Mt St Helens Flashcards
(50 cards)
From _____ 1980 there were signs an eruption could be immanent.
March
Mt St. Helens is a _________ volcano.
Composite
There were small ___________, a bulge appeared on the north side of the mountain called a __________ and ash and _____ were released.
Earthquakes cryptodome steam.
Good management meant that hazardous areas were _________.
Evacuated.
When the earthquakes began in March the ______ _______ __________ ______ started a round the clock monitoring system.
United States geological survey.
It included gathering seismic data measuring the rate of ______ growth ground temperature and sulphur dioxide emissions. ________ and seismic activity reports were issued _____.
Bulge volcanic daily.
USGS scientists issued warnings to the people in the area and gave recommendations about locations of _________ zones.
Hazardous
Based on these recommendations in March access to the volcano was __________ and the evacuation of around ____ people was started.
Restricted 2000
Despite monitoring the volcano, scientists could not accurately predict the eruption. The day of the eruption there were no unusual changes that could be taken as _______ signs.
Warning
A bulge on the _____ side of the volcano indicated that magma was moving up into the magma chamber.
North
__________ were used to monitor the changing size and shape of the mountain which would suggest volcanic activity was about to happen.
Tiltmeters
A tilt meter is an instrument designed to measure very small changes from the __________ level either underground or in structures.
Horizontal
The authorities used ____ eruptions to identify danger zones and evacuated residents from these areas, however some refused to leave and some scientists also ______ to help study the volcano.
Past stayed.
Emergency ___________ and _________ were on hand for when the eruption occurred.
Helicopters and airplanes
The scientists were unable to accurately predict when Mt St Helens would erupt and so people were reluctant to leave their homes for a ____ period of time.
Long
The experts did not predict that the eruption blast would be on the _____ side of the volcano.
North
As a result, the _________ zones were set up in the wrong place and so 90% of the people that died were outside of the exclusion zone in what were thaught to be ____ areas
Exclusion safe
Miami earthquakes began on the __ th _____.
20th March
A bulge appears on the north side of the mountain. This bulge is called a __________.
Cryptodome
___ and ______ were released
ash and steam
On the __ th ___ ____ there was a large earthquakes of magnitude . on the Richter scale followed by a massive eruption of volcanic material including rocks ash hot gasses steam and lava
18th may 1980 5.1
Pyroclastic flows ______ and floods were caused by the volcano.
Lahars - a type of mud flow or debris composed of a slurry of pyroclastic material rocky debris and water.
Floods were caused due to material being dumped in rivers and lakes __________ water.
Displacing
The eruption covered a ____km2 fan shaped area at the north of the volcano , the blast zone. The blast zone reached up to __km away from the volcano.
600 30