Mount St. Helens lost its symmetrical summit on May 18, 1980: the north flank collapsed and the eruption blasted out a horseshoe-shaped crater open toward the north. Toggle the ghost outline of the pre-1980 summit and the lava dome that has been rebuilding inside the crater ever since.
Published figures: current elevation about 2,549 m; pre-1980 summit about 2,950 m - roughly 400 m of the peak was lost; the crater is horseshoe-shaped, about 2 km wide and 3.5 km long, open to the north; a lava dome has been rebuilding inside the crater since 1980.
Drag to orbit and scroll or pinch to zoom. Everything renders on your device with WebGL.
Mount St. Helens 3D Explorer
This browser explorer shows Mount St. Helens in cross-section: the horseshoe-shaped crater blasted open toward the north on May 18, 1980, and the lava dome that has been rebuilding inside it ever since. A ghost outline marks where the original, taller summit used to stand before the eruption tore it away.
Mount St. Helens is an active stratovolcano in the Cascade Range of Washington State, part of the Pacific Ring of Fire. The 1980 eruption is one of the most studied volcanic events in US history: a massive debris avalanche, commonly cited as the largest landslide ever recorded, stripped the north flank away in seconds, and the resulting lateral blast flattened forest for kilometers around. Inside the horseshoe crater left behind, a lava dome has grown episodically ever since, adding fresh rock with each new eruptive phase.
- Toggle the pre-1980 summit outline to compare today's truncated peak with the original cone
- Toggle the lava dome to see the rock pile rebuilding inside the crater
- Read elevation, crater size, and eruption figures in the panel
- Drag to orbit, scroll or pinch to zoom
- Runs fully in the browser with the vendored three.js engine - no account, no upload
| Figure | Published value |
|---|---|
| Current elevation | about 2,549 m (8,363 ft) |
| Pre-1980 summit elevation | about 2,950 m (9,677 ft) - roughly 400 m was lost in the eruption |
| May 18, 1980 eruption | a massive debris avalanche and lateral blast; one of the deadliest and most destructive volcanic events in US history |
| Crater | horseshoe-shaped, open to the north, roughly 2 km wide and 3.5 km long |
| Lava dome | has grown episodically inside the crater since 1980, most recently in 2004-2008 |
| Location | Cascade Range, Skamania County, Washington, USA - part of the Pacific Ring of Fire |
For other volcanoes on this site, open the Krakatoa 3D Explorer to see a collapsed caldera regrowing from the sea, or the Kilauea 3D Explorer for an active shield volcano's lava lake.
The whole Mount St. Helens scene - the horseshoe crater, the ghost outline of the lost summit, and the rebuilding lava dome - is built and drawn on your own device with WebGL through the site-vendored three.js engine. Orbit the scene to look into the breached crater from different angles, and toggle the pre-1980 outline to see how much of the mountain the eruption removed. Nothing about your visit is uploaded to a server, and the engine loads once (about 0.7 MB) and is then cached.
This is an educational approximation - the crater shape, dome, and pre-1980 outline are schematic teaching cues, not survey data.
Frequently Asked Questions
Why is Mount St. Helens crater shaped like a horseshoe?
The May 18, 1980 eruption began with a massive debris avalanche that stripped away the north flank, then a lateral blast tore the crater open toward the north - leaving a horseshoe-shaped amphitheater instead of a closed ring.
How much of the mountain did the 1980 eruption remove?
About 400 m of elevation - the pre-1980 summit stood about 2,950 m; today's summit is about 2,549 m.
What is the lava dome inside the crater?
A mound of hardened lava that has rebuilt episodically inside the crater since 1980, most recently during a 2004-2008 eruptive phase, partially refilling the space the 1980 blast opened up.
Is Mount St. Helens still active?
Yes - it is an active stratovolcano in the Cascade Range, part of the Pacific Ring of Fire, and is intensively monitored for renewed activity.
Where is Mount St. Helens?
In the Cascade Range in Skamania County, Washington State, USA.
Is this a scientific terrain model?
No. It is an educational explorer using published figures - the crater shape, lava dome, and pre-1980 outline are schematic teaching cues, not survey data.