PDX Index: Mount St. Helens

30th Anniversary

By Taryn Wheeler April 20, 2010 Published in the May 2010 issue of Portland Monthly

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Number of years the mountain lay dormant before its May 1980 eruption


Magnitude of earthquake that caused the largest landslide in recorded history, which triggered the 1980 eruption


Number of minutes it took the blast to flatten 230 square miles of forest

4 billion

Board feet of timber damaged or destroyed by the eruption (enough to build about 500,000 two-bedroom homes)

125 million

Amount, in cubic yards, of lava that erupted from October 2004 to January 2008 (enough to pave a three-foot-thick, seven-lane highway from Portland to New York City)


Number of lakes, ponds, and wetlands carved out by the eruption’s landslide


Amount, in millions, that Congress allotted for disaster relief after the eruption


Acres of land protected by the Mount St. Helens National Volcanic Monument, established by Congress in 1982


Projected number of years before the blast zone will begin to resemble pre-eruption, old-growth forest


Number of distinct eruptive periods over the past 4,000 years (Mount St. Helens is the most active volcano in the Cascade Range)

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