1.1 Causes of Tectonic Hazards

Question 1

1. 1a The Distribution and Causes of Tectonic Hazards

earthquakes: distribution

Answer 1

most earthquake zones are found at, or close to, tectonic plate boundaries, often in clusters

around 70% of all earthquakes occur along the ‘Ring of Fire’ in the Pacific Ocean

the most powerful earthquakes are associated with convergent and conservative plate boundaries

some intra-play earthquakes do not occur at plate boundaries due to hot spots

Question 2

1. 1a The Distribution and Causes of Tectonic Hazards

earthquakes: causes

Answer 2

Earthquakes are sudden releases of stored energy known as ‘slip-stick behaviour’

As two plates move past each other they can lock, allowing energy to build up over time and the plates are placed under increasing stress. the sudden release of stress creates a pulse of energy that radiates out in all directions from the earthquake focus

Question 3

1.1a The Distribution and Causes of Tectonic Hazards

volcanic eruptions: distribution

Answer 3

a

Question 4

1.1a The Distribution and Causes of Tectonic Hazards

volcanic eruptions: causes

Answer 4

a

Question 5

1. 1a The Distribution and Causes of Tectonic Hazards

tsunami: distribution

Answer 5

90% of all tsunami events occur within the Pacific Basin, associated with activity at the plate boundaries

most tsunamis are generated at subduction zones

Question 6

1. 1a The Distribution and Causes of Tectonic Hazards

tsunami: causes

Answer 6

tsunamis are generated when a sub-main earthquake displaces the sea bed vertically as a result of movement along a fault line at a subduction zone

the violent motion displaces a large volume of water in the ocean water column, which then moves outwards in all directions from the point of displacement

at subduction zones, tectonic recoil of the subjected plate causes severe earthquakes