Dangers in the Backyard The Effects of Mount St. Helens and the Similar Dangers Near Mount Rainier Maritza Fuljencio Geology 108 Professor Anderson

The Cascade Range Mount Rainier and Mt. St. Helens are part of the chain of volcanoes in the Cascade Range Volcanoes are part of the ring of fire, which is caused by collisions with the Juan de Fuca plate and the North American plate

List of Cascade Range Volcanoes

Cascade Volcanoes with the Juan de Fuca Plate and the North American Plate

Various Cascade Range Volcanoes Mount Hood (OR)Mount Adams (WA) Mount Jefferson (OR)Lassen Peak (CA)

Eruption of Mount St. Helens In 1974, geologists Dwight Crandell and Donal Mullineaux published a paper where they determined that Mt. St. Helens would erupt by the end of the century. Volcano activity started in March 1980 after 123 years in hibernation, with small earthquakes and phreatic eruptions.

In late April 1980, a bulge on the north side of the volcano started to grow out on an average of 5-6 inches a day. The volcano erupted at 8:32AM on May 18, A 5.1 earthquake caused the north slope to fall in a landslide.

Moments after the slide of the bulge, the high- pressured steam that was under the bulge gave way as a debris avalanche and created a combination of lateral blasts and pyroclastic flows. An additional plinean eruption about 10 minutes after the first eruption caused a vertical column of ash. This ash traveled through the air in the northeastern direction, reaching the cities of Yakima and Spokane, Washington. The ash continued to travel to Idaho, Montana, and Wyoming.

Mt. St. Helens Eruption Sequence

Devastation to Mount St. Helens Area

Ash Distribution Within the United States From Mt. St. Helens

- Mount St. Helens eruption was the most deadly volcanic event in the United States - Human life fatalities were 57 - Much damage to the environment nearby (trees were knocked down and destroyed by the lateral blasts) - Agricultural crops and wildlife, such as deer and salmon, were damaged and killed

- Mount St. Helens released an amount of energy equivalent to 27,000 Hiroshima-sized atomic bombs (approximately 350 megatons) and ejected more than 1 cubic mile (4 km³) of material. - Removal of the north side of the mountain reduced St. Helens' height by about 1,313 feet. - Cost of the eruption was $1 billion dollars.

Mount Rainier Stratovolcano located 54 miles southeast of Seattle Highest peak in Cascade Range at 14,411 feet Covered by snow and glaciers Geothermal heat has caused the formation of ice caves in summit craters

Dangers of Mount Rainier Rainier is only 35 miles from the Seattle-Tacoma metropolitan area of 2.5 million people The history that exists of Mount Rainier and its eruptions shows a direct risk and danger to those living close to the mountain

Historical Evidence 5,700 years ago, there were a series of lahar flows known as the Osceola Mudflows. These originated from both the summit and northeast flank. The cause for the lahar was a collapse of part of the mountain and an avalanche that followed.

This flow made its way down the White, Green, and Puyallup Rivers and finally into Puget Sound, present-day Tacoma and south Seattle. The dangers remain in that the present-day towns of Buckley, Enumclaw, Pacific, Auburn, and Sumner were built on the deposits from the Osceola Mudflows.

Modern-day Dangers to Cities near Mt. Rainier

- Should a lahar flow now travel at the same speed that the Osceola Mudflow traveled, it would only give up to three hours for evacuation time. - USGS has developed a lahar warning system for neighboring towns in the Puyallup River valley.

The United Nations, in 1990, designated Mount Rainier as a “Decade Volcano” Requirements for volcanoes being named to this list: - “volcanoes represent[ing] a variety of eruptive styles and potential hazards” - “generally being located in accessible, populated regions and are geologically active but not well studied.”

Reasons the United Nations gave for Mount Rainier: - “It has an extensive but poorly studied geological and historical record of activity, including lava flows, ash eruptions, avalanches, and mudflows.” - In addition, they noted, “it poses an additional hazard because of its extensive cover of snow and ice, which, if melted rapidly, could produce catastrophic floods and mudflows.”

Case in Point The devastation of Mt. St. Helens could have been greater if it were not for early evacuations There is no guarantee of early evacuations if Mt. Rainier were to suddenly erupt The extensive history of Mt. Rainier shows the extent of damage a lahar flow can cause in the future

There has not been sufficient research and analysis on Mt. Rainier’s history to help prepare for a disaster The lahar warning system for the Puyallup River Valley is a step in the right direction The next step should be to address the evacuation concerns of the Seattle-Tacoma metropolitan area

Washington needs to be prepared for Mount Rainier to be the “next big one” before it is too late…

Sources Slide 2: Fisher, Richard V., Grant Heiken, and Jeffrey B. Hulen. Volcanoes: Crubiles of Change. Princeton: Princeton University Press, p Slide 4: Scarth, Alwyn. Volcanoes: An Introduction. Somerset: Texas A&M University Press, p 89. Slide 6: Zeilinga de Boer, Jelle and Donald Theodore Sanders. Volcanoes in Human History. Princeton: Princeton University Press, p Slide 7: Scarth, Alwyn. Volcanoes: An Introduction. Somerset: Texas A&M University Press, p 90. Slide 8: Scarth, Alwyn. Volcanoes: An Introduction. Somerset: Texas A&M University Press, p 34. Fisher, Richard V., Grant Heiken, and Jeffrey B. Hulen. Volcanoes: Crubiles of Change. Princeton: Princeton University Press, p 16. Zeilinga de Boer, Jelle and Donald Theodore Sanders. Volcanoes in Human History. Princeton: Princeton University Press, p 237. Slide 11 and 12: Scarth, Alwyn. Volcanoes: An Introduction. Somerset: Texas A&M University Press, p 93.

Slides 14 and 15: Kirk, Ruth. Sunrise to Paradise: The Story of Mount Rainier National Park. Seattle: University of Washington Press, p 9. Slides 16 and 17: Fisher, Richard V., Grant Heiken, and Jeffrey B. Hulen. Volcanoes: Crubiles of Change. Princeton: Princeton University Press, p 129. Slides 19, 20, and 21: National Research Council Staff. Mount Rainier : Active Cascade Volcano. Washington, DC, USA: National Academy Press, p Pictures in slides 3, 5, 7, 9, 10, 11, 18, and 19: copyright United States Geological Service: Picture in slide 4: Scarth, Alwyn. Volcanoes: An Introduction. Somerset: Texas A&M University Press, p 89.