Mount St. Helens changed the way we look at things!

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Martin Welch
6 years ago
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volcanoes Helens changed the way we look at things!

Centralia College View to the north-northwest after noon; photo by Bob Krimmel,

use of selected images USGS Photo by Claude Palmer, 1937, courtesy of Photo Art

Native American legends and geologic evidence can tell us about prehistoric

Pahto (Mount Adams) and Wy-east (Mount Hood) fought over a young maiden,

1847 Don Lawrence, tree-ring pioneer in the NW SET C first effort to date

1 Mount St. Helens, a turning point in studies of, and perceptions about explosive volcanoes Mount St. Helens changed the way we look at things! Plinian column during the cataclysmic eruption of May 18, 1980 Pat Pringle Centralia College View to the north-northwest after noon; photo by Bob Krimmel, I m grateful to Keith Ronholm, Cathie Hickson, Fred Swanson, and Lisa Faust for use of selected images USGS Photo by Claude Palmer, 1937, courtesy of Photo Art Studios. Looks SSW across Spirit Lake. Native American legends and geologic evidence can tell us about prehistoric eruptions. Pahto (Mount Adams) and Wy-east (Mount Hood) fought over a young maiden, Loo-wit Lat-kla An eruption from the Goat Rocks dome as painted by Paul Kane in 1847 Don Lawrence, tree-ring pioneer in the NW SET C first effort to date postglacial eruptive products of Mount St. Helens MSH SET P MSH SET Y B F D Mazama Lawrence & Lawrence, 1959 Photo by Don Mullineaux; Tephra in Ohanapecosh Park at MountRainier the evidence for Mount St. Helens explosive past is first recognized in MSH pumice found at Mount Rainier by Don Mullineaux

Helens 1980 Crater Ape Canyon 300 250 ka

2 Clynne, M, 2005 USGS Fact Sheet the Yn tephra changed settlement patterns in the SW Washington Cascade Range for more than 1700 years! Rick McClure, USFS Volcano Hazard Map we we ve learned a great deal from the modern eruptions of Mount St. Helens Goat Mtn.~220 ka Pine Creek deposits, ~3 2.5 ka 2.8 ka breaching of debris-dammed lakes ~20 ka lava flow oldest exposed rock on MSH USGS geologist Kevin Scott exams deposits of humongous ancient lahars 50 km downstream of Mount St. Helens Mount St. Helens 1980 Crater Ape Canyon ka ka Cougar ka Swift Creek ka Spirit Lake ka Clynne, 2005; Clynne et al., 2008; Mullineaux and Crandell, ~2.8 ka debris avalanche deposits that blocked the lakes!! Eruptive History

Small phreatic eruption on May 11, 1980; view to south; dashed area

Helens, March 30, 1980, Mount Adams to right (east) Mount St.

could transpose to other stratovolcanoes Mount St.

Photo by Gary Rosenquist from Bear Meadow, ~11 km northeast of the

3 Small phreatic eruption on May 11, 1980; view to south; dashed area is deforming. WA Div. of Geology photo of Mount St. Helens, March 30, 1980, Mount Adams to right (east) Mount St. Helens allowed a visualization of volcanic processes that people could transpose to other stratovolcanoes Mount St. Helens May 18, 1980, seconds after the beginning of the eruption. Photo by Gary Rosenquist from Bear Meadow, ~11 km northeast of the volcano. Photo by Keith Ronnholm; ~13 sec after eruption start Photo by Keith Ronnholm; ~31 sec after eruption start

4 copyrighted photo by Keith Ronnholm Eye-witness photos by Paul and Cathie Hickson Photos by Paul and Cathie Hickson from the east, 5/18/80 Photo by Keith Ronnholm copyrighted photo by Gary Rosenquist

5 Mount St. Helens Plinian column during the cataclysmic eruption of May 18, 1980 View to the north-northwest after noon; photo by Bob Krimmel, USGS Photo by Paul and Cathie Hickson Lahar Effects Erosion Burial Impact Altered channels Montserrat Volcano Observatory Blowdown Blast Zone Hummocky 1980 debris-avalanche deposit of Mount St. Helens as seen from the Hummocks Trail, about 9 km from the volcano.

6 Mudflow Pyroclastic flow of August 7, 1980 at Mount St. Helens Pumiceous pyroclastic flow deposit; >700 deg C early dome formation, summer 1980 Some domes survived! December

7 Lahar Hazards Origin Eruption-induced induced melting of ice and snow Debris avalanche Lake breakout Erosion of tephra and other sediments March 19, 1982 lahar March 29, 1984, ~4 AM May 14, 1984 explosion and lahar! Ken Cameron photos photo by Jack Hash October 26, 1986, final extrusion of lava for the dome A glacier s birth, 1990s

Daryll Lloyd photo of east terminus of the

as measured July 5, 2007, was 122 million cubic

sports stadiums) and was growing at an average

14 cubic yards per second (nearly equivalent to

8 Daryll Lloyd photo of east terminus of the Crater Glacier The volume of the new lava dome as measured July 5, 2007, was 122 million cubic yards (volume is equivalent to 150 to 200 large sports stadiums) and was growing at an average rate of 0.14 cubic yards per second (nearly equivalent to filling 4 Olympic-sized swimming pools every day. [Information release, February 21, 2008]

9 Mount St. Helens Erosion reveals longburied deposits & buried trees: amazing opportunities to study the past Societal Unrest Wn late AD 1479 We ~AD 1482 X ~AD T Agency control Sediment control Fish and game Public access ~AD 1800 Floating Island Lava ~AD1800 Goat Rx dome ~AD Dave Yamaguchi, 1980s(many papers) *Kalama Eruptive Period AD 1480 to mid 1700s *Goat Rocks Eruptive Pd. AD 1800 to ~1859 Advancing Earth Sciences -Poorly known processes Orting Electron Mudflow ~A.D New Tools, New Deployments, Sensor Arrays Nevada del Ruiz Service to Society -USGS Volcano Disaster Assistance Program

10 Mount St. Helens, a natural learning and research laboratory

Debris Avalanches. Debris avalanche deposits on a volcano in Chile. All of the area in the foreground is buried by a thick debris avalanche.

Debris Avalanches. Debris avalanche deposits on a volcano in Chile. All of the area in the foreground is buried by a thick debris avalanche. Debris Avalanches Volcanoes are not very stable structures. From time to time, they collapse producing large rock and ash avalanches that travel at high speeds down valleys. Collapse maybe caused by an