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Glossary

 

 

Australian Plate

– Australia and the North Island and western South Island of New Zealand sits on this tectonic plate. It is sometimes called the Indo-Australian Plate.

Coastal margin

– The area between land and sea.

Convection currents

 The movement of rock within the mantle caused by the heat of the core. The rock rises as it heats and then falls back towards the core when it cools.

Convergent boundary

– Where two tectonic plates push together.  

Crust

 The outermost layer of the Earth. The crust is around 5 – 70km thick.

Divergent boundary

– Where two tectonic plates move away from each other.

Earthquakes

 A sudden shaking of the ground as a result of tectonic plates moving.

Epicentre

 The point on the Earth’s surface where the earthquake occurs.

Fault rupture

 A break in the ground along the fault line during an earthquake. 

Liquefaction

 Liquefaction happens when underground water in the soil comes to the surface. Thick muddy slush spreads everywhere, causing buildings and other structures to sink into the ground.

Lithosphere

– Is made up of the Earth's crust and the upper part of the mantle. 

Magma

- Molten or partly molten rock below the Earth’s surface. Magma that reaches the surface erupts as lava or rock from a volcano.

Mantle

– The area of the Earth between the core (on its inner surface) and the crust (on its outer).

Molten

– Something that becomes a liquid when heated.

Natural hazards

 A naturally occurring event that can have a negative effect on people or the environment eg. an earthquake, tsunami or volcanic eruption

Pacific Plate

 The eastern South Island of New Zealand and the Pacific Ocean sits on this plate.

Plate boundary

– Where two tectonic plates.

Primary effects

 occur as a direct result of the ground shaking, eg buildings collapsing.

Resilience

 The capacity to recover quickly from difficulties.

Return period

 The average time between natural hazard events.

Richter scale

– A scale that measures the strength of an earthquake.

Risk

– The likelihood of being negatively impacted by an event eg. Natural hazard.

Sea level

 The level of the ocean's surface to land, usually measured as the level halfway between mean high and low tide.

Subduction

– The downward movement of one tectonic plate beneath another tectonic plate.  This is where volcanoes usually form.

Tectonic plates

– Pieces of the earth’s crust and upper mantle (lithosphere) that are continually moving. This movement is most obvious at the boundaries between the tectonic plates.

The Modified Mercalli Intensity (MMI)

 A scale that measures the intensity of an earthquake.

Transform boundaries

– Where two tectonic plates slide in opposite directions against each other.

Trench

 A long and deep dip on the ocean floor which indicates a subduction plate boundary eg. Hikurangi trench.

Tsunami

 A long, high and powerful sea wave caused by an earthquake or other disturbance.

Volcano

– Mountain or hill with a crater or vent through which magma and gases erupt from the earth's surface.