These satellite images show the area around Mount St. Helens, in southwestern Washington, before and after its eruption of 18 May 1980.

The cities of Vancouver, Washington and Portland, Oregon are visible in the southwest of the zoomed-out images, north and south of the Columbia River, respectively.

The initial volcanic blast on 18 May 1980 devastated more than 150 square miles of forest within a few minutes. In the following nine hours, volcanic ash rose more than 15 miles into the air, later to land in troublesome amounts as far away as Montana. Sixty people were dead or missing, including one USGS volcanologist, David Johnston, who was monitoring the mountain from nearby.¹

Before the eruption, Mount St. Helens towered about a mile above its base, but on 18 May 1980 its top slid away in an avalanche of rock and other debris. When finally measured on 1 July 1980, the mountain's height had been reduced by 1,313 feet-- from 9,677 feet to 8,364 feet.²

Look at the zoomed-in images. Forested areas appear red. Ash, mudslides, and mud-laden rivers show as grayish blue. Water looks black. Ice and snow are white. Several changes can be seen in these images:

• The north-facing "amphitheater", where the peak of the mountain slid away, is clearest in the 1988 image.

• The North and South Forks of the Toutle River are visible flowing to the west-northwest in the zoom-ins. The avalanche dumped rock and debris into the river valleys, in some places up to 170 m deep.³ Coldwater Creek and Castle Creek, which are tributaries of the Toutle, were blocked by this debris, forming Coldwater Lake and Castle Lake. These are visible in the 1983, 1988 and 1992 images.

• Spirit Lake, northeast of the peak, also flowed into the river. The avalanche raised its level 60 m. Its shape was also affected by debris which entered the lake, and by the floating "raft" of logs which were swept into the lake.

• The 1988 and 1992 images show gradual vegetation regrowth, as light red and pink, in the devastated area.

• Patchwork block patterns, where forest has been cut, are visible especially east of Mount St. Helens. The 1973 zoom-in clearly shows some borders of the Gifford Pinchot National Forest, even without the aid of a map.

1. Bruce L. Foxworthy and Mary Hill, 1982, Volcanic eruptions of 1980 at Mount St. Helens; the first 100 days: U. S. Geological Survey Paper 1249, Washington, D. C. (125 p.), p. 1.

2. Foxworthy and Hill, 1982, p. 11. Lipman, Peter, W., and Mullineaux, Donal, R., (ed.), 1981, The 1980 Eruptions of Mount St. Helens: Washington, U. S. Geological Survey Professional Paper 1250, Washington, D. C. (844 p.), p. 134.

3. Lipman and Mullineaux, 1981, p. 821.

Thanks to Edward W. Wolfe, USGS, for assistance with this article.

Other references

Robert I. Tilling and others, Eruptions of Mount St. Helens: Past, Present, and Future online edition available (as of 28 July 2000) at pubs.usgs.gov/publications/msh.

Decker, Robert, and Decker, Barbara, 1981, The Eruptions of Mount St. Helens: Scientific American, Scientific American, Inc., New York, New York, March, vol. 244, no. 3, p. 68-80.

Findley, Rowe, 1981, Mount St. Helens: Mountain With a Death Wish: National Geographic Magazine, vol. 159, no. 1, January, p. 3-33.

Findley, Rowe, and Raymer, Steve, 1981, Mount St. Helens aftermath, National Geographic Magazine, vol. 160, no. 6, December, p. 713-733.

Hays, W. W., (ed.), 1981, Facing Geologic and Hydrologic Hazards, Earth Science Considerations: U. S. Geological Survey Professional Paper 1240-B, Washington, D. C., 108 p.

Hoblitt, Richard P., 1986, Observations of the eruptions of July 22 and August 7, 1980, at Mount St. Helens, Washington: U. S. Geological Survey Professional Paper 1335, Washington, D. C., 44 p.

Tilling, Robert I., [1984], Eruptions of Mount St. Helens; past, present, and future: Washington, D. C., U. S. Geological Survey, 46 p.

Satellite images

LM1049028007325890 (Landsat 1 MSS, 15 September 1973)

LM4046028008314290 (Landsat 4 MSS, 22 May 1983)

LM5046028008824490 (Landsat 5 MSS, 31 August 1988)

LT5046028009222310 (Landsat 5 TM, 10 August 1992)

LT5046028009623410 (Landsat 5 TM, 21 August 1996)

Special Projects Image

A comparison image of 15 September 1973, 22 May 1983 and 31 August 1988 is available as Special Projects Image E-1851-810CT from EROS Customer Services.

Maps

U.S. Geological Survey, 1945 (compiled 1945, printed 1951), Cascade Range: International Map of the World L-10, scale 1:1,000,000.

U.S. Geological Survey, 1982 (compiled 1961, revised 1982), State of Washington: scale 1:500,000.

Digital Images

USGS-80S-2-010, 10 April 1980, available from EROS Customer Services.

USGS-80S-3-303, 18 May 1980, available from EROS Customer Services.

USGS-80S-5-293, 4 June 1980, available from EROS Customer Services.

The USGS EROS no longer offers hardcopy prints.