volcanoes and earthquakes

Question 1

structure of the earth

Answer 1

crust
mantel
outer-core
inner-core

Question 2

crust

Answer 2

outer layer, can be thick or thin depending if its on land or ocean
oceanic crust (heavy basaltic rocks)
continental crust (granite rocks, lighter and stronger)

Question 3

mantel

Answer 3

just below the curst, its a bit like a semi-solid layer.
hot currents moving it causing plates to shift

Question 4

outer-core

Answer 4

beneath the mantle, its a liquid layer made of melted iron and nickel. this creates the magnetic field around the earth

Question 5

inner-core

Answer 5

at the very center, there’s a solid ball of iron and nickel. this solid part also adds to the earth’s structure and its magnetic effects.

Question 6

plate techtonics

Answer 6

earths outer layer
like a puzzel piece: lithospheric plates
these plates float of gooey layer: as asthenosphere
below there’s a slower river of hot melted rock: magma moving steadily
seven major tectonic plates
made up of different types of crust

Question 7

plate boundries

Answer 7

where plates rub, crash, move away from eachother

Question 8

types of volcanoes

Answer 8

-active- still erupting frequently
-dormant- not currently errupting but could
-extinct- highly unlikely to errupt
-shield volcanoes- low, gently-sloping sides, formed from thin runny lava and have fairly frequent gently eruptions
- strato volcanoes- alternating layers of ash and lava, eruptions can be violent with ash clouds and lava flows and flows down very fast at high degrees.

Question 9

effusive eruputions

Answer 9

flows li,e snow, smooth syrap. lava is runny and thin

Question 10

explosive eruptions

Answer 10

explodes like a burst of fireworks, lava is think and gooey and explodes violently. rocks, ash, debris is thrown into the air =. pyroclastic flows mixing with hot steam ash, rock and dust. these move down the volcano very fast up to 400c

Question 11

zones of activity

Answer 11

where plates are in almost constant motion. are the plate boundires or margins. these margins are classified in 4 types of groups.

Question 12

constructive margins

Answer 12

when 2 plates move away from each other
magma rises from the mantel filling the gap, creating new oceanic crust. called sea-floor spreading
mid- atlantic ridge

Question 13

destructive margins

Answer 13

where continental crust and oceanic crust moves to each other and subduction occurs. (bc oceanic is heavier)
friction causes the crust to melt and some newly formed magma may be forced to surface, forming volcanoes.
can trigger earthquakes, forms trenches

Question 14

conservative margins

Answer 14

where two plates slide past each other
no new activity, earthquakes can occur
pressure will build until released causing earth to jerk violently

Question 15

converge

Answer 15

—-> <—- (destructive, subduction)
volcanoes, earthquakes, trenches

Question 16

diverge

Answer 16

<—- —-> (constructive) (subduction)
volcanoes, earthquakes

Question 17

conserve

Answer 17

<—- (conservative)
—->. no transformation (if stuck = earthquake)

Question 18

collision

Answer 18

—-> <—- (2 continental plates)
earthquakes

Question 19

seismic activities

Answer 19

movement of the earth in an earthquake
measured in a seismograph (seisometer)
measures how much the earth shakes and plots this on a graph

Question 20

how is the magnitude of an earthquake measured?

Answer 20

strength (magnitude) of an earthquake is measured using the richter scale
an increase 1 = x10 = shaking x10 more = more severe

Question 21

why live next to a volcano eventhough it is dangerous

Answer 21

fertile land- the ash forms an excellent soil for growing crops and providing food
farming near volcanoes has been going on a long time and now the small settlements have changed into important regional centuries
many volcanoes have become tourist attractions and local businesses have sprung up around them providing much needed employment
many volcanoes are in poor countries so the people don’t have the money to move.

Question 22

case study- volcano in Montserrat

Answer 22

before 1995, most 11,000 people relied on tourism and farming on the fertile land
Montserrat sits on the destructive (subduction) between Caribbean and atlantic plate
July 1995 increased activity caused evacuation
many evacuated to other Caribbean island or UK
april 1996 south of island was empty
lava was made from andesite and was so thick it didn’t flow
june 1997, erupted, 5 million cubic meters of lava
pyroclastic flows
killed 19 farmers, who were getting food for evacuated people
destroys settlements
the north changed from green to urban settlement bc they needed to support the evacuated people: housing
people are left making a living out of tourism to see the still smoking soufierre hill volcano

Question 23

seismic monitoring

Answer 23

detect movement of tectonic plates

Question 24

deformation monitoring

Answer 24

detect movement of ground on and around volcano

Question 25

environmental monitoring

Answer 25

assessing the gas and ash released and the effects on the environment

Question 26

volcano logical monitoring

Answer 26

observe the gravity lava dome and the chemistry of the lava