Glossary

CDEM
Civil Defence and Emergency Management. The Ministry of CDEM leads the way in making New Zealand and its communities resilient to hazards and disasters.

civil defence
Steps taken by organised community groups for the protection of life and property in the event of a natural disaster.

continent
An enormous, unbroken area of land. Earth's surface is divided into Europe, Asia, Africa, North America, South America, Australia and Antarctica.

convection currents
Heat generated in the Earth’s core causes super-hot convection currents to circulate in the Earth’s mantle.

deforestation
The removal of a forest or stand of trees where the land is then converted to a non-forest use.

earthquake
A sudden movement of the Earth's crust caused by the release of stress accumulated along geologic faults or by volcanic activity.

emergency plan
The steps to take to reduce risk to yourself, your family and your property in the event of a natural disaster.

emergency services
The public organizations that respond to and deal with emergencies when they occur, especially the ambulance service, the police, and the fire brigade.

emergency supplies
A package of basic tools and supplies prepared in advance as an aid to survival in an emergency.

fault
A break in rock across which there is observable movement.

flood
A flood is an overflow of water that submerges land which is usually dry.

landslide
Movement of soil, rock and debris down a slope.

magma 
Molten rock beneath the Earth's surface.

magnitude
A measure of the energy released by an earthquake at its source. Magnitude is commonly determined from the shaking recorded on a seismograph. Each unit of magnitude on the scale represents a substantial increase in energy, for example a magnitude 6 releases 30 times more energy than a magnitude 5.

mantle 
Area of the Earth between the core and the crust.

Pacific Ring of Fire
The Ring of Fire is a major area in the basin of the Pacific Ocean where a large number of earthquakes and volcanic eruptions occur. In a 40,000 km (25,000 mi) horseshoe shape, it is associated with a nearly continuous series of oceanic trenches, volcanic arcs, and volcanic belts and/or plate movements.

plate boundaries
The edges of the plates that make up the crust of the Earth.

Plate tectonics
Plate tectonics is an explanation of how the surface of the Earth moves. 

subduction zone  
The area or zone where two tectonic plates come together, one riding over the other.

tectonic plates
Blocks of the Earth's continental and oceanic crust that move, float, and sometimes fracture. Their interaction causes continental drift, earthquakes, volcanoes, mountains, and oceanic trenches.

seismic waves
The waves of energy released by an earthquake.

storm
a disturbance of the atmosphere that can cause strong winds, rain, thunder, lightning, heavy snow and rough seas.

tsunami
A series of powerful ocean surges caused by a large volume of the ocean floor being displaced – often by an undersea earthquake or landslide.

volcano
A volcano is a vent at the Earth's surface through which magma and volcanic gases erupt. It is also the cone built by effusive and phreatic eruptions.