really go up in style. My Dad was a junior-high earth-science teacher, and enjoyed explaining such things. Good old Dad claimed Rainier was one of the most dangerous volcanos in the world in terms of the number of people living “down range” of a possible eruption.

    Dad was a real barrel of laughs that way.

    (My most vivid memory of those days was I think around July 1980 when St. Helens burped on a perfectly clear day, and I could see a huge and ominous mushroom cloud on the horizon.)

  5. #5 SHIRAKAWA Akira
    September 22, 2009

    A weekly update on Cascades volcano seismicity has been issued September 20 by CVO and apparently this is still within normal activity:


    Sunday, September 20, 2009 12:53 PDT (Sunday, September 20, 2009 19:53 UTC)

    Cascade Range Volcanoes
    Volcano Alert Level: NORMAL
    Aviation Color Code: GREEN

    Activity Update: All volcanoes in the Cascade Range are at normal levels of background seismicity. These include Mount Baker, Glacier Peak, Mount Rainier, Mount St. Helens, and Mount Adams in Washington State; Mount Hood, Mount Jefferson, Three Sisters, Newberry Volcano, and Crater Lake, in Oregon; and Medicine Lake volcano, Mount Shasta, and Lassen Peak in northern California.
    Mount St. Helens has been at Volcano Alert Level NORMAL (Aviation Color Code GREEN) since July 10, 2008.

    Recent Observations: A swarm of small, shallow earthquakes occurred beneath the summit of Mount Rainier on Sunday, September 20, 2009, starting at ~0920 PDT. According to the Pacific Northwest Seismic Network (PNSN), the largest event at 0945 PDT has a preliminary magnitude of M 2.2 with a depth of 1.8 km, located 1 km NNE of the summit. The swarm also featured many small events that were too small to be located, and lasted for several hours before gradually waning. Such swarms have happened several times in the past decade. One example is the swarm on November 7, 2004, that included a M 3.2 event. We consider the September 20, 2009, swarm to be within the realm of normal activity at Mount Rainier.

  6. #6 mike don
    September 22, 2009

    Thing is, Rainier doesn’t have to erupt to be dangerous, since there is the possibility -remote but possible- that a major debris avalanche/lahar could be triggered by a small phreatic explosion, or an earthquake in the immediate vicinity of the mountain. Not that I’m scaremongering, of course…

  7. #7 Ian
    September 22, 2009

    If it’s ranier, couldn’t the extra rain be affecting the electronics…?

  8. #8 volcanophile
    September 22, 2009

    So now, the next question si… what is this thing capale of doing?

  9. #9 doug
    September 22, 2009

    Sometime in the ’70s the east side of Rainier(on the flanks of Tahoma Rocks) experienced a sudden fload of hot water and rocks from under the glacier on the same side of the mountain that the current activity seems located. It happened during the winter and was not witnessed, but the effects of the outburst were obvious from the miles of damage, uprooted trees and debris downstream from the glacier. Smaller rocks were found on the roof of the White River gaurd station, over 10 miles downstream from where the event occured. I remember reading that some rangers visited the area of the outburst a week or so later and saw sheets of warm water still pulsing out from crevasses in the glacier, but I don’t recall seeing any photographs.

  10. #10 mike don
    September 22, 2009

    I have an interesting little book: “Mount Rainier: Active Cascade Volcano” (National Academy Press 1994, ISBN 0-309-05083-9) which gives an overview of the potential hazards. Mostly lahar/debris flow related, there have been some 46 identified lahars or glacier outflow floods since the last major event, the Electron Mudflow.

  11. #11 Erik Klemetti
    September 22, 2009

    I should have included this in the post, but here is the current USGS Hazard Map for Mt. Rainier showing the significant lahar hazards:

  12. #12 Müge Boz
    September 22, 2009

    Activity Update: All volcanoes in the Cascade Range are at normal levels of background seismicity. These include Mount Baker, Glacier Peak, Mount Rainier, Mount St. Helens, and Mount Adams in Washington State; Mount Hood, Mount Jefferson, Three Sisters, Newberry Volcano, and Crater Lake, in Oregon; and Medicine Lake volcano, Mount Shasta, and Lassen Peak in northern California.
    Mount St. Helens has been at Volcano Alert Level NORMAL (Aviation Color Code GREEN) since July 10, 2008.

    ı agree

    September 22, 2009

    I a’int no seismologist but the swarm has been going three days now. Pretty ominous signs if you ask me considering the well located earthquake map. Take a look at the cross section. Personally I find it very intriguing however feel the colour code should be raised a level. Due to the population that could be at risk…

  14. #14 MadScientist
    September 22, 2009

    Any deformations noticed by the satellite radar altimeters over the past few years?

  15. #15 denparser
    September 22, 2009

    It really erupt and hope no one get hurt.

  16. #16 Anne Jefferson
    September 22, 2009

    Slightly too the south, St. Helens had a nice avalanche this afternoon. Maybe they really are getting excited for GSA. :0

  17. #17 Doug C.
    September 22, 2009

    Evidently, Doug is a common name among Volcanophiles!The PNSN has some excellent web resources. A map of their Webicorders is here:

    Individual webicorder records are here:

    It looks like station RCS, which appears to be closet to the action is experiencing some anomalies. STAR looks noisy but the RCM station looks to have a pretty clear signal.

  18. #18 Stephen Tierney
    September 23, 2009

    Talking of Mt St Helen’s, I’ve been looking at the webicorders results for pre lava dome growth (2006). Its worth a look as similarities can be drawn. Could magma be rising up Rainers conduit?.. Mt st helens answered days and months later… The suspense is totally intriguing. I wonder how long it would take for any lava extrusion to penetrate the huge snowcap. Raniers activity page is informative, yet would like to see some tiltmetre evidence. Anybody know if this exist?

  19. #19 Smgumby
    September 24, 2009

    A lahar from Ranier would wipe out a BUNCH of us here in the area…

  20. #20 silentsnow
    September 29, 2009

    Keep in mind we live in a country where action is not taken until after an event happens. If one digs a little deeper into the USGS seismic activity at Ranier, there is an “Executive Statement” that reveals there has not been this level of seismic activity at Ranier in the 20 years that it has been monitored. The statement is ended in stating they are keeping a close eye on it. Here it is..

    “Executive Summary: A swarm of small earthquakes started on the morning of September 20, 2009, at about 09:00 PDT beneath Mount Rainier. To date, the swarm has consisted of hundreds of earthquakes, most occurring on Sept. 20. Most locate at a depth of 2-3 km (1-2 miles) beneath the northeast flank of the volcanic edifice, centered ~1 km (0.5 miles) northeast of the summit. The largest event was a M 2.3 on Sept. 20. As of Sept. 23 swarm events continue, but at a greatly reduced rate since early on September 22. Seismic swarms are concentrations of earthquakes that typically are not initiated with a mainshock, and are common features at volcanoes. The vast majority of volcanic swarms are not associated with eruptive activity. Rainier itself has had several such swarms: in the past 7 years there have been similar days-long swarms in 2002, 2004, and 2007, two of which (2002 and 2004 )included M 3.2 earthquakes. The Sept. 20 swarm has produced the largest number of events of any swarm at Rainier since seismic monitoring began over two decades ago, so we will continue to closely monitor seismicity and other geophysical parameters at Rainier.”

    I find it interesting and fascinating. Whether Ranier is gaining momentum to erupt again…time will tell.

  21. #21 Lee
    December 8, 2009

    I have been tracking Mt Rainier for nearly 3 months now and never have I seen this level of activity. I E-mailed the USGS 3 moths ago and they said for me to only to look at a specific web recording station. and that What I was seeing was the result of “Glacial Movement”.

    Now when some one redirects me and then tells me that it is glacial movement I get intrigued.

    I will say this though, the USGS did try to tell people about MT St. Hellens but they ignored them and thus the result were in the loss of life a few which were vaporized, a few that were buried, and a few lost in the muck an mire of the pyroclastic flow.

    But, now with all the junk going on in politics, I wouldn’t be surprised if this becomes the government’s answer to population control by not alerting.

    The other side, God gave us instincts and common sense..and a choice. Why do we need some one to tell us to leave? Why not just leave? What is the worst that could happen?

  22. #22 Stephen
    December 11, 2009

    Rainers showing a few quakes again today although shallow. Any meaningful interpretations? or just watch this space?

  23. #23 blahh
    December 21, 2009

    yeah. really

  24. #24 Anonymous
    October 10, 2010

    Mt. Rainier WILL blow in the next year or two

    the worst of it will happen if it blows during a bad winter, which it will most likely

    many people will die

  25. #25 julie
    November 17, 2010

    Mt Rainier is rotten inside and scientsts are worried one side will collapse in a land slide or it could erupt. no one should take this lightly. Look at yellowstone that is a bigger problem. I would tell any one if its going to erupt and scientists say so leave. Your live is more im portant than a house. Quake will swarm and get bigger and soner or later they will call for a eruption but right now they should not panic listen to the experts and the science un needly panic will cause lives to be lost.

  26. #26 Kali Rosek
    December 9, 2010

    I’m still learning from you, but I’m trying to achieve my goals. I certainly love reading everything that is written on your blog.Keep the tips coming. I liked it

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