Tectonic Hazards GCSE

Epicenter

The point of the earth's surface directly above the focus of an earthquake

Plate Margin/Boundary

The area where tectonic plates meet

Continental Crust

Thick, not very dense crust that carries land

Oceanic Crust

Thinner, dense crust that carries oceans

Constructive Plate Boundary

Two plates moving away from each other causing magma to rise from the mantle, creating a new crust

Destructive Plate Boundary

Two plates moving towards each other often creating a subduction zone where an oceanic plate is pushed under a continental plate

Conservative Plate Boundary

Two plates are moving alongside each other, either passed each other or in the same direction but at different speeds

Collisional Plate Boundary

Two plates moving towards each other forming fold mountains

Primary Impacts

Immediate effects that happen during or just after the event

Secondary Impacts

Effects that take place a while after the event has taken place

Lahar

Mud flow mixed with water, lava, ash and dust.

Pyroclastic Flow

Mixture of hot steam, lava, ash and dust travelling at huge speeds

Focus

The point inside the crust where the pressure builds up most

Seismometer/Seismograph

An instrument that measures the impact of an earthquake by measuring the amount of energy it generates

Richter Scale

A scale that measures the magnitude of an earthquake (1-10)

Aftershocks

Smaller earthquakes and tremors that occur after the main earthquake

Tsunami

A huge wave usually caused by volcanic or earthquake activity under the sea

Volcanoes

Cone shaped hills or mountains formed by eruptions of lava and ash. Can occur at constructive and destructive plate boundaries

Tectonic Plates

Parts of the earths crust broken into several pieces that are in constant motion

Convection Currents

Radioactive decay in the earths core that causes hot circular convection currents to rise and fall causing the movement of tectonic plates

Magma

Molten Rock

Subduction Zone

When the less dense oceanic plate is forced under the more dense continental plate

Earthquakes

The shaking and vibration of the earth's crust due to movement of tectonic plates caused by the release of built-up pressure inside the earth's crust