Geology glossary

Updated: Nov 25, 2021 06:55 GMT -

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shield volcano

Volcanology
Mauna Loa shield volcano (Big Island, Hawaii)
Mauna Loa shield volcano (Big Island, Hawaii)
Shield volcanoes are volcanoes that mainly erupt fluid (usually basaltic) lava flows that are able to travel over long distances and thus construct over time broad, gentle slopes. They are called shield volcanoes, because they resemble the shape of a warriors'shield.
Shield volcanoes are volcanoes that mainly erupt fluid (usually basaltic) lava flows that are able to travel over long distances and thus construct over time broad, gentle slopes. They are called shield volcanoes, because they resemble the shape of a warriors'shield.
While stratovolcanoes, the other major morphological type of volcanoes, are representative for most subduction-type volcanoes, sh... Read all

skylight

Volcanology
Skylight on Etna volcano (Italy)
Skylight on Etna volcano (Italy)
Skylights are openings in the roof above a lava tube, from where the flowing lava flow can be seen. Usually, these holes are caused by the simple collapse of the roof of the tube.

Related keywords (1):

Coulée de lave

smoke ring

Volcanology: volcanic smoke ring, gas ring, steam ring
Etna's Bocca Nuova crater in 2000, emitting smoke rings
Etna's Bocca Nuova crater in 2000, emitting smoke rings
A rare phenomenon, where a visible vortex ring of steam and gas is expelled from a volcanic vent.
Under special conditions, gas and steam expelled from a vent can form gas rings. It probably requires a particular geolometric configuration of a circular vent exit, as well as expulsion of gas in individual puffs with just the right velocity.
This phenomenon is quite rare, but has been witnessed at several volcanoes, including Stromboli and Etna. At Etna, a spectacular period lasting several mo... Read all

strombolian eruption

Volcanology
Strombolian eruptions from vents of Stromboli volcano, Eolian Islands, Italy
Strombolian eruptions from vents of Stromboli volcano, Eolian Islands, Italy
Strombolian eruptions are the smallest type of explosive eruptions. Strombolian eruptions consist of intermittent, generally relatively small explosions or weak pulsating fountains of fluid (usually basaltic) lava from a single vent or crater.
They are called so after the type locality of Stromboli volcano (Eolian Islands, Italy), which has been in strombolian activity for probably more than 2000 years.
An individual strombolian explosion is the result of sudden release of volcanic gasses. The typical rhythmic occurrence is caused by gradual accumulation of gas bubbles beneath a weakly solidified plug at the top of the magma column at the vent surface until the gas pressure is high enough to erupt through it, ejecting with it both solid and liquid spatter from the magma. Read all

tectonic

Earthquakes
The adjective "tectonic" refers to processes, properties, or resulting features related to the deformation (breaking and slow, plastic deformation) of rocks over large sections of the upper mantle and crust (lithosphere).
It is usually applied to large-scale features and processes, in the km scale and app. Smaller miniature tectonic processes are sometimes called micro-tectonic.

Related keywords (1):

intraplate

tectonic faultSynonym of: fault

Earthquakes
Illustration of the main types of tectonic faults (source: USGS)
Illustration of the main types of tectonic faults (source: USGS)

tephrite

Volcanology
Tephrite is an type of volcanic (extrusive) rock with low silica content, similar to basalt, but containing foid minerals (e.g. nephelinite, leucite) along with plagioclase.
The composition of tephrite is called tephritic.

tephritic

Volcanology
Tephritic refers to the mineral composition of tephrite, an type of volcanic (extrusive) rock with low silica content, similar to basalt, but containing foid minerals (e.g. nephelinite, leucite) along with plagioclase.

tremorSynonym of: volcanic tremor

Volcanology
Seismogram signal examples from volcanic earthquakes: Volcano Tectonic (VT) Low Frequency (LF), hybrid (mix of VT and LF), Very Low Frequency (VLF), and Tremor. Volcano name/date in lower left. (image: USGS)
Seismogram signal examples from volcanic earthquakes: Volcano Tectonic (VT) Low Frequency (LF), hybrid (mix of VT and LF), Very Low Frequency (VLF), and Tremor. Volcano name/date in lower left. (image: USGS)

tumulus

Volcanology
Tumulus with strange shapes, on the lava flow field of the 1614-24 eruption of Mt. Etna, Italy.
Tumulus with strange shapes, on the lava flow field of the 1614-24 eruption of Mt. Etna, Italy.
From Latin "tumulus" = "little hill", tumuli (pl.) are uplifted sections of pahoehoe lava crust caused by pressure from still fluid lava accumulating beneath the hardened crust.
Tumuli are a characteristic feature of all pahoehoe lava flow fields, such as prominent on Kilauea volcano, Hawaii, but also many other basaltic volcanoes including Etna. Read all

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