Topic 2 of 3Pearson EdExcel

Hazardous Environments

Earthquakes, volcanoes, and tropical storms

Tectonic plates move due to convection currents in the mantle.

Plate boundaries:

Constructive (divergent): Plates move apart. Magma rises. Volcanoes and mid-ocean ridges (e.g. Iceland).

Destructive (convergent): Plates collide. Subduction creates deep trenches, volcanoes, and earthquakes.

Conservative (transform): Plates slide past each other. Earthquakes (no volcanoes). San Andreas Fault.

Earthquakes: Caused by sudden movement at plate boundaries.

Focus = point underground where earthquake starts

Epicentre = point on surface directly above focus

Seismic waves = vibrations that travel through earth

Measured by Richter scale (logarithmic)

Tropical storms (hurricanes/cyclones/typhoons):

Form over warm oceans (>27°C) in tropical areas

Require Coriolis effect (so not at equator)

Structure: eye (calm), eyewall (most intense), spiral rain bands

Effects: strong winds, storm surges, flooding

Managing hazards: Prediction, protection, preparedness. LEDCs typically more vulnerable than MEDCs.

Key Points to Remember

1Constructive: plates apart; Destructive: plates collide; Conservative: slide past
2Earthquake: focus underground, epicentre on surface above
3Tropical storms: form over warm (27°C+) tropical oceans
4Prediction + protection + preparedness reduce hazard impact

Pakistan Example

The 2005 Kashmir Earthquake — Tectonic Hazards in Pakistan

The 2005 Kashmir earthquake (magnitude 7.6) killed 87,000 people and was caused by the collision of the Indian and Eurasian plates at a destructive boundary — the same boundary building the Himalayas. Its focus was only 26 km deep, creating devastating seismic waves. Poor building standards in remote mountain villages maximised casualties. Pakistan now has improved early warning systems, but preparedness in rural areas remains limited — a case study in hazard geography.

Quick Revision Infographic

Geography — Quick Revision