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The eruption was preceded by a two-month series of earthquakes and steam-venting episodes, caused by an injection of magma at shallow depth below the volcano that created a huge bulge and a fracture system on Mount St. Helens' north slope. An earthquake at 8:32:17 a.m. on May 18, 1980 caused the entire weakened north face to slide away, suddenly exposing the partly molten, gas- and steam-rich rock in the volcano to lower pressure. The rock responded by exploding a hot mix of lava and pulverized older rock toward Spirit Lake so quickly that it overtook the avalanching north face.
Wiki User
∙ 14y ago
Wiki User
∙ 14y agoMt. St. Helens erupted because the molten lava was producing gases and since there wasn't anywhere for the gas to escape pressure just kept building up until the pressure became to great for the mountain top to hold and it exploded.
Wiki User
∙ 12y agoMt. St. Helens was formed by a series of volcanic eruptions over millions of years.
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Where is Mount Saint Helens found in?
mount baker,mount rainier and mount hood surround mount saint helens
How tall is mount saint helens?
very
How is mount saint helens helpful?
yes it helps you figure out the envirment in washigton dc
What type of landform is mount st helens?
Volcano
Does Mount St Helens lava flow violently or quietly?
Lava can't flow violently. Highly explosive eruptions such as the 1980 eruption of Mount St. Helens do not produce lava flows: they produce clouds of ash, gas, and pumice. Mount St. Helens has produced "quiet" lava flows at times.
How was mount saint helens built?
it was formed not built :) :) :) :)
What plate boundary formed the land features of Mount Saint Helens?
Convergent
Which country is mount saint Helens in?
Mount saint helens is located in the U.S.A.
Is Mount saint Helens in Washington?
Yes. Mount Saint Helens is located in Washington.
Where is Mount Saint Helens found in?
mount baker,mount rainier and mount hood surround mount saint helens
What olate is mount saint helens situated on?
Mount Saint Helens is situated within the Gifford Pinchot National Forest. The olate that Mount Saint Helens is situated is called the subduction zone.
What volcano is close to mount saint Helens?
Mount Saint Helens is the valcano. It's pretty close to itself.
When was mount saint Helens discovered?
Mount Saint Helens was discovered by George Vancouver on May 19, 1772.
Is mount Saint Helens east of Mount Rainier?
No. Mount St. Helens is south-southwest of Mount Ranier.
Is mount St Helens in New Hampshire?
No. Mount Saint Helens is in Washington state.
Which mountain erupted in 1980 in Washington US?
Mount St. Helens is a active volcano, in the Washington State.
What did mount saint helens do?
erupted
