Science: Earth

The three types of rock are: Igneous, Sedimentary and Metamorphic.

Igneous rocks are formed from the cooling of molten rock from volcanic eruptions. The igneous rocks weather and layer upon each other forming sedimentary rocks. The sedimentary rocks are then put under extreme pressure and have added temperature, causing the minerals inside of them to re-crystalize forming metamorphic rocks.

A volcano is a weakness in the earths crust which allows magma to push up to the surface.

Shield, Dome, Caldera and Cone.

NZ has a lot of volcanoes because it sits on the Pacific Ring of Fire.

Geysers, hot pools and fumaroles.

It is the edge of the Pacific Plate where volcanoes are really common.

A shield volcano is formed from basaltic magma. It is a low cone sloping shape and deposits runny lava. A NZ example is Mt Akaroa and has more gentle explosions.

A cone volcano is formed from andesitic magma and has steep cone sides. It deposits sticky lava in more ashy and explosive eruptions. A NZ example is Mt Taranaki.

Shield volcanoes are formed from rhyolitic magma. They are dome shaped and deposit stick lava in sudden explosions. A NZ example is Mt Tarawera.

Caldera Volcanoes are formed from rhyolitic magma. They are holes left after very violent volcanoes. They deposit stick lava in very violent eruptions that occur due to built up pressure. A NZ example is Lake Taupo.

Is the most destructive wave, is the last to be felt and occurs at the surface. Causes the jelly like movement.

The focus is where the movement occurs beneath the earths crust.

The epicenter is the point on the Earths crust directly above the focus.

The first wave to be felt. Caused by a longitudinal wave and produce push and pull movements. It is the fastest wave and can travel through solids and liquids.

It is also called a shear wave. The second to be felt, is caused by transverse waves. Produces up and down, side to side movement. It can only travel through solids.

If the earthquake is detected by three or more seismographs, the position of the epicenter can be found.

Describes the energy carried by an earthquake. It gives a number from 1 up to but never reaching 9 (as it is thought to be impossible to have an earthquake of this magnitude). Each higher number carries 10x the energy of the number below it. So 6 is 10x greater than 5. And 7 is 100x greater than 5.

Because it is partly on the Pacific plate and partly on the Indo-Australian plate. There are several fault lines running through NZ.

An L wave is a surface wave, it causes the earth to shake like jelly and causes the most damage. It is the slowest wave.

The theory that giant sections or plates of rock are moving across the Earths surface. It replaces the continental drift theory, in which only the continents were thought to be moving. Convection currents cause the movement of the plates.

The Earths crustal plates are moving in all directions at around 4cm per year.

Mid Oceanic Ridges.

Earthquakes

Deep mid-oceanic trenches; volcanic activity; faults and mountain building.

NZ lies over an active subduction zone, where rocks of the pacific plate are being pushed under the rocks of the indo-australian plate. This causes: earthquakes, volcanoes and hot springs to be present along the plates boundaries.