Natural Hazards Knowledge Organiser

Comprehensive vocabulary flashcards covering the Autumn 1 Natural Hazards Knowledge Organiser, including hazard risks, plate tectonics, case studies of Haiti (2010) and Japan (2011), and hazard management.

Natural hazard

A natural event (such as an earthquake, volcanic eruption, tropical storm, or flood) that threatens people or has the potential to cause damage, destruction, and death.

Hazard risk

The probability or chance that a natural hazard may take place.

Hazard Type

A factor affecting hazard risk that relates to the severity, scale, and frequency of the event (e.g., magnitude of an earthquake).

Exposure

A factor affecting hazard risk defined by the number of people and the value of property located in hazard-prone areas.

Vulnerability

The capacity of a community to cope with, resist, and recover from a hazard (e.g., building standards, early warning systems, and economic development).

Plate tectonics theory

The theory stating that the Earth's crust is broken into large pieces called tectonic plates, which float on the semi-molten mantle beneath them and move very slowly due to convection currents inside the Earth.

Tectonic plate

A rigid segment of the Earth’s crust which moves across the heavier, semi-molten rock below. Continental crust is less dense but thicker than oceanic crust.

Plate margin

The margin (or boundary) between two tectonic plates.

Igneous rocks

Rocks formed when magma or lava cools and solidifies inside the Earth or after a volcanic eruption.

Sedimentary rocks

Rocks formed when sediments are deposited in layers and compacted or cemented over time, usually in rivers, lakes, or oceans.

Metamorphic rocks

Existing rocks that are changed by heat and pressure, often deep underground or at plate boundaries.

Pacific "Ring of Fire"

The famous narrow band tracing the edges of the Earth's tectonic plates where the majority of earthquakes and volcanoes occur.

Hotspots

Locations where volcanic activity can occur away from plate margins, including in the middle of tectonic plates (e.g., The Hawaiian Islands).

Constructive plate margin

A plate margin where tectonic plates move apart (diverge) and rising magma fills the gap, cooling to create new crust and volcanoes, with earthquakes occurring as the plates pull apart.

Destructive plate margin

A plate margin where two plates collide (converge) and the heavier oceanic plate is subducted under the lighter continental plate, melting into magma that rises to cause violent volcanic eruptions and powerful earthquakes.

Subduction

The process occurring at destructive margins where the heavier oceanic plate is forced beneath the lighter continental plate and sinks into the mantle.

Conservative plate margin

A tectonic plate margin where two plates slide past each other at different speeds; friction causes them to get stuck until built-up pressure suddenly releases, causing severe earthquakes without volcanic activity.

Earthquake

A sudden or violent movement within the Earth’s crust followed by a series of shocks.

Volcano

An opening in the Earth’s crust from which lava, ash, and gases erupt.

Tectonic hazard

A natural hazard caused by the movement of tectonic plates, including volcanoes and earthquakes.

Primary effects

The initial impact of a natural event on people and property caused directly by it, such as ground shaking and buildings collapsing following an earthquake.

Secondary effects

The after-effects that occur as indirect impacts of a natural event, sometimes on a longer timescale, such as fires due to ruptured gas mains resulting from ground shaking.

Immediate responses

The reaction of people as the disaster happens and in the immediate aftermath.

Long-term responses

Later reactions and recovery actions that occur in the weeks, months, and years after the event.

Haiti Earthquake (2010)

A magnitude $7.0$ earthquake on 12 January 2010 near Port-au-Prince in an LIC that killed around $230{,}000$ people, injured $300{,}000$, displaced $1.3\text{ million}$, and cost an estimated $8\text{--}14\text{ billion dollars}$.

Japan (Tohoku) Earthquake and Tsunami (2011)

A magnitude $9.0$ earthquake and up to $40\text{-metre}$ tsunami on 11 March 2011 in an HIC that killed $19{,}759$ people, caused the Fukushima nuclear disaster, and created economic losses exceeding $200\text{ billion dollars}$.

Monitoring

Recording physical changes, such as using seismometers to track earth tremors and detect ground deformation or gas releases, to help forecast when and where a hazard might strike.

Prediction

Attempts to forecast when and where a natural hazard might strike using monitored data; can be done effectively for volcanic eruptions, but less reliably for earthquakes.

Protection

Actions taken before a hazard strikes to modify the built environment (such as reinforced steel frames and rubber shock absorbers) or educate people to reduce damage and save lives.

Planning

Creating strategies before and during an event to enable communities to respond and recover, including hazard mapping, running evacuation drills, and packing emergency supply kits.

Geothermal Energy

A constant, renewable source of energy and hot water provided by magma located close to the Earth's surface in tectonic areas (e.g., in Iceland).