This lateral blast toppled or snapped off trees over a 230-square-mile area north of the volcano, which later became known as the blowdown zone. A hot stone-filled wind surged north at speeds over 300 miles per hour and temperatures of 660 ☏. The hot water burst into steam and blasted out the new opening in a powerful lateral blast. With the north side of the mountain gone, pressure was released on hot water within the volcano. The third and largest lobe traveled 14 miles down the Toutle River valley, filling the valley to an average depth of 150 feet and leaving mounds of sediment in a bumpy pattern of hummocks.Ī lateral blast ejected 660 ☏ steam and stones at more than 300 miles per hour The second lobe of the debris avalanche surged over a 1,300-foot ridge and spilled into the South Coldwater Creek drainage. As the water flowed back downhill, it dragged thousands of trees into the lake where the trees covered much of the surface. One lobe of the debris avalanche smashed into Spirit Lake, pushed the lake water up the surrounding slopes, and raised the lakebed 200 feet. Scientists set up permanent plots in 1980 to observe how life responded after the blast (photo by Charlie Crisafulli).The entire northern side of the volcano collapsed in a massive debris avalanche. Helens’ north side collapsed in a debris avalanche These volcanic events buried some areas in debris avalanches and mudflows, scoured other areas with hot gases, blew down or scorched forests on slopes several miles away, and dusted forests farther away with volcanic ash. The eruption involved a complex series of events that unfolded over the next 12 hours, with many events going on simultaneously. Helens and triggered an enormous eruption. On the morning of May 18, 1980, after weeks of small tremors, a magnitude 5.1 earthquake shook beneath Mount St. How were reptiles affected by the eruption?įAQ 1: What happened during the big eruption of 1980?

How were amphibians affected by the eruption? How were large mammals affected by the eruption? How were small and midsize mammals affected by the eruption? How were birds initially affected by the eruption? What was the landscape like after the eruption? What happened during the big eruption of 1980? If you have specific questions not addressed by this list, please contact us for more information. You can control the level of detail you receive in response to each question by expanding or collapsing the content using the and buttons. Learn more about the 1980 eruption and its ecological responses by browsing the frequently asked questions below. Pacific Northwest Research Station scientists were among the first to arrive on the scene after the eruption, ready to assess the effects of the disturbance and to develop a research strategy to study the landscape’s ecological responses.

Ne yo one in a million chipmunk