Geology glossary

Updated: Jun 8, 2023 02:25 GMT - refresh

earthquake | effusive | epicenter | explosive

earthquake: Earthquakes

An earthquake (also called quake, tremor or temblor, rumbling etc) is the shaking of the surface of the earth resulting from a sudden release of energy in the Earth's interior, usually by sudden movements along fault lines. This movement releases energy that propagates as seismic waves.

The size of earthquakes is determined by the amount of energy released in this process. It can range in size between many orders of magnitude and is commonly given as a number on the logarithmic Richter scale. It ranges from so tiny that they are not felt and can be only detected by the most sensitive modern instruments (seismometers) to so strong that entire regions are shaking violently.
Read all
effusive: Volcanology: effusive (volcanic) eruption

Lava flow at Mt Etna volcano - a typical effusive eruption

Effusive means flowing out of lava as opposed to explosive eruptions.

If magma is sufficiently fluid and if it is not framented by expanding gasses when reaching the surface vent, it can erupt to form lava flows. This is called effusive eruption. The opposite of effusive is explosive, i.e. fragmentation of magma. Read all
epicenter: Earthquakes

The point on the Earth's surface vertically above the point (focus or hypocenter) in the crust where an earthquake occurs, i.e. where the seismic rupture nucleates.

Related keywords (1):
hypocenter
explosive: Volcanology: explosive (volcanic) eruption

A small explosive eruption at Mt Etna volcano

Explosive eruptions occur, when the erupting magma is ejected as fragments into the air, as opposed to effusive eruptions producing lava flows.

Explosive eruptions are called so, when the erupting magma is fragmented when exiting the conduit. The reason are expanding gasses from the magma itself or external water e.g. from an aquifer. The resulting fragments of the magma itself are called tephra, and consist in small and large pieces: Ash, lapilli and bombs are the typical products of explosive eruptions.
The reason for explosive eruptio... Read all

More on VolcanoDiscovery

Volcano Map

Map of currently active volcanoes
See which volcanoes are erupting at the moment! Probably more than you think...

El Hierro

El Hierro (Canary Islands) activity
Updates and news about the volcanic unrest at El Hierro volcano, Canary Islands

Canary Islands

14-day geo tour
The Canary islands boast spectacular scenery, wild nature, great culture and gorgeous cuisine. Get to know 4 jewels on one tour: Lanzarote, La Palma, El Hierro, and Tenerife., and discover some world-class geology with an expert!

Sakurajima crisis 2015

Volcanic crisis at Sakurajima - updates
A strong earthquake swarm and increased inflation were detected in August 2015 and triggered authorities to raise the alert level, as volcanologists think that a larger eruption could follow. News and updates on the events can be found on this page.

Germany