Tectonic Hazards

Key terminology

Subduction – the process of a plate being pushed beneath another. This is primarily due to slab pull and ridge push.

Friction – the resistance between the plates in the lithosphere.

Pressure – a force exerted on a given area, e.g. the force of gasses within a volcano pushing against the solid rock.

Magma – hot molten rock under the Earth’s surface.

Plate boundary – the place where two tectonic plates meet.

Epicentre – the point on the Earth’s surface vertically above the precise location of where an earthquake starts.

Focus – the point underground where rocks start to fracture to cause an earthquake. 

Pyroclastic flow – a fast moving, super-heated cloud ejected from some volcanic eruptions.

Ash – fragments of minerals, glass, and rock particles ejected during a volcanic eruption.

Population density – the amount of people per 1km2.

Seismic waves – shock waves that emanate from the focus of an earthquake. There are different types of waves. For example, P-waves and S-waves travel through the Earth whilst Surface waves remain on the surface, are slower and, with their have larger amplitudes, do the most damage to surface structures.

Ground deformation – the change in shape of the surface of the Earth resulting either from tectonic movements of the Earth’s solid surface or movements of magma beneath it. 

Seismometers – tools which detect, record and measures seismic waves. 

Tsunami – a series of ocean waves which can send surges of water onto the coastline. These surges can be over 30 meters high and can create a lot of damage in the process.