Tectonitc

Question 1

Earthquake distribution and causes

Answer 1

Distribution
-near tectonic boundaries
-pacific ring of fire
- old fault lines e.g - church Stretton fault
- most powerful in convergent, conservative plate boundaries. + imtraplate earthquakes

Causes
- caused by sudden release of
- as plates move past they inevitably ‘stick’
-causes build up of stress and strain
- pressure is suddenly released
- pulse of energy radiates in all directions from focus

Question 2

Volcano distribution + causes

Answer 2

Distribution
- close to tectonic boundaries and hotspots
- pacific ring of fire
-500 active volcanoes
-50 erupt per year
- determined by dissolved gasses in magma

Causes
- divergent + convergent plate boundaries
-hotspots

Question 3

Tsunami causes and distribution

Answer 3

Distribution
-90% occur in pacific basin
-subduction zone e.g - off the Japan Taiwan island arc

Causes
-submarine earthquakes displace seabed vertically
- motion displaces ocean water column

Question 4

Constructive (divergent) plate boundaries

Answer 4

Oceanic - oceanic
- magma rises between gap = new land formed when cooled
- less explosive underwater volcanoes
- new land is formed

Continental - continental
- land is forced apart = rift valley
- volcanoes form where magma rises
- gap will fill with water eventually
E,g African rift valley

Question 5

Destructive (convergent) plate boundary

Answer 5

Heavier( denser plate subducts lighter plate
Explosive volcanoes formed

Collision
- no subduction so fold mountains e,g - Himalayas

Question 6

Conservative plate boundary

Answer 6

Plates slide past each other
Earthquakes

San Andreas

Question 7

Causes of intraplate earthquakes

Answer 7

Can occur in mid plate settings associated with major ancient fault lines being activated due to tectonic stress

Question 8

Hotspot volcanoes

Answer 8

Eruptions occur around plate boundaries and hotspots
Middle of tectonic plates
Mantle plumes rise towards surface generating basaltic volcanoes
As tectonic plates move over hotspot, volcanoes move away, new ones form. Volcanic islands

Question 9

Earths internal structure

Answer 9

Crust- oceanic (thin, young, basaltic, dense) continental (thick, old, granitic, less dense)

Lithosphere ( crust + upper mantle)

Mantle (