what is mount st helens?
Stratovolcano Volcano
contradiction
 Mount St. Helens or Louwala @-@ Clough ( known as Lawetlat 'la to the indigenous Cowlitz people , and Loowit to the Klickitat ) is an active stratovolcano located in Skamania County , Washington , in the Pacific Northwest region of the United States . It is 96 miles ( 154 km ) south of Seattle , Washington , and 50 miles ( 80 km ) northeast of Portland , Oregon . Mount St. Helens takes its English name from the British diplomat Lord St Helens , a friend of explorer George Vancouver who made a survey of the area in the late 18th century . The volcano is located in the Cascade Range and is part of the Cascade Volcanic Arc , a segment of the Pacific Ring of Fire that includes over 160 active volcanoes . This volcano is well known for its ash explosions and pyroclastic flows . 

contradiction
 Mount St. Helens , which exhibited phreatic activity just prior to its catastrophic 1980 eruption ( which was itself Plinian ) . 

contradiction
 The 1980 eruption of Mount St. Helens in Washington , which ripped apart the volcano 's summit , was a Plinian eruption of Volcanic Explosivity Index ( VEI ) 5 . 

contradiction
 As with most other volcanoes in the Cascade Range , Mount St. Helens is a large eruptive cone consisting of lava rock interlayered with ash , pumice , and other deposits . The mountain includes layers of basalt and andesite through which several domes of dacite lava have erupted . The largest of the dacite domes formed the previous summit , and off its northern flank sat the smaller Goat Rocks dome . Both were destroyed in the 1980 eruption . 

contradiction
 The active Mount St. Helens was radically different from its dormant form , now featuring an enormous bulge and several craters . In the week preceding the eruption , cracks formed in the north sector of the volcano 's summit , indicating a movement of magma from the bulge and towards the caldera . 
