Selects: When Mount St. Helens Blew Its Top
Mount St. Helens, a volcano in the Cascade Arc, erupted catastrophically on May 18, 1980 after months of rising activity and earthquake swarms. The eruption sent an ash plume 80,000 feet high, circling the globe within weeks and disrupting air travel. This episode of Stuff You Should Know explores the historical background of Mount St. Helens, the tragic events leading up to and during its 1980 eruption, and the devastating aftermath.
You'll learn about the warning signs from volcanologists, the massive lateral blast caused by an earthquake-triggered landslide, and the destruction wreaked in the surrounding area—from obliterated homes and infrastructure to the heartbreaking loss of life. The episode also touches on the mountain's continued activity and significance for ongoing volcanic research. Join Josh and Chuck for a dramatic yet sober retelling of this iconic eruption that reshaped the Pacific Northwest landscape.
This is a preview of the Shortform summary of the Jan 25, 2025 episode of the Stuff You Should Know
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1-Page Summary
Historical Context and Background
Mount St. Helens Last Erupted Around 4,000 Years Ago
Mount St. Helens formed relatively quickly over 40,000 years as part of the Cascade Arc, created by tectonic plate subduction. The Puyallup people called it "Luet" after a volcanic fire tender woman, while Europeans named it after Baron St. Helens in 1792. Eruptions continued into the 19th-20th centuries.
The 1980 Eruption
Warning Signs and Evacuations
In 1980, increased activity like quake storms raised concerns. Volcanologists David Johnston and Don Swanson urged evacuations despite local resistance from companies and residents. The governor eventually concurred.
Earthquake Triggers Massive Blast
On May 18, an earthquake caused the largest recorded landslide on Mount St. Helens' north side. This released pressure, causing a 24 megaton lateral blast of superheated steam and debris traveling up to 300 mph and devastation within 8 miles.
80,000-Foot Plume Circled Globe
Mount St. Helens erupted in a massive Plinian eruption, sending an 80,000-foot ash plume that circled the globe in 15 days and disrupted air travel. The eruption cut the mountain's height by 1,300 feet.
Aftermath and Impacts
Destruction and Loss of Life
Over 200 homes, 200 miles of roads/railways, and Spirit Lake were destroyed. The eruption claimed 57 lives, including geologist David Johnston, for whom Johnston Ridge is named.
Continued Activity and Research
Mount St. Helens remains active with new lava domes forming 2004-2008. Research continues on the mountain, providing insights into volcanic processes and ecosystem resilience.
1-Page Summary
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Actionables
- You can create a personal emergency preparedness plan by researching the natural disaster risks in your area and assembling a kit with essentials like food, water, and first aid supplies. For example, if you live near a fault line or a volcano, tailor your kit to include dust masks and eye protection to guard against ash.
- Enhance your travel experiences by visiting geological sites and learning about their history and impact on the environment. When planning your next vacation, choose a destination with a significant geological feature, such as a volcano or canyon, and use local guides to gain a deeper understanding of the area's formation and ecology.
- Foster a greater appreciation for earth sciences by starting a hobby of collecting and cataloging rocks and minerals from different regions. Begin with your local area, looking for unique geological samples, and research their origins and characteristics, which can lead to a broader interest in geology and earth history.
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Historical Context and Background of Mount St. Helens
The historical background of Mount St. Helens reveals a rich tapestry of geological events and indigenous folklore intertwined with European exploration.
Mount St. Helens' Last Major Eruption Was 4,000 Years Ago
The hosts highlight that geologically speaking, Mount St. Helens' formation occurred relatively quickly over about 40,000 years, becoming an active stratovolcano. The major eruption that happened around 4,000 years ago was so powerful that even now, 20 inches of tephra from the eruption can be found 62 miles away from the site.
Cascade Arc Volcanoes Formed by Tectonic Plate Subduction
Mount St. Helens is part of the Cascade Arc, formed when a younger tectonic plate was subducted under an older one. Rock and water heated up from this subduction, causing material to become less dense and rise toward the crust, which led to the formation of many cone-shaped mountains in the Pacific Northwest, including Mount St. Helens.
Indigenous Puyallup Called the Mountain "Luet" for a Volcanic Fire Tender Woman; Europeans Named It After Baron St. Helens in 1792
The indigenous Puyallup people named the mountain "Luet" after a volcanic fire tender woman. According to tribal legends, Mount St. Helens and surrounding mountains stem from a story where the creator God transformed them into mountains due to their quarrel over this woman. ...
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Historical Context and Background of Mount St. Helens
Additional Materials
Actionables
- You can explore the impact of volcanic eruptions on landscapes by creating a layered garden that mimics the strata of volcanic ash deposits. Start with a clear container and layer different colors of sand, soil, and small pebbles to represent the tephra layers from volcanic eruptions. This visual representation can help you grasp the geological processes and the long-term effects of volcanoes like Mount St. Helens on the surrounding environment.
- Enhance your understanding of indigenous cultures and their connections to natural landmarks by researching and creating an art piece inspired by the Puyallup people's stories. Use materials like charcoal or natural pigments to draw or paint the mountain, incorporating elements from the legend of "Luet." This activity connects you to the cultural significance of the mountain and offers a creative way to appreciate the narratives that indigenous peoples have passed down through generations.
- Develop a greater appreciation for historical documentation by trying your han ...
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Events and Details of the 1980 Eruption
The catastrophic 1980 eruption of Mount St. Helens was a significant geological event that provided valuable lessons about volcano monitoring, forecasting, and the sheer power of Earth's natural processes.
Mount St. Helens Showed Signs of Increased Activity Before the 1980 Eruption
In the years leading up to 1980, Mount St. Helens exhibited clear warning signs of an eruption, drawing the attention of volcanologists and the local population. Research conducted by scientists, such as a 1975 paper predicting a likelihood of eruption within the century, pointed to the increasing possibility of volcanic activity. By March 20th, 1980, a 4.0 magnitude earthquake triggered a series of quake storms, fueling concerns about the volcano's impending activity.
Volcanologists including David Johnston and Don Swanson began advocating for evacuations, though they faced local resistance. Companies like Weyerhaeuser with logging contracts and residents such as Harry Truman, who ran a lodge on the mountain, were reluctant to leave. Despite the pressure to reopen the area, the governor of Washington eventually concurred with the scientists to maintain evacuations.
Volcanologists Urge Evacuations Despite Local Resistance
On March 27th, Mount St. Helens erupted, casting a 6,500-foot ash column into the sky and forming a significant crater approximately 1,600 feet wide at the summit. In the lead-up to the May eruption, signs like mudslides and growing craters continued. Around May 15th, some people, enticed by a period of reduced activity, returned to the area, increasing the potential number of victims when the eruption occurred.
Earthquake Triggers Massive Blast, Largest Recorded Landslide on North Side
An earthquake on May 18th resulted in the largest landslide in recorded history on Mount St. Helens' north side, causing over half a square mile of the mountain to disappear. The north flank, which had developed a massive bulge growing six feet per day, collapsed, releasing pent-up pressure and allowing superheated water beneath the mountain to flash into steam and expand rapidly.
Superheated Steam and Debris Devastated the Area At Hundreds of Miles per Hour, Destroying Everything Within 8 Miles of the Mountain
Speakers Josh Clark and Chuck Bryant describe the event as a 24 megaton blast, 1600 times more potent than the Hiroshima atomic bomb, creating a hot, stone-laden cloud traveling at speeds of up to 300 miles per hour and temperatures reaching 660 deg ...
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Events and Details of the 1980 Eruption
Additional Materials
Actionables
- You can enhance your emergency preparedness by creating a personalized evacuation plan based on the Mount St. Helens events. Start by identifying potential natural hazards in your area, such as floods, earthquakes, or volcanic activity. Then, map out escape routes from your home and workplace, designate a meeting point for family members, and prepare an emergency kit with essentials like water, food, a first aid kit, and important documents. Practice your evacuation plan regularly to ensure everyone knows what to do in case of an emergency.
- Develop a habit of staying informed about geological activity by using a smartphone app that alerts you to nearby seismic events. Choose an app that provides real-time alerts for earthquakes, volcanic activity, or other geological changes in your vicinity. By staying informed, you can be more aware of potential risks and take proactive measures to ensure your safety.
- Engage with local community p ...
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The Impacts and Aftermath of the Eruption
The eruption of Mount St. Helens left deep scars on the landscape and communities, with homes destroyed, lives lost, and the environment altered. Research continues to reveal insights into the resiliency of the ecosystem and the volcanic processes at work.
Eruption Destroys 200+ Homes, 200 Miles of Roads/Railways, Spirit Lake Obliterated
The violent 1980 eruption of Mount St. Helens wreaked havoc on the surrounding region. Over 200 homes and cabins, along with approximately 200 miles of road and railways, were obliterated. The eruption brought a cataclysmic change to the terrain, with Spirit Lake greatly altered.
Lake Altered; Larger, Shallower, Outlet Dammed, Flooding Concerns
Spirit Lake, once situated at the base of Mount St. Helens, was transformed into a larger and shallower body of water as its outlet was dammed by debris from the flood. To address flooding concerns and control the depth, a spillway tunnel was constructed five years later.
The Eruption Claimed 57 Lives, Including Geologist David Johnston Monitoring the Mountain
The eruption tragically claimed 57 lives. Among the victims was David Johnston, a geologist with the USGS who was monitoring Mount St. Helens. His efforts to advocate for the evacuation of the area saved thousands of lives. Johnston Ridge was named in his honor, remembering the place where he made his last radio transmission, "Vancouver, Vancouver, this is it."
Additionally, a ham radio operator named Jerry Martin, who was documenting the eruption, transmitted his observation of Johnston's camper being engulfed before experiencing the same fate. His last words, describing the camper covering up and the same fate approaching him, marked the extent of the immediate devastation north of the volcano.
Mount St. Helens Active Post-1980 Eruption; New La ...
Here’s what you’ll find in our full summary
The Impacts and Aftermath of the Eruption
Additional Materials
Actionables
- You can enhance your emergency preparedness by creating a personalized evacuation plan based on the Mount St. Helens event. Consider the natural disasters likely to occur in your area and map out escape routes, meeting points, and have an emergency kit ready. For example, if you live near a flood zone, identify higher ground you can reach quickly and ensure everyone in your household knows the plan.
- Develop a nature journaling habit to appreciate and understand the resilience of ecosystems. Regularly visit a local natural area, observe changes over time, and note them in your journal. This could be as simple as watching how a nearby forest recovers after a storm or how wildlife patterns change with the seasons.
- Volunteer with a local disaster response or environmental conservation ...
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