Transcript mount st helens presentation byme nd rachael welton

BY RHIANNON AND RACHAEL
• An eruption of hot volcanic ash rose 80,000
feet (24,400m) into the sky.
• At the same time, ice, snow and several
glaciers which were on the volcano melted
forming a large series of lahars that reached as
far as the Columbia River ( nearly 50 miles to
the south west)
It was the biggest landslide in history.
Landslide went east and west.
Before
•Mount st Helens is skamania country, washington,
U.s.
•It is in the cascade range.
•The rock about is 40,000 years old.
Before
After
After
Mount st Helens erupted on may the 18th
1980.
Mount St Helens has an elevation of
2549m (8364ft)
Warning
signs
• From January 1975 through
early 1980 only 44
earthquakes were located
within 35km (22mi) of the
volcano.
• A "bulge" developed on the
north side of Mount St.
Helens as magma pushed
up within the peak.
• People were evacuated
from a 5 mile radius.
What was the impact?
57 deaths
$1.1billion in property damage
Ash fell in 11 states
The large lahars reached nearly 50 miles (80km)
to the southwest.
200 houses destroyed
27 bridges destroyed
The phyroclastic flow was nearly 300mph-20
miles
230 square miles of forest was destroyed
• It was about 24 hours after the eruption
before any help could happen.
• Spirit lake got dammed by debris which meant
that it would start to flood. To prevent this
from happening people pumped the water out
until they were able to drain some of the
water through pipes.