Natural hazard zones

A natural hazard is a natural process or event that could cause loss of life, injury, damage to property or disruption to environments. A disaster is what happens when a hazard actually strikes an exposed and vulnerable community and overwhelms its ability to cope. Geographers group hazard-generating processes by where their energy comes from.

Geological processes operate within the earth: tectonic plates move, strain builds up along faults and is released as earthquakes, and magma generated at subduction zones and hotspots rises to produce volcanic eruptions. Geomorphic processes operate on the earth's surface: gravity moves rock and soil downslope as landslides and debris flows, rivers overtop their banks and spread across floodplains, and waves erode coasts. Atmospheric processes involve the movement of heat, air and moisture, producing tropical cyclones, severe thunderstorms, heatwaves and drought.

Many disasters combine processes. An undersea earthquake (geological) can lift a column of seawater and send a tsunami onto a coast. A tropical cyclone (atmospheric) can drop days of heavy rain that saturates hillslopes and triggers landslides (geomorphic). Tracing the chain of processes matters because each link creates its own hazard zone and needs its own response.

The syllabus expects these processes to be shown visually as well as in words. A conceptual model simplifies a process into labelled stages, for example warm ocean water, rising moist air, release of latent heat and intensification of a cyclone. A block diagram shows surface and subsurface together, so a subduction zone can display the ocean trench, the sinking plate and the arc of volcanoes inland.

A cross-section or profile drawn from contour lines reveals slope steepness and the paths that water, debris or lava are likely to follow. Annotations should explain, not just label: write what is happening at each point and why it matters for people.