Lahar (dark deposit on the snow) originating in the Mount St. Helen...
Detailed Description
The lahar flowed from the crater into the North Fork Toutle River valley and eventually reached the Cowlitz River 80 km (50 mi) downstream. The lahar also entered Spirit Lake, which can be seen in the lower left corner.
Related
Lahars – The Most Threatening Volcanic Hazard in the Cascades
Lahars, along with debris flows and debris avalanches, are masses of rock, mud and water that travel rapidly downslope and downstream under the action of gravity.
Explosions and Dome Growth
Explosions and Dome Growth, 1980-1986 and 1989-1991.
Related
Lahars – The Most Threatening Volcanic Hazard in the Cascades
Lahars, along with debris flows and debris avalanches, are masses of rock, mud and water that travel rapidly downslope and downstream under the action of gravity.
Explosions and Dome Growth
Explosions and Dome Growth, 1980-1986 and 1989-1991.