KF7TBA+K7LWA's Friday Insomniac-Net BLOG: 2015[20]A -- Ins-Net As for May 15, 2015_"Mount St. Helens: 1980 -- Part 2" [A-A-C]

Insomniac-Net ANSWERS -- Friday[20], May 15, 2015 [ A - A - C ]
Tonight's Topic: "Let's Get Ready to RUMBLE! -- Mount St. Helens: 1980 -- Part 2"
ANSWERS = [ A - A - C ]

    Good morning/evening, everybody! Thank you for joining us last night.
    We hope you discovered something interesting during the time we spent together on the Insomniac Net last night.
    Thanks to you all for playing along -- it was a lot of FUN for us. Hopefully, you had fun too!
        -- The ever-delightful Shelley [KF7TBA] and just plain old LW [K7LWA] (email K7LWA.INS@gmail.com).
    (Please Note: The Net Controller's Answers are always CORRECT (even if they aren't every time!)
   Please check out Winsystem's Insomniac Trivia Net page.
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    The trivia topic of our 12th Insomniac-Net of 2015 -- on March 20th -- was: "Let's Get Ready to RUMBLE! -- Mount St. Helens: 1980 -- Part 1".

     At that session, we asked you about the first stirring of this youngest Cascade Volcano as it re-awakened after 123 years of domancy (i.e., having no major eruptions).
    Tonight -- to mark the 35th Anniversary of Mount St. Helens' eruption next Monday -- we will once again be asking 3 questions about the eruption that occurred on May 18, 1980.
    On that morning, a magnitude 5.1 earthquake (less than a mile below the volcano) triggered a landslide on the bulging northern face of Mount St. Helens.

     That landslide -- the largest terrestrial landslide in recorded history -- reduced the summit by 1,300 feet (or about a 1/4 mile of mountaintop).
    That was followed by a lateral blast, ash eruption and fallout (called a "vertical eruption plume" soaring up 15 miles within the first 15 minutes), pyroclastic flows (intensely swift and hot mixtures of ash, pumice, rock-fragments, and gas), and lahars (also known as "debris mudflows").
    Mount St Helens erupted 6 more times in 1980 and sporadically through 1986, during which lava oozed out on the crater floor and began rebuilding the volcano's summit.
    During September 2004, Mount St. Helens re-awakened and continued to erupted for several years -- gradually rebuilding the summit (as it did many times in the past).
    Accordingly, how much more do you know about... one of the most dramatic geologic moments in American History?
   Please choose from any of the 3 (reuseable) answers of "A", "B", or "C" (if applicable!) for each questions listed below.
   Good Luck and remember YOU are always a WINNER with us, regardless of your actual answers!
    Wait, did you feel that? Oh, not to worry -- probably just Harry [ KD4JMV] driving by!

++ "Let's Get Ready to RUMBLE! -- Mount St. Helens: 1980 -- Part 2" ++
Question #1: At 8:32 AM(PST) on Sunday, May 18, 1980, while manning the Coldwater II observation post about 5 miles north of Mount St Helens alone, USGS volcanologist David Johnston radioed in to Headquarters "Vancouver, Vancouver. This is it..." before the lateral blast (traveling up to 700 mph) eradicated him and the surrounding area for 8 to 15 miles distance. How many seconds did it take for the blast to reach David?

        A. 40 seconds, or
        B. 90 seconds, or
        C. 120 seconds

Velocity: 225 - 730MPH
Since JRO is about 5 miles from the volcano and CRVC about miles, we can say something like: "Well, if you were standing here on the morning of May 18, 1980, and you saw the beginning of the lateral blast, you had about a minute left to live... (40 sec for JRO, 64 sec for CRVC)".
[MSH Volcano Hazards Workshop Handbook (Mt. St. Helens Eruptions V5.0) p11]

Question #2: The 1980-1986 and 2004-2008 eruption series added nearly 7% of the material (called "lava domes") needed to rebuild the summit to the height of the pre-1980 eruption. If these eruptions had continued, how many years would have been needed for Mount St Helens to regain those "missing" 1,300 feet of its original height?

        A. about 100 years, or
        B. about 1,000 years, or
        C. about 10,000 years

"At the start of 1990, the composite dome was about 3,480 feet by 2,820 feet in diameter and rose about 1,150 feet above the low point on the adjacent crater floor. It has a volume of about 97 million cubic yards, less than 3 percent of the volume of the volcano (about 3.5 billion cubic yards) removed during the landslide and lateral blast on May 18, 1980. If the dome resumes growth at its average rate of the 1980s (about 17 million cubic yards per year), it would take nearly a century to fill in the summit crater and more than 200 years to rebuild Mount St. Helens to its pre-1980 size".
NOTE: I misquoted the more correct answer of 200 years -- however, Answer A (about 100 years) is closest to the information cited above. -- K7LWA
[MSH Volcano Hazards Workshop Handbook (Mt. St. Helens Eruptions V5.0) p11]

Question #3: During our visit to the Cascade Volcano Observatory (CVO)'s May 2nd Open House, which activity did Shelley like the most?
        A. Posing for a picture of her picnicing in the Mount St Helens crater (with the aid of a USGS webcam and a "green screen" computer program), or
        B. Having a Mount St Helens "face decal" temporarily applied to her right cheek -- or was the left cheek? -- (like "face-painting"), or
        C. Watching the "Trashcano" demo -- an erupting volcanco simulation using a liquid nitogen filled soda bottle and a trashcan filled with water and water-balloons -- "erupt" sending water and the balloons over 50 feet high

Trashcano Details: Trashcano | Volcano World | Oregon State University
<--Watch the CVO Open House (May 2, 2015) Trashcano on YouTube (The Columbian)

AN excellent summary of the 1980 Mount St Helens eruption can be found here:
U.S. Geological Survey Fact Sheet 036-00 -- Online Version 1.0
Summary of May 18, 1980 Eruption of Mount St. Helens

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++ QUOTE OF THE DAY ++ -- from the USGS Cascade Volcano Observatory (CVO) reported in its CASCADES VOLCANO OBSERVATORY WEEKLY UPDATE:

CASCADE RANGE VOLCANOES
Current Volcano Alert Level: NORMAL
Current Aviation Color Code: GREEN
Activity Update: All volcanoes in the Cascade Range of Oregon and Washington are at normal background levels of seismicity. These include Mount Baker, Glacier Peak, Mount Rainier, Mount St. Helens, and Mount Adams in Washington State; and Mount Hood, Mount Jefferson, Three Sisters, Newberry, and Crater Lake in Oregon. Additionally, GPS data from most of the major volcanoes, and sparse real-time hydrologic and geochemical monitoring, show no anomalous activity.

[SOURCE: CASCADES VOLCANO OBSERVATORY WEEKLY UPDATE]
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Questions = 2015[20]Q -- Ins-Net Qs for May 15, 2015_"Mount St. Helens: 1980 -- Part 2"
Answers = 2015[20]A -- Ins-Net As for May 15, 2015_"Mount St. Helens: 1980 -- Part 2"

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Please include you name, Callsign, and those correct answers.
Good luck everyone!
Shelley [KF7TBA] & LW [K7LWA]
K7LWA.INS@gmail.com

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KF7TBA+K7LWA's Friday Insomniac-Net BLOG
(http://k7lwa-ins.blogspot.com/)
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