hazard 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. It is semi-molten and approximately 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 Drift

Answer 5

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

Question 6

Controlled Burning

Answer 6

Intentionally burning vegetation with the aim of reducing fuel available for a
wildfire and disrupting the fire’s path

Question 7

Continental Crust

Answer 7

Crust that forms the continents of the lithosphere, on average 35km thick.

Question 8

Convection Currents

Answer 8

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 9

Coriolis Effect

Answer 9

The Earth’s spin affects the movement of air masses and winds, depending on a
location’s latitude.

Question 9

Crown Fires

Answer 9

Wildfires that burn the entirety of a tree (from top to bottom), often the most
destructive and dangerous type of wildfire.

Question 10

Degg’s Model

Answer 10

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

Question 11

Epicentre

Answer 11

The point on the surface, directly above the earthquake’s origin.

Question 12

Fatalism

Answer 12

The belief that hazards are uncontrollable, so any losses should be accepted and
mitigation is unnecessary.

Question 13

Fire Breaks

Answer 13

The felling of trees and clearing vegetation to create a gap to disrupt a wildfire’s path.

Question 14

Focus

Answer 14

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

Question 15

Ground Fires

Answer 15

Wildfires that burn through the peat and vegetation beneath the surface, making
them slow but difficult to extinguish.

Question 16

Hazard Management Cycle

Answer 16

The sequence of governance of a natural hazard: preparedness,
response, recovery, and mitigation.

Question 17

Hot Spot

Answer 17

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

Question 18

Jokulhaup

Answer 18

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

Question 19

Lahar

Answer 19

A flow of mud and debris

Question 20

Lithosphere

Answer 20

The upper crust of the Earth (average thickness = 100km)

Question 21

Love Waves

Answer 21

A surface earthquake wave with horizontal displacement.

Question 22

Mid-Ocean Ridge

Answer 22

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

Question 23

Moment Magnitude Scale

Answer 23

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

Question 24

Oceanic Crust

Answer 24

Crust, usually thinner than continental crust, that forms the sea floor. It is on average 7km thick.

Question 25

Paleomagnetism

Answer 25

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 26

Park’s Model

Answer 26

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

Question 27

Partial Melting

Answer 27

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

Question 28

Primary Waves

Answer 28

An earthquake wave causing compressions within the body of rock.

Question 29

Richter Scale

Answer 29

A logarithmic measure of earthquake’s intensity.

Question 30

Pyroclastic Flow

Answer 30

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

Question 31

Rayleigh Waves

Answer 31

A surface earthquake wave causing both horizontal and vertical displacement.

Question 32

Secondary Waves

Answer 32

An earthquake wave causing vertical displacement within the body of rock.

Question 33

Seismic Waves

Answer 33

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

Question 34

Slab Pull

Answer 34

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

Question 35

Subduction

Answer 35

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

Question 35

Surface Fires

Answer 35

Wildfires that only burn the leaf litter, and so are the easiest kind to extinguish.

Question 36

Volcanic Explosivity Index (VEI)

Answer 36

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

Question 36

Tropical Storm

Answer 36

A low pressure system of spiralling winds (due to the Coriolis Effect). Also called hurricanes, cyclones, and typhoons depending on the location they occur in.

Question 37

Tsunami

Answer 37

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

Question 38

Volcanic Island Arc

Answer 38

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 39

Wadati-Benioff Zone

Answer 39

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

Question 40

Wildfire

Answer 40

A large, uncontrolled fire that quickly spreads through vegetation