volcanos

Question 1

explain the distribution of volcanos

Answer 1

there is clear correlation between volcanos and plate boundaries. however, there are anomolies to this pattern, these are known as hot spots

Question 2

what are the three volcano status’

Answer 2

active, dormant, extinct

Question 3

what is meant by the term active volcano

Answer 3

at least one eruption during the past 10,000 years. an active volcano might be erupting or dormant

Question 4

what is meant by dormant volcanos

Answer 4

at least one eruption during the past 10,000 years, but there is no current activity

Question 5

what is an extinct volcano

Answer 5

a volcano that has not erupted in the past 10,000 years. an eruption will not happen again

Question 6

why is 10,000 years a significant amount of time in determining the status of a volcano

Answer 6

time since the last ice age

Question 7

give an example of each volcano status

Answer 7

active= Mauna Loa, Hawaii
Dormant= Mount Vesuvius, Italy
Extinct= castle rock, edinburgh

Question 8

what is tepography

Answer 8

the relief/ shape of a volcano

Question 9

what are the two types of volcano

Answer 9

shield volcanos

composite volcanos

Question 10

what is the main difference between shield and composite volcanos

Answer 10

shield volcanos= effusive eruptions

composite volcanos= explosive eruptions

Question 11

what is viscosity

Answer 11

the thickness of lava

Question 12

what are three key factors to consider when determining how a volcano will erupt

Answer 12

temperature of lava, silica content in lava, volume of dissolved gas

Question 13

how will the temperature of lava have impact

Answer 13

the higher the temperature, the more runny the magma. runny lava wont block the main vent resulting in effusive eruptions

Question 14

how will silica content impact an explosion

Answer 14

the higher the silica content, the thicker the magma (silica absorbs water). Thick lava will block up the main vent, trapping gas and increasing pressure resulting in explosive eruptions.

Question 15

how will volume of dissolved gas impact an eruption

Answer 15

the higher the dissolved gas, the more runny and buoyant the magma will be. The higher the temp= more gas dissolved in magma = more runny magma will be = vent is not blocked so gases can escape easily so no pressure built up leading to less explosive eruptions

Question 16

what are the three types of magma

Answer 16

basaltic, rhyolitic, andesitic

Question 17

what is the most explosive type of magma and most effusive type of magma

Answer 17

most explosive = rhyolitic

least explosive= basaltic

Question 18

describe basaltic magma

Answer 18

low viscosity (runny), easy release of gas, non violent eruptions, runny lava will create low cones. formed by the melting of ocean crust and mantle so occur at divergent boundaries and hotspots.

Question 19

describe andesitic magma.

Answer 19

high eruption columns spread gas over large distances as it pernitrates the troposphere. eruption columns may collapse which will result in pyroclastic flow. andesitic is intermediate lava which is formed by rising basaltic lava mixing with continental crust before it reacts with the surface resulting in a violent eruption. This lava is largely formed at the subduction zone.

Question 20

describe rhyolitic lava

Answer 20

thick ,viscous magma cools in the main vent, plugging it and causing a build up of pressure which results in sudden , violent eruptions, rhyolitic lavas with high silica content are formed from the melting of continental crust so form at convergent boundaries.

Question 21

what is the troposphere

Answer 21

lowest and first layer of earths atmosphere.