Tectonic definitions

Question 1

Accretion wedge

Answer 1

The accumulation of material at the point of subduction

Question 2

Aseismic buildings

Answer 2

Buildings designed to withstand or minimise destruction during an earthquake

Question 3

Asthenosphere

Answer 3

The upper mantle layer of the Earth- semimolte, 2000km wide

Question 4

Ash

Answer 4

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

Question 5

Continental crust

Answer 5

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

Question 6

Continental drift

Answer 6

The movement of tectonic plates, due to varying weights of the crust- slab pull is the driving force

Question 7

Degg’s model

Answer 7

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

Question 8

Epicentre

Answer 8

The point on the surface, directly above the earthquakes origin

Question 9

Focus

Answer 9

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

Question 10

Hazard mitigation cycle

Answer 10

The sequence of governance of a natural hazard- monitoring & prediction, mitigation and preparedness

Question 11

Mitigation

Answer 11

Reducing risk of harm or minimising losses

Question 12

Hot spot

Answer 12

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

Question 13

Jokulhaup

Answer 13

A sudden glacial flood caused by a glacier on top of or near a volcano that melts due to the heat of the eruption

Question 14

Lahar

Answer 14

A flow of mud and debris

Question 15

Lithosphere

Answer 15

The upper crust of the earth, around 100km thick

Question 16

Love waves

Answer 16

A surface earthquake wave with a horizontal displacement

Question 17

Mid-ocean ridge

Answer 17

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

Question 18

Moment magnitude scale

Answer 18

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

Question 19

Oceanic crust

Answer 19

Crust, usually thinner than continental crust, that forms the sea floor- around 7km thick

Question 20

Paleomagnetism

Answer 20

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

Question 21

Park’s model

Answer 21

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

Question 22

Partial melting

Answer 22

Elements within the lithosphere have different melting points, and so rock is partially melted, partially solid

Question 23

Primary waves

Answer 23

An earthquake wave causing compressions within the body of rock

Question 24

Pyroclastic flow

Answer 24

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

Question 25

Rayleigh waves

Answer 25

A surface earthquake wave causing both vertical and horizontal displacement

Question 26

Richter scale

Answer 26

A logarithmic measure of an earthquake’s intensity

Question 27

Secondary waves

Answer 27

An earthquake wave causing vertical displacement within the body of rock

Question 28

Seismic waves

Answer 28

The energy released during an earthquake, in the form of Primary, Secondary, Love and Rayleigh waves

Question 29

Slab pull

Answer 29

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

Question 30

Subduction

Answer 30

Oceanic plate is forced below continental plate, due to the oceanic plate being denser

Question 31

Tsunami

Answer 31

Initial veritcal water displacement creates waves, with large destructive power

Question 32

VEI

Answer 32

Volcanic Explosivity Index
- A measure of the magnitude of a volcano’s eruptions

Question 33

Volcanic Island Arc

Answer 33

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

Question 34

Wadati-Benioff Zone

Answer 34

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