Paper 1- Tectonic hazards Flashcards
where are volcanos found?
Wherever magma rises to the surface: conservative margins, subduction zones and hot spots
What three substances do volcanos emit
Lava, pyroclastic material, Gases
While magma is molten rock beneath the surface, lava is…
magma running over the surfcae
Acid lava characteristics
High silica content
temp around 700 degrees
very viscous, sticky
forms rhyolite or andesite rock
associated with destructive plate margins
Basic lava characteristics
Low silica content
Temp around 1200 degrees
non-viscous, runny
forms basalt rock
associated with tensional margins and hot spots
why are acid eruptions more dangerous?
Pockets of gas - when exploding its sticky
Example of a shield volcano
Mauna Hoa in Hawaii
Example of a composite cone (strato volcano
Mt Fuji
Mt Rainier
Lava flow primary impact
Eruption of Eldfell, at Haimaey, Iceland 1973
lava destroyed over 300 buildings.
But town and fishing port were saved by spraying water
Pyroclastic flow primary impact
E.g. Eruptionn of mt. Pelée, Martinique in 1902
A hot ash cloud wiped out St Pierre, over 25,000 deaths
Ash and ash fal primary impact
E.g. Eyjafallajokull, Iceland 2010
Glacier ice on top of the erupting volcano cause a huge ash cloud that caused over 100,000 flight cancelations and around 1bn dollars
Volcanic gases primary impact
E.g. Lake Nyos volcano, Cameroon in 1986
A large cloud of CO2 was released from the lake within the crater, this travelled downhill 15 miles, killing 1700 people
Volcanic mudflows (lahars) secondary impact
Eruption of Nevado del Ruiz, Colombia in 19985
Volcanic ash and rocks mixed with snow and ice on mountaintop to produce lahar
Swept across the town of Armero killing 23,000 people
Tsunamis secondary impact
E.g. Eruption of Krakatau, Indonesia in 1883
caused the collapse of the island producing large tsunamis that killed 36,000 people
VEI - Volcanic Explosive index
from 0 to 8
Each step up from 2 is a 10x increase in the volume of solid material produced by the eruption
E.g. 1km^3 Mt St Helens
Super volcano 10,000km^3