IGCSE Geography / Hazardous environments

Natural hazards: types and where they happen revision notes

Edexcel International GCSE Geography (4GE1), chapter 3: Hazardous environments, specification point 3.1a, 3.S1. Free lesson.

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A natural hazard is an event that could harm people or damage property. Hazards can be classified by what causes them, and their global patterns can be described using locations and exceptions.

What makes an event a natural hazard?

A natural hazard is a natural event that has the potential to harm people or damage their property. A hazard is a threat, so it can exist even if nobody is harmed. It becomes a disaster when it strikes people and causes great loss of life or damage. An earthquake in an empty desert is a hazard, but it is not a disaster if it harms nobody.

How natural hazards are classified

Hazards are grouped by what causes them. Tectonic hazards are caused by movement in the Earth's crust. Climatic hazards are caused by the weather. Earthquake: a sudden, violent shaking of the ground. Tectonic. Volcanic eruption: magma, ash and gas reach the surface. Tectonic. Magma is molten rock from underground. Tsunami: giant sea waves, usually set off by an earthquake under the ocean. Tectonic. Tropical cyclone: a huge spinning storm over a warm ocean, with very strong winds and heavy rain. Climatic. Drought: a long period with much less rain than normal.…

How to tell a hazard from an impact

The hazard is the natural event itself. The impact is what that event does to people or their property. Naming an impact instead of an event does not correctly identify the hazard. Ashfall, a lava flow and ground shaking are hazards. Destroyed buildings are an impact of a volcanic eruption, not the hazard itself.

Where earthquakes and volcanoes happen

Earthquakes and volcanoes are not spread evenly across the world. They occur mainly in narrow belts along plate boundaries, the edges of the giant slabs that make up the Earth's surface. The Pacific Ring of Fire runs around the edge of the Pacific Ocean and contains about 75% of the world's volcanoes. It includes the Andes on the west coast of South America and Japan on the western side of the ring. Another belt follows the Mid-Atlantic Ridge through Iceland. A second major earthquake belt crosses from the Mediterranean to the Himalaya. Hawaii is an exception: its volcanoes are…

Where tropical cyclones happen

Tropical cyclones form over warm oceans in two bands either side of the Equator. Their distribution is different from that of earthquakes and volcanoes because cyclones are weather hazards. The bands lie between about 5° and 30° north and 5° and 30° south. There are no cyclones along the Equator or within about 5° of it. The North Atlantic band includes storms heading towards the Caribbean and the south east of the USA. The north west Pacific is the busiest area, with about 25 storms a year. Cyclones also form in the Indian Ocean, north and south of the Equator. Storms move west…

Using distribution questions to gain marks

A describe question asks what the pattern is, not why it happens. A complete answer gives the overall pattern, named locations with latitudes where relevant, and an exception. For volcanoes, describe narrow belts along plate boundaries, give the Ring of Fire and the west coast of South America as examples, then mention Hawaii as an exception.