Key Terms: Tectonic Hazards (AQA GCSE Geography): Revision Note

Tectonic hazards - key terms glossary

Aftershock – A smaller earthquake that occurs after a larger earthquake, potentially causing further damage.

Collision boundary – A type of plate boundary where two continental plates push against each other, causing earthquakes and land to fold.

Conservative (transform) boundary – A plate boundary where two tectonic plates slide past each other; this causes earthquakes but not volcanoes.

Constructive plate boundary – A boundary where tectonic plates move apart, allowing magma to rise and create new crust, often forming volcanoes.

Continental crust – The thicker, older and less dense part of the Earth's crust, making up the land masses.

Crust – The Earth’s outermost layer, made up of oceanic and continental plates.

Destructive plate boundary – A boundary where an oceanic plate sinks below a continental plate, generating friction, melting rock, and causing volcanic eruptions and earthquakes.

Epicentre – The point directly above the focus of an earthquake on the Earth's surface.

Focus – The underground point where an earthquake originates.

Gas emissions – The release of gases, such as sulphur dioxide or radon, often linked to volcanic activity.

Hotspot – A volcanic area located away from plate boundaries where magma rises through the crust.

Inner core – The solid innermost part of the Earth, made mainly of iron and nickel, with temperatures around 5500°C.

Lahar – A fast-moving volcanic mudflow formed when ash mixes with water.

Landslide – The movement of rock and soil down a slope, often triggered by tectonic activity.

Lava – Molten rock that erupts from a volcano and solidifies on the Earth's surface.

Mantle – A semi-molten layer beneath the crust that moves slowly and causes tectonic plate motion.

Oceanic crust – The thinner, denser part of the Earth's crust found beneath oceans.

Plate boundary (or margin) – The area where two tectonic plates meet and where most tectonic activity occurs.

Plate tectonics – The scientific theory that explains the movement of the Earth’s crustal plates and associated phenomena like earthquakes and volcanoes.

Primary effects – The direct consequences of a tectonic event, such as lava flow or buildings collapsing.

Pyroclastic flow – A very hot, fast-moving flow of ash and gases that rushes down the side of a volcano.

Seismic waves – Vibrations that spread out from the earthquake focus and cause shaking.

Seismometer – A device that detects and records the strength and duration of earthquakes.

Slab pull theory – The idea that the weight of a subducting plate helps to drag the rest of the tectonic plate behind it.

Soil liquefaction – The process where solid ground turns into a liquid-like state during an earthquake.

Subduction – The process where a denser oceanic plate moves under a lighter continental plate and is forced into the mantle.

Tectonic plates – Large slabs of the Earth’s crust that float on the mantle and cause geological activity when they move.

Tsunami – A large, powerful sea wave caused by an underwater earthquake or volcanic eruption.

Volcanic bomb – A large rock fragment ejected during a volcanic eruption that solidifies in mid-air.

Volcanic eruption – The release of lava, ash, and gases from a volcano onto the Earth’s surface.

Volcano – A mountain formed by eruptions of lava and ash from a central vent.

Response to natural hazards - key terms glossary

Aid – Emergency help provided after a disaster, including money, food, medical supplies, and rescue workers.

Emergency shelter – Temporary housing provided to people who have lost their homes due to a hazard.

Immediate response – Actions taken right after a hazard event, such as rescue efforts, first aid, and providing food and water.

Long-term response – Rebuilding and recovery efforts that happen over months or years after a hazard, including infrastructure and housing.

Primary effects – Direct impacts from the hazard, like collapsed buildings or lava damage.

Secondary effects – The indirect effects that happen as a result of the primary impacts, like homelessness, fires, or disease.

Rebuilding – The process of constructing new homes, schools, and roads after they have been damaged or destroyed by a hazard.

Rescue teams – Groups of trained personnel who respond quickly to search for and help survivors.

Management of tectonic hazards - key terms glossary

Evacuation plan – A strategy to move people away from danger zones before a hazard event occurs.

Exclusion zone – An area declared unsafe where people are not allowed to enter due to risk from a hazard.

Geothermal energy – Renewable energy created from heat beneath the Earth’s surface, often found in tectonic regions.

Hazard mapping – Creating maps that identify areas most at risk from hazards like earthquakes or volcanic eruptions.

Monitoring – The use of scientific instruments (e.g. seismometers, gas sensors, satellites) to track signs of tectonic activity.

Planning – Strategies to prepare communities for hazard events, including drills, emergency kits, and education.

Prediction – Using scientific data to try to forecast when and where a tectonic hazard might happen.

Preparedness – Measures taken before a hazard to ensure people and infrastructure are ready, such as drills and stockpiling supplies.

Protection – Efforts to make buildings and infrastructure safer, such as earthquake-resistant design or sea walls for tsunamis.

Tiltmeter – A device that detects slight changes in the ground's shape, often used to monitor volcanoes.

Training – Educating emergency services and the public on what to do in the event of a hazard.