Distribution of Tectonic Hazards
Geography: Edexcel A Level, topic 1.1.2
Distribution of Tectonic Hazards
The global distribution of tectonic hazards (earthquakes, volcanoes and tsunamis) can be explained by plate boundaries and other tectonic processes.
Tectonic hazards
- A hazard is a natural/geophysical event that has the potential to threaten both life and property.
- Hazards happen at either divergent plate boundaries, convergent plate boundaries or conservative plate boundaries.
- The distribution of hazards is uneven – some areas of the world are at high risk and others are at low risk.
Distribution of plate boundaries
- Tectonic hazards (volcanoes, earthquakes, tsunamis) happen at specific points that are usually associated with tectonic plate margins.
- Earthquakes also happen where the Indo-Australian plate collides with the Eurasian plate – a collision zone.
Causes of Intra-Plate Earthquakes and Volcanoes
Earthquakes and volcanoes can happen in the interior of tectonic plates, as well as at plate boundaries. Mantle plumes create areas of weakness known as hotspots and result in volcanoes.
Hotspots
- At hotspots, there is a hot mass of rising heat under a weakness in a plate.
- Magma rises to the surface through this weakness.
- The Hawaiian islands all formed as a result of a mid-Pacific hotspot.
Intra-plate volcanoes
- Volcanoes can happen at hotspots (e.g. Hawaii).
- Isolated plumes of convecting heat (mantle plumes) rise towards the surface generating basaltic volcanoes.
- The plume remains stationary, although the tectonic plate above moves slowly over it.
- Continuing plate movement over time produces a chain of volcanic islands, with extinct ones furthest from the plume location.
Intra-plate earthquakes
- Earthquakes can happen in mid-plate settings, usually associated with ancient fault lines being re-activated by tectonic stresses (e.g. minor earthquakes in the UK).
- Zones of weakness are created as plates move and stresses increase.
Test yourself on Distribution of Tectonic Hazards
What is the name given to the impact of the Indo-Australian plate with the Eurasian plate?
Formation of Intra-Plate Volcanoes
How are hotspots made?
What is a cause of intra-plate earthquakes?