Geology Reference
In-Depth Information
3. Mount St. Helens' lateral blast on May 18, 1980, took
place when a bulge on the volcano's north face collapsed,
reducing the pressure on gas-charged magma.
4. Mount St.
Helens' lateral
blast killed about
63 people and
leveled 600 km
2
of forest. These
trees in Smith
Creek Valley are in
part of the blast
zone. For scale,
see the two men
within the red circle.
5. Shortly after the lateral blast on May 18, 1980,
this 19-km-high ash and steam cloud erupted
from Mount St. Helens.
7. A huge steam explosion called the
Great Hot Blast leveled the area in
the foreground in 1915. In the 88
years since the eruption, trees are
becoming reestablished in this area,
known as the Devastated Area.
6. Lassen Peak erupted numerous
times from 1914 to 1917. This
eruption took place in 1915.
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