Image:Computer animation showing May 18, 1980 St Helens landslide.png
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Description
These illustrations show the landslide (green) and directed blast (red) that occurred during the first few minutes of the eruption of Mount St. Helens in 1980.
Before the eruption, an estimated 0.11 km³ of dacite magma had intruded into the volcano (equivalent to sphere about 600 m in diameter!). The rising magma forced the volcano's north flank (right side of illustration) outward about 150 m and heated the volcano's ground water system, causing many steam-driven explosions (phreatic eruptions).
Following a magnitude five earthquake on the morning of May 18, 1980, a landslide (green) unroofed the hot magma and surrounding hydrothermal system, and the resulting rapid depressurization caused a series of steam and volcanic gas driven explosions. The explosions burst through part of the landslide, blasting rock debris northward. The resulting pyroclastic surge quickly overran the landslide and spread over ridges and valleys across an area of 550 km².
USGS image (by T.R. Alpha) and text from
Summary
| Description |
Computer animation showing May 18 1980 Mount St. Helens landslide |
|---|---|
| Source |
USGS image (by T.R. Alpha) |
| Date |
May 1980 |
| Author |
U.S. government |
| Permission ( Reusing this image) |
PD |
| Other versions | none |
Licensing
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This work is in the public domain in the United States because it is a work of the United States Federal Government under the terms of Title 17, Chapter 1, Section 105 of the US Code. See Copyright. Note: This only applies to works of the Federal Government and not to the work of any individual U.S. state, territory, commonwealth, county, municipality, or any other subdivision. This template also does not apply to postage stamps published by the United States Postal Service. (See 206.02(b) of Compendium II: Copyright Office Practices). العربية | Български | Česky | Deutsch | English | Español | Français | Magyar | Italiano | 日本語 | 한국어 | Polski | Português | 中文(繁體) | 中文(简体) | +/- |
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File history
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| Date/Time | Dimensions | User | Comment | |
|---|---|---|---|---|
| current | 20:36, 13 March 2006 | 788×812 (217 KB) | Reelax | (== Description == These illustrations show the landslide (green) and directed blast (red) that occurred during the first few minutes of the eruption of Mount St. Helens in 1980. Before the eruption, an estimated 0.11 km³ of dacite magma had intruded int) |