TECTONICS

Question 1

Lithosphere

Answer 1

The surface layer of the earth is a rigid outer shell composed of the crust and upper mantle.

Question 2

Seismic hazards

Answer 2

Generated when rocks under surface come under such stress they break and become displaced.

Question 3

Intra-plate earthquakes

Answer 3

These occur in the middle or interior of tectonic plates and are much rarer than boundary earthquakes.

Question 4

Oceanic crust

Answer 4

Thin, composed of primarily basalt.

Question 5

Continental crust

Answer 5

Thicker, composed primarily of granite.

Question 6

Paleomagnetism

Answer 6

Results from the zone of magma ‘locking in’ or striking the earths magnetic polarity when it cools. Can be used to determine historic periods of large scale tectonic activity.

Question 7

Locked fault

Answer 7

A fault that is not slipping because of frictional resistance on the fault is greater than the stress across the fault, it is stuck.

Question 8

The Benioff zone

Answer 8

An area of seismicity corresponding with the slab being thrust downwards in subduction zone.

Question 9

Hypocentre

Answer 9

The focus point within the ground where the strain energy of the earthquake stored in the rock is first released.

Question 10

Locked fault

Answer 10

A fault that is not slipping because the frictional resistance on the fault is greater than the shear stress across the fault, that is, it is stuck.

Question 11

Soil liquefaction

Answer 11

The process by which water-saturated material can temporarily lose normal strength and behave like a liquid under the pressure of strong shaking.

Question 12

Intensity

Answer 12

A measure of the ground shaking.

Question 13

Magnitude

Answer 13

The magnitude of an earthquake is related to the amount of movement, or displacement, in the fault, which is in turn a measure of energy release.

Question 14

Epicentre

Answer 14

The location on the earth’s surface that is directly above the earthquake focus.

Question 15

Focus

Answer 15

The point where an earthquake originates.

Question 16

Fault

Answer 16

A fracture in the rocks that make up the earth’s crust.

Question 17

Seismic waves

Answer 17

Waves that transmit the energy released by an earthquake.

Question 18

Tectonic hazard profile

Answer 18

A technique used to try to understand the physical characteristics of different types of hazards. Also can be used to analyse and assess the same hazards at contrasting locations or at different times.

Question 19

Tectonic hazard profile criteria

6

Answer 19

Magnitude 
Speed of onset 
Duration 
Areal extent 
Spatial predictability 
Frequency

Question 20

Governance

Answer 20

The sum of the many ways individuals and institutions, public and private, manage their common affairs.

Question 21

Disaster hotspot

Answer 21

A country or area that is extremely disaster prone for a number of reasons.