EOY TECTONICS PAPER 1

Question 1

what are the two types of volcanoes

Answer 1

shield and composite

Question 2

which plate boundary does not create volcanoes?

Answer 2

conservative

Question 3

what kind of volcanoes do divergent plate boundaries cause and how and describe this volcano

Answer 3

Shield. As plates move apart, magma rises through the gap. The magma is balsat and hot and runny. it forms fluid lava flows and shallow sided volcanoes.

basic lava, which is non-acidic and very runny
gentle sides as the lava flows for long distances before it solidifies
no layers, as the volcano just consists of lava
less violent eruptions
shorter periods between eruptions

Question 4

what kind of volcanoes do convergent plate boundaries cause and how and describe this volcano

Answer 4

composite. As the plates push together, oceanic plate is subducted. As it sinks, it melts and creates magma called andesite. Sea water is dragged down with it. This makes the magma less dense so it rises in plumes (or ‘blobs’) upwards through the continental crust. The water erupts as steam, making volcanoes very explosive. Volcanic ash and ‘bombs’ are blasted up and outwards as pyroclasts.

only between oceanic and continental … not anything else

Andesitic magma, which is lower in temperature, has more silica and a lot of dissolved gases and is more likely to explode when it reaches the surface.
Acidic lava, which is very viscous (sticky).
Steep sides as the lava doesn’t flow very far before it solidifies.
Alternate layers of ash and lava. For this reason, they’re also known as stratovolcanoes. Strato means layers.
Violent eruptions.
Longer periods between eruptions.

Question 5

Why are composite volcanoes more explosive than shield volcanoes?

Answer 5

Andesitic magma, which is lower in temperature, has more silica and a lot of dissolved gases and is more likely to explode when it reaches the surface. Acidic lava, which is very viscous (sticky). Steep sides as the lava doesn’t flow very far before it solidifies.

On the other hand, shield volcanoes are found at constructive plate boundaries and hotspots. Composite cone volcanoes are made of hardened layers of ash and lava, and have a steep, cone-like shape. Its lava has high levels of silica and a high viscosity which makes eruptions highly destructive.

Question 6

Volcanic eruptions are unpredictable. However, scientists can monitor volcanoes to estimate when they are likely to erupt. Scientists can use a variety of techniques to do this, such as

Answer 6

seismometers - used to measure earthquakes occurring near an eruption
tiltmeters and GPS satellites – these devices monitor any changes in landscape. Volcanoes tend to swell near an eruption
monitoring gases escaping from a volcano using robots called Spiders – often there is an increased release of sulphur dioxide near an eruption
measuring temperature - volcanoes become hotter when magma starts to rise through the main vent
looking at the past history of eruptions - scientists can identify patterns of activity

Question 7

talk about volcanoes on plumes

Answer 7

Hotspots are areas of volcanic activity that are not related to plate boundaries hot magma plumes from the mantle rise and going through weaker parts of the crust
This can create volcanoes in Ireland the plume stays in the same place but the plates continue to move which sometimes causes a chain of islands such as hawaii

Question 8

what is an earthquake

Answer 8

a sudden release of energy

Question 9

the power of an earthquake (how much the ground shakes) is known as the earthquakes what?

Answer 9

magnitude

Question 10

what does a seismometer measure for an earthquake

Answer 10

its magnitue

Question 11

how earthquake happens at a convergent boundary

Answer 11

tension builds up when one plate gets stuck as it’s moving down past the other into the mantleThe place eventually jerk past each other sending out shock waves (vibrations) these vibrations are the earthquake

Question 12

how earthquake happens at a divergent boundary

Answer 12

tension builds along cracks within the plates as they move away from each otherThe place eventually jerk past each other sending out shock waves (vibrations) these vibrations are the earthquake

Question 13

how earthquake happens at a conservative boundary

Answer 13

tension builds up when plates that are grinding past each other get stuckThe place eventually jerk past each other sending out shock waves (vibrations) these vibrations are the earthquake

Question 14

what is the focus of an earthquake

Answer 14

the point in the earth where the earthquake starts. This can be the earth’s surface or anywhere up to 700 km below the surface.

Question 15

what are shallow-focus earthquakes caused by

Answer 15

Tectonic plates moving at or near the surface they have a Focus between 0 KM and 70 km below the earth’s surface

Question 16

what are deep-focus earthquakes caused by

Answer 16

Buy crust that has previously been subducted into the mantle EG at the convergent plate boundaries moving towards the centre of the Earth heating up or decomposing they have a Focus between 70 km and 700 km below the earth’s surface

Question 17

in general, deeper earth quakes do 1) _____ _____ at the surface than 2)____ ____. Shock waves from deep earthquakes have to travel through more ___ to reach the surface , which 3) _____ their power (and the amount of shaking) when they reach the surface

Answer 17

1) less damage
2) shallow earthquakes
3) reduces

Question 18

what are tsunamis (revise on bottom of pg 22 gcp book)

Answer 18

a series of enormous waves caused when huge amounts of water get displaced