Mount St. Helens Eruptive Activity, 1980-1984
Small Explosions
Small explosions sometimes precede or accompany the dome-building
eruptions at Mount St. Helens. If they occur when snow mantles the
crater floor, they can produce mudflows and snow avalanches. The
explosive onset of the March 19, 1982, eruption hurled hot pumice and
dome rocks against the 2,000-feet-high south crater wall, dislodging
snow and rock that avalanched through the crater and down the north
flank of the volcano. Deep snow in the crater melted quickly from the
volcanic heat, forming a temporary small lake from which a destructive
flood swept down the north flank and into the North Fork Toutle River.
About a day later a new lava lobe began to flow down the southeast flank
of the dome.
Continue to Tephra Emissions
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Eruptive Activity
Living Lab Curriculum
Mount St. Helens