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Cascade Volcanoes and Cascadia Subduction Zone

  1. Jul 16, 2016 #1


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    Since we often get comments on US Volcanoes, particularly those in California, Oregon and Washington State, I thought it would be worthwhile to have a separate Cascade Volcano thread.

    USGS has a Cascade Volcano Observatory.

    There is also a site on volcanoes.

    The Eruption History of Mount Rainier

    U.S. Volcanoes and Current Activity Alerts

    I've read reports of geothermal activity around Mt. Rainier. I haven't seen any in person, but I hope to visit more often.

    Someone took a video of steam plumes near the top.

    There is an active monitoring program at Mt. Rainier and at Mt. St. Helens. I don't know much about the other volcanoes.

    There is a separate thread about Mt. Hood.

    Some background on the Cascadia Subduction Zone
    http://earthquake.usgs.gov/data/crust/cascadia.php [Broken]

    See also -
    The orphan tsunami of 1700—Japanese clues to a parent earthquake in North America
    Professional Paper 1707
    Last edited by a moderator: May 8, 2017
  2. jcsd
  3. Jul 17, 2016 #2
  4. Jul 17, 2016 #3
    There doesn't appear to be a lot of current info on activity of the Garibaldi volcanic complex in Canada.
  5. Jul 17, 2016 #4
  6. Jul 17, 2016 #5
    Thanks again, Astronuc.
  7. Jul 17, 2016 #6
  8. Jul 17, 2016 #7


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    There does seem to be a lack of information on the Garibaldi Volcanic Complex.

    There is a Wikipedia article, which describes the Garibaldi Volcanic Belt as a continuation of the Cascades.

    According to that section, "at least four volcanoes have had seismic activity since 1985, including Mount Garibaldi (three events), Mount Cayley (four events), Mount Meager (seventeen events) and the Silverthrone Caldera (two events). Seismic data suggest that these volcanoes still contain active magma chambers, indicating that some Garibaldi Belt volcanoes are likely active, with significant potential hazards."
    One of the references seems to no longer exist, but it is available on the Wayback Archive - http://wayback.archive.org/web/20061008200258/http://gsc.nrcan.gc.ca/volcanoes/gscvol_e.php

    I looked at the Natural Resources Canada website, but only found Earth Sciences - https://www.nrcan.gc.ca/earth-sciences

    It seems that they have reduced the program on volcanoes - http://chis.nrcan.gc.ca/volcano-volcan/index-en.php

    Earthquakes has a bit more - http://www.earthquakescanada.nrcan.gc.ca/index-en.php

    It might be worthwhile for those in Canada to contact the institution and see if they would reinstate the volcanoes portion of the site.
    Geological Survey of Canada, Strategic Plan 2013-2018
  9. Jul 17, 2016 #8
    The survey plan mentions an agency and a program but no real plan to study the volcanoes in BC.

    The Canadian Hazard Information Service says, "In Canada, there is no ongoing monitoring at individual volcanoes because eruptions are so infrequent. However, Natural Resources Canada’s Canadian National Seismograph Network (CNSN) currently monitors volcanic regions in British Columbia and the Yukon and can detect very small earthquakes. If unrest were detected near a Canadian volcano, NRCan would respond by providing additional targeted monitoring of seismic activity, ground deformation, gas emissions, and other phenomena in order to find out what was happening, and would prepare hazard maps and work closely with emergency planning agencies to ensure that accurate hazard information was available. During the 2007 Nazko seismic swarm in central British Columbia, which lasted two months and did not lead to an eruption, NRCan installed additional seismic stations, took soil gas measurements to look for volcanic gas emissions, conducted field reconnaissance, and prepared a preliminary hazard map." http://chis.nrcan.gc.ca/volcano-volcan/how-comment-en.php

    Following the Seismograph Network link it shows only a few probes near the Garibaldi complex but only one actually in the Complex at Whistler mountain.
  10. Aug 6, 2016 #9


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    Some background on Lassen Peak in California.
  11. Aug 6, 2016 #10


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    I have some familiarity with the five Washington volcanoes, having climbed all of them, in addition to Hood in Oregon, and Shasta and Lassen in California.

    Mt. Baker is the northern-most Washington Cascade volcano. In the 70s and early 80s Mt. Baker was emitting so much steam in that geologists were warning of potential mudslides in some of river valleys radiating from the mountain. In 1974 I remember standing on the summit of Mt. Shuksan, about six air miles from Mt. Baker, hearing the sound of the steam being vented. It sounded like a jet engine, even at that distance. Since then the activity as subsided considerably. The last time I was at the summit of Baker, it was still emitting steam, but in a greatly reduced amount.

    To the south is Glacier Peak. As far as I know, there is no monitoring of this peak. Its last eruption was about 1700.

    The remaining volcanoes are Mt. Rainier, Mt. St. Helens, and Mt. Adams, all of which have monitoring systems installed.
    When I climbed Mt. Adams about 1984, I saw a cabin at the top of the mountain that was used by sulfur miners back in the 1920s. They used pack mules to take the sulfur down to where it could be loaded into wagons. The discovery of large deposits of sulfur in the salt domes in Louisiana that could be extracted more easily caused the operations on Mt. Adams to cease. As you can see from the picture, the cabin is almost completely choked with snow.
    MtAdams 001.jpg
  12. Aug 7, 2016 #11


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    Great info, Mark, I always enjoy the personal experience side

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