Causes Of Tectonic Hazards

Question 1

Benioff zone

Answer 1

A zone of earthquakes located along the subduction zone
It is a MODEL

Question 2

Why is the discovery of the Benioff zone important?

Answer 2

Before it’s discovery, earthquakes were believed to be randomly distributed across the earth
We now know that most earthquakes occur in narrow zones. The Benioff zone is a model used to highlight where earthquakes occur along destructive plate boundaries
Benioff zones occur within the subduction zone/area between continental crust and oceanic crust

Question 3

What are fault lines

Answer 3

Huge cracks in the earth where two tectonic plates meet
San Andreas fault - example
Two plates meet for long time building up pressure

Question 4

P waves

Answer 4

Pulse waves
Front to back

Question 5

S waves

Answer 5

Shear waves
Left to right

Question 6

% of energy released in earthquak

Answer 6

95% of energy is released in first 10 seconds

Question 7

What are the main cause of earthquake deaths

Answer 7

Buildings are the main cause of deaths

Question 8

Causes of earthquakes

Answer 8

The movement of plates are preceded by a gradual build up of tectonic strain, which stores elastic energy in crustal rocks

Question 9

Simple causes of an earthquake

Answer 9

Two plates meet each other
The plates eventually jerk past each other sending out shock waves (vibrations from the focus of an earthquake)
The shock waves spread out from the focus (point in the earth where the earthquake starts) near the focus the waves are stronger and cause more damage
The ground shakes the strongest at the epicentre

Question 10

Epicentre

Answer 10

Point on the earths surface straight above focus

Question 11

Aftershocks

Answer 11

Small tremors after an earthquake

Question 12

Shallow focus result

Answer 12

Result in more damage as rocks and plates buckle, deform and fault (0-70km deep)
-75% of all earthquake energy released