TECTONICS hazards definitions

Question 1

Degg’s Model

Answer 1

This model shows that a hazard becomes a disaster if it affects a vulnerable population.

Question 2

Epicentre

Answer 2

The point on the surface, directly above the earthquakes origin.

Question 3

Focus

Answer 3

The place in the crust where the pressure/seismic energy is released.

Question 4

Hazard mitigation cycle

Answer 4

The sequence of governance of a natural hazard: monitoring and prediction, mitigation(reduce severity), preparedness.

Question 5

Hot spot

Answer 5

Volcanoes found away from the plate boundary, due to a magma plume closer to the surface.

Question 6

Jokulhaup

Answer 6

A sudden glacial flood caused by a glacier on top of or near a volcano melting due to the heat from the eruption.

Question 7

Lahar

Answer 7

A flow of mud and debris

Question 8

Lithosphere

Answer 8

The upper crust of the earth (around 100km)

Question 9

Love waves

Answer 9

A surface earth wave with horizontal displacement

Question 10

Rayleigh waves

Answer 10

A surface earthquake causing horizontal and vertical displacement

Question 11

Convection currents

Answer 11

The circulation of magma within the mantle (asthenosphere). Magma is heated by radioactive processes in the core and cools at the surface, and so circulates between the two places.

Question 12

Asthenosphere

Answer 12

The upper mantle layer of the earth. It is semi molten and aprox 2000km wide

Question 13

Ash

Answer 13

Fine particles and dust ejected during an eruption, which can remain airborne as clouds or accumulate on the ground.

Question 14

Continental crust

Answer 14

Crust that forms the continents of the lithosphere, aprox 35km thick

Question 15

Continental drift

Answer 15

The movement of tectonic plates, due to varying weights of crust. It was originally thought that convection currents caused the movement o the plates but now slab pull is thought of as the primary driving force

Question 16

Mid- Ocean ridge

Answer 16

Parting oceanic plates at a constructive plate boundary creates a ridge, with new land at the base of the oceanic valley.

Question 17

Magnitude scale

Answer 17

A measure of an earthquake’s energy released considered the most accurate measure

Question 18

Oceanic crust

Answer 18

Crust usually thinner than continental crust that forms the sea floor aprox 7km thick

Question 19

Paleomagnetism

Answer 19

The alternating polarisation of new land created. As magma cools, the magnetic elements within will align with the Earth’s magnetic field, which can alternate over thousands of years.

Question 20

Park’s Model

Answer 20

A model describing the decline and recovery of a county over time, following a natural disaster.

Question 21

Primary waves

Answer 21

An earthquake wave causing compressions within the body of rocks

Question 22

Secondary waves

Answer 22

An earthquake wave causing vertical displacement within the body of rocks

Question 23

Richter scale

Answer 23

A logarithmic measure of earthquakes intensity

Question 24

Seismic waves

Answer 24

The energy released during an earthquake, in the form of primary, secondary, love and Rayleigh waves.

Question 25

Slab pull

Answer 25

The force contributing to the movement to tectonic plates. Slab pull is due to the weight of the plate.

Question 26

Subduction

Answer 26

Oceanic plate is forced below continental plate, due to the oceanic plate more dense than the continental plate

Question 27

Tsunami

Answer 27

Initial vertical water displacement (often from a submarine earthquake) creates waves, with large destructive power.

Question 28

Volcanic explosivity Index (VEI)

Answer 28

A measure of the magnitude of a volcano’s eruptions.

Question 29

Volcanic Island arc

Answer 29

A series of volcanoes ( often in the shape of an arc) that are formed consecutively, as a tectonic plate moves across a magma plume.

Question 30

Benioff zone

Answer 30

A region of the subduction plate, most affected by pressure and friction, where most destructive margin earthquakes originate.

Question 31

Pyroclastic flow

Answer 31

A mixture of gases and rock fragments, at high temperatures travelling at rapid speeds.