Hazardous Earth key terms

Question 1

Aftershocks

Answer 1

Follow an earthquake as the fault ‘settles’ into its new position.

Question 2

Andesitic Lava

Answer 2

A thick and sticky lava erupted from composite volcanoes.

Question 3

Asthenosphere

Answer 3

Part of the Earth’s mantle. It is a hot, semi-molten layer that lies beneath the tectonic plates.

Question 4

Atmosphere

Answer 4

The layer of gases above the Earth’s surface.

Question 5

Basalt

Answer 5

A dark-coloured volcanic rock, Molten basalt spreads rapidly and is widespread.

Question 6

Collision zone

Answer 6

Where two tectonic plates collide - forming mountains like the Himalayas.

Question 7

Composite Volcano

Answer 7

A steep-side volcano that is made up of a variety of materials, such as lava and ash.

Question 8

Conservative boundary

Answer 8

Where two tectonic plates slide past each other.

Question 9

Continental crust

Answer 9

The part of the Earth that makes up land, on average 30-50km thick

Question 10

Convection currents

Answer 10

Transfer heat from one part of a liquid or gas to another. In the Earth’s mantle, the currents which rise from the Earth’s core are strong enough to move the tectonic plates on Earth’s surface.

Question 11

Convergent boundary

Answer 11

Where two tectonic plates come together.

Question 12

Core

Answer 12

The central part of the Earth’s structure, made up of a solid inner and liquid outer core.

Question 13

Coriolis force

Answer 13

A strong force created by the Earth’s rotation. It can cause storms, including hurricanes.

Question 14

Distribution

Answer 14

The way something is spread out or arranged over a geographic area.

Question 15

Divergent boundary

Answer 15

Where two tectonic plates move away from each other.

Question 16

Effusive

Answer 16

A type of eruption where runny lava flows steadily out of a fissure or
vent.

Question 17

Epicentre

Answer 17

The point on the ground directly above the focus (centre) of an
earthquake.

Question 18

Eye

Answer 18

The centre of a tropical cyclone; an area of clear conditions created by
air converging at the centre of the storm and then sinking.

Question 19

Fault

Answer 19

Large cracks caused by past tectonic movement.

Question 20

Focus

Answer 20

The point of origin of an earthquake.

Question 21

Friction

Answer 21

The force which resists the movement of one surface over another.

Question 22

Glacial

Answer 22

A cold period of time during which the Earth’s glaciers expanded widely.

Question 23

Global atmospheric circulation model

Answer 23

A theory that explains how the atmosphere operates in a series of three
cells each side of the equator.

Question 24

Greenhouse effect

Answer 24

The way that gases in the atmosphere trap heat from the sun. Like the
glass in a greenhouse – they let heat in, but prevent most of it from
escaping.

Question 25

Greenhouse gases

Answer 25

Gases like carbon dioxide and methane that trap heat around the Earth, leading to global warming.

Question 26

Hot spot

Answer 26

Columns of heat in Earth’s mantle found in the middle of a tectonic plate.

Question 27

Interglacial

Answer 27

A long period of warmer conditions between glacials.

Question 28

Inter-Tropical Convergence Zone (ITCZ)

Answer 28

A narrow zone of low pressure near the Equator where northern and southern air masses converge.

Question 29

Landslide

Answer 29

A rapid mass movement of rock fragments and soil under the influence of gravity.

Question 30

Latitude

Answer 30

How far north or south a location is from the Equator, measured in degrees.

Question 31

Lava

Answer 31

Melted rock that erupts from a volcano.

Question 32

Lava flows

Answer 32

Lava flows at different speeds, depending on what it is made of. Lava flows are normally very slow and not hazardous but, when mixed with water, can flow very fast and be dangerous.

Question 33

Lithosphere

Answer 33

The uppermost layer of the Earth. It is cool and brittle. It includes the very top of the mantle and, above this, the crust.

Question 34

Magma

Answer 34

Melted rock below the Earth’s surface. When it reaches the surface it is called lava.

Question 35

Magnitude

Answer 35

Of an Earthquake (how much the ground shakes), an expression of the total energy released.

Question 36

Mantle

Answer 36

The middle layer of the Earth. It lies between the crust and the core and is about 2900km thick. Its outer layer is the asthenosphere. Below the asthenosphere it consists mainly of solid rock.

Question 37

Milankovitch Cycles (orbital change)

Answer 37

The three long-term cycles in the Earth’s orbit around the sun.

Question 38

Ocean currents

Answer 38

Permanent or semi-permanent large-scale horizontal movements of the ocean waters.

Question 39

Oceanic crust

Answer 39

The part of the Earth’ crust which is under the oceans, usually 6-8km thick.

Question 40

Plate boundaries

Answer 40

Where tectonic plates meet. There are 3 kinds: divergent, convergent and conservative.

Question 41

Plumes

Answer 41

Upwelling of molten rock through the asthenosphere to the lithosphere.

Question 42

Primary effects

Answer 42

The immediate effects of a natural hazard, caused directly by it.

Question 43

Pyroclastic flow

Answer 43

A lethal hot mixture of broken rocks and gases that races down the side of a volcano.

Question 44

Quaternary

Answer 44

Most recent period of geological time: The last 2.6 million years, during which there have been many glacials.

Question 45

Radioactive decay

Answer 45

The process where natural radioactive materials in the Earth’s rocks break down, giving out energy and heat as they do.

Question 46

Richter scale

Answer 46

A scale for measuring the magnitude of earthquakes.

Question 47

Remote sensing

Answer 47

Using satellites or aerial photography to provide information on land use over large areas.

Question 48

Saffir-Simpson Hurricane Scale

Answer 48

A scale that classifies hurricanes into five different categories according to their wind strength.

Question 49

Secondary effects

Answer 49

The indirect impacts of an event , usually occurring in the hours, weeks, months or even years after the event.

Question 50

Seismometer

Answer 50

A machine for recording and measuring an earthquake using the Richter scale.

Question 51

Storm surge

Answer 51

A rapid rise in the level of the sea caused by low pressure and strong winds.

Question 52

Subduction

Answer 52

Describes oceanic crust sinking into the mantle at a convergent plate boundary. As the crust subducts, it melts back into the mantle.

Question 53

Tectonic hazards

Answer 53

Natural events caused by movement of the Earth’s plates that affect people and property. Earthquakes, volcanoes and tsunamis (tropical storms are NOT tectonic hazards)

Question 54

Tectonic plates

Answer 54

The Earth’s surface is broken into large pieces, like a cracked eggshell. The pieces are called tectonic plates, or just plates.

Question 55

Thermal expansion

Answer 55

As a result of heating, expansion occurs. When sea water waters up, it expands.

Question 56

Track

Answer 56

The path followed by a tropical cyclone.

Question 57

Tree rings

Answer 57

Marks on the inside of trees trunks that show individual growing seasons. The thickness of the rings varies depending on climatic conditions during the seasons.

Question 58

Tropical cyclone

Answer 58

A weather system that forms over the ocean in tropical areas and can produce high winds and heavy rain.

Question 59

Tsunami

Answer 59

Earthquakes beneath the sea bed generate huge waves that travel up to 900km/h.

Question 60

Volcanic Explosivity Index (VEI)

Answer 60

Measures the explosiveness of volcanic eruptions on a scale of 1 to 8.