Episode Introduction and Context

• Josh introduces SSK Selects episode featuring January 2023 Mount St. Helens eruption episode
• Describes it as packed with "science action adventure heroics life and death danger"
• Hosts: Josh, Chuck, Dave C (sitting in for Jerry)
• Discussion of butter preferences (Kerry Gold mentioned as top-rated)
• Josh was 9 years old during eruption, Chuck was 4

Mount St. Helens Background and Geology

• Stratovolcano created by younger plate subduction under older plate
• Part of Cascade Arc in Pacific Northwest
• Formed over 40,000 years (geologically quick)
• Magma chamber miles below surface
• When no cracks in crust, magma backs up creating pressure
• Previous bulges: Goat Rocks bulge, Sugar Bowl bulge
• Biggest eruption 4,000 years ago (within folktale memory)

Indigenous History and Naming

• Indigenous Cowlitz people called mountain "Lawetlat'la"
• Named after volcanic fire tender woman in legend
• European name from Captain George Vancouver (1792)
• Named after diplomat Allan Fitz Herbert (Baron St. Helens)
• Fitz Herbert never saw the mountain
• Geomyth: legends describe enormous eruption 4,000 years ago
• Tefra layer from ancient eruption: 20 inches thick 62 miles away, extends to British Columbia

19th Century Activity

• Documented eruptions in 1800s
• 1847 eruption painted by Canadian artist Paul Kane
• 1857 was last major eruption before 1980
• 1908: million acres became Columbia National Forest
• 1949: renamed Gifford Pinchot National Forest
• Area included Spirit Lake with youth camps, cabins, recreational activities

Pre-Eruption Warning Signs (1975-1980)

• 1975: two volcanologists published paper predicting 20th century eruption
• March 20, 1980: 4.0 earthquake at mountain kicked off sequence
• Within 5 days: quake storms, 24 quakes of 4.0+ magnitude within 8 hours
• March 25: 24 earthquakes of 4.0+ magnitude in 8 hours
• March 27: first eruption - ash column 6,500 feet high, new crater formed 1,600 feet wide
• March 28: another eruption throwing ash
• Constant warning through mid-May: mudslides, avalanches, growing craters
• Bulge growing 6 feet per day on north side

Key Scientific Personnel

• David Johnston: USGS volcanologist, young and enthusiastic
• Don Swanson: Johnston's partner
• Cold Water 1 station: 8-9 miles from mountain
• Cold Water 2 station: 5-6 miles from mountain (northeast side)
• Johnston and Swanson sounded alarm about evacuation needs

Evacuation Challenges and Politics

• Resistance from local residents (mountain folk)
• Youth groups wanting Spirit Lake access
• Weyerhaeuser logging company pressure (had contracts)
• Surprising pressure to keep mountain open
• Governor of Washington convinced to establish red zone
• May 15th: activity calmed, pressure to reopen
• People signed waivers on car hoods to return
• Perimeter became porous, allowing some through
• 57 total casualties partly due to reopening

Notable Residents

• Harry R. Truman: lodge owner, became folk hero
• Refused evacuation with 16 cats
• Art Carney played him in movie version
• Got extensive media attention
• Determined to "go down with the mountain"

May 18, 1980 Eruption Sequence

• 8:32 AM: eruption triggered by earthquake
• Largest landslide in recorded Earth history
• More than half square mile of mountain vanished
• Dorothy and Keith Stoffel: geologist couple flying 500 feet above
• Dorothy: "whole north half of mountain began churning, mile-long fracture shot across mountain faster than minds could absorb"
• Described as "zipper opening along mountain"

Lateral Blast Characteristics

• Not typical vertical eruption - came out of side
• 24 megaton blast (1,600 times Hiroshima atomic bomb power)
• Moved 6 cubic miles of mountain
• Fast-moving cloud of heat and stones at 300 mph
• Temperature: 660°F (380°C)
• Everything within 8 miles destroyed
• Superheated water flash-heated to steam when pressure released
• 100-foot trees (10-12 feet diameter) completely flattened and debarked

Casualties and Final Transmissions

• David Johnston's final radio transmission: "Vancouver, Vancouver, this is it"
• Only picked up by ham radio operator Jerry Martin
• Martin's final transmission: "gentlemen the camper and car sitting south of me is covered, is going to hit me too"
• Johnston, Martin, and Harry Truman all vaporized instantly
• Johnston Ridge renamed in David Johnston's honor
• Credited with saving thousands of lives through evacuation warnings

Geological Impact

• Landslide carried rocks 558 feet (170m) across - size of 50-story building
• Debris filled valleys, disappeared and reappeared over ridges
• Mountain height reduced by ~600 meters
• North side blown out, creating amphitheater shape
• Natural laboratory for scientists - cross-section of mountain exposed

Environmental Effects

• Spirit Lake: larger but 80 feet shallower, 200 feet higher elevation
• 200 homes/cabins destroyed
• 200 miles of roads and railways obliterated
• All big game animals in blast zone killed
• Smaller animals, plants, microbes, fungi survived underground
• Quick ecosystem rebound from surviving species

Ash and Atmospheric Effects

• Plinian blast followed lateral blast
• Ash plume rose 80,000 feet
• Ash cloud circled globe in 15 days
• Darkened skies, electrical outages
• Close-range ash would burn people alive
• Some crops wiped out, others (wheat, apples) benefited
• Air traffic disrupted - lessons learned for future volcanic events

Water and Flooding Impact

• Snow and glacier ice melted rapidly
• Massive flooding and mudslides
• Lahars (volcanic mudflows) with debris
• Columbia River and Cowlitz River rerouted
• Spirit Lake filled with floating logs
• House filmed floating down engorged muddy river
• High school couple thrown into Spirit Lake, rescued from floating logs

Subsequent Activity

• Multiple eruptions 1980-1996
• Major activity 2004-2008
• Time-lapse footage shows rapid dome growth
• New lava dome growing
• Pressure building - next eruption could be 10 years or 1,000 years
• USGS research station established nearby
• Active ongoing monitoring and study

Legacy and Tourism

• Johnston Ridge renamed after David Johnston
• Memorial and visitor center established
• Trip Advisor reviews praise information center
• Spirit Lake reopened
• Mountain continues to be studied as natural laboratory
• Most documented volcanic eruption in history due to advance warning