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CVO Photo Archives
Lahars, Debris Flows, and Mudflows


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Mount St. Helens, Washington

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MSH80_mudline_muddy_river_with_USGS_scientist_10-23-80.jpg
Nearly 135 miles (220 kilometers) of river channels surrounding the volcano were affected by the lahars of May 18, 1980. A mudline left behind on trees shows depths reached by the mud. A scientist (middle right) gives scale. This view is along the Muddy River, southeast of Mount St. Helens.
USGS Photograph taken on October 23, 1980, by Lyn Topinka.
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MSH80_may18_lahar_toutle_river_I-5_bridge_07-06-80.jpg
Toutle River, looking downstream towards the Interstate 5 bridge, from Old Pacific Highway bridge.
USGS Photograph taken July 6, 1980, by Lyn Topinka.
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MSH80_mudline_near_toutle_river_bridge_summer_1980.jpg
U.S. Geological Survey hyrologist (who is 6 feet tall) examines mudline left behind from the May 18, 1980 eruption of Mount St. Helens. Area is near the "Old Highway 99" bridge across the Toutle River, as the Toutle enters the Cowlitz River.
USGS Photograph taken in the summer, 1980, by Lyn Topinka.
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MSH80_devastation_log_camp_south_fork_toutle_05-19-80.jpg
Log camp on the South Fork Toutle River, destroyed from the May 18, 1980 eruption of Mount St. Helens.
USGS Photograph taken on May 19, 1980, by Phil Carpenter.
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MSH81_damaged_home_south_fork_toutle_river_07-19-81.jpg
More than 200 homes and over 185 miles (300 kilometers) of roads were destroyed by the 1980 lahars. Pictured here is a damaged home along the South Fork Toutle River.
USGS Photograph taken on July 19, 1981, by Lyn Topinka.
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MSH80_mailboxes_along_cowlitz_river_1980.jpg
Mailboxes in the mudflow along the Cowlitz River.
USGS Photograph taken in the summer 1980 by Lyn Topinka.
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MSH82_lahar_from_march_82_eruption_03-21-82.jpg
Mount St. Helens erupted often between 1980 and 1986. An explosive eruption on March 19, 1982, sent pumice and ash 9 miles (14 kilometers) into the air, and resulted in a lahar (the dark deposit on the snow) flowing from the crater into the North Fork Toutle River valley. Part of the lahar entered Spirit Lake (lower left corner) but most of the flow went west down the Toutle River, eventually reaching the Cowlitz River, 50 miles (80 kilometers) downstream.
USGS Photograph taken on March 21, 1982, by Tom Casadevall.
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MSH82_bank_erosion_toutle_river_02-22-82.jpg
A major problem to people living downstream of Mount St. Helens was the high sedimentation rates resulting from stream erosion of the volcanic deposits. Streams were continuously down cutting channels, eroding their banks, and eating away at the avalanche and lahar deposits. This material was eventually transported downstream and deposited on the streambeds, decreasing the carrying capacity of the channels and increasing the chances of floods.
USGS Photograph taken on February 22, 1982, by Lyn Topinka.
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MSH81_dredging_toutle_river_02-05-81.jpg
In order to remove the May 18, 1980 sediment deposits, and to keep up with new sedimentation, the U.S. Army Corps of Engineers began a dredging program on the Toutle (shown here), the Cowlitz, and the Columbia Rivers. By 1987, nearly 140 million cubic yards (110 million meters) of material had been removed from the channels. This is enough material to build twelve lanes of highway, one-foot thick, from New York to San Francisco.
USGS Photograph taken on February 5, 1981, by Lyn Topinka.
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Mount Rainier, Washington

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Rainier87_tahoma_creek_debris_flow_deposit_10-01-87.jpg
Debris flow deposit, Tahoma Creek, Mount Rainier, Washington.
USGS Photograph taken on October 1, 1987, by Lyn Topinka.
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Pinatubo, Colombia

Image, Armero Colombia after November 1985 Nevado del Ruiz Lahar, click to enlarge
Ruiz85_aerial_lahar_armero_12-09-85.jpg
Armero, Colombia, destroyed by lahar on November 13, 1985.More than 23,000 people were killed in Armero when lahars (volcanic debris flows) swept down from the erupting Nevado del Ruiz volcano. When the volcano became restless in 1984, no team of volcanologists existed that could rush to the scene of such an emergency. However, less than a year later, the U.S. Geological Survey organized a team and a portable volcano observatory that could be quickly dispatched to an awakening volcano anywhere in the world.
-- USGS Photo by R.J. Janda, December 9, 1985
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06/24/09, Lyn Topinka