Check out our destinations and tours!
Follow us:

Support us?


Maintaining the volcano and earthquake news sections on this website, the free Volcano Webcams tool and interactive map widget is a free-time, both time- and server cost intensive effort.
If you find the information useful and would like to support us, and help keep it alive and improve it, please consider making a small donation. Thank you!

Illustrated Volcano Glossary

basalt

Volcanology
Basaltic columnar-jointed lava (Iceland)
Basaltic columnar-jointed lava (Iceland)
The most common type of volcanic rock, with a relatively low silica content and typically erupted at shield volcanoes.
Basalt is the usually hard and black volcanic rock formed from (liquid) balsalitc lava. Balsaltic lava contains less than about 52 percent silica (SiO2) by weight. Because of its low silica content, it has a low viscosity (resistance to flow). Therefore, basaltic lava can quickly and easily flow more than 20 km from a vent. The low viscosity typically allows volcanic gases to escape without genera... -> See whole entry

Related keywords (1):

andesite

base surge

Volcanology
Base surge deposits from the great Minoan eruption on Santorini (ca. 1613 BC)
Base surge deposits from the great Minoan eruption on Santorini (ca. 1613 BC)
Base surges are ground hugging, fast outward moving and turbulent, dilute clouds of gas and ash. They result from water magma interactions (violent steam explosions). During the 1965 eruption of Taal volcano (Philippines), such base surges were first observed. Some of them traveled 4 km and killed 189 people. Base surges were first identified during ocean nuclear weapons explosions in the Pacific.... -> See whole entry

Related keywords (1):

pyroclastic flow

block

Volcanology: (volcanic) block
Large ballistically ejected block on Santorini (Greece)
Large ballistically ejected block on Santorini (Greece)
Volcanic blocks are solidified rock fragments greater than 64 mm in diameter. Blocks commonly are ejected during explosive eruptions and consist of older pieces of the volcano's edifice, e.g. parts of the conduit, lava domes or older lava flows.
During violent eruptions, blocks of up to several meter size can be thrown to several km distance. For example, during the Minoan eruption (ca. 1613 BC) of the Santorini volcano in Greece, meter-sized blocks were thrown to up to 7 km horizontal distance and impacted violently into the ground, some of them destroying houses of ancient settlements. The time some of these blocks spent on their trajec... -> See whole entry

Related keywords (1):

bomb

bomb

Volcanology: volcanic bomb
Large bomb ejected from Etna volcano's SE crater.
Large bomb ejected from Etna volcano's SE crater.
Ejected fragments of fresh magma larger than 64 mm in diameter, often shaped aerodynamically during their flight.
Volcanic bombs are lava fragments larger than 64 mm in diameter that were ejected while still viscous and partially molten. Many bombs acquire rounded aerodynamic shapes during their travel through the air. Volcanic bombs include breadcrust bombs, ribbon bombs, spindle bombs (with twisted ends), spheroidal bombs, and "cow-dung" bombs. -> See whole entry

Related keywords (3):

block - breadcrust bomb - explosive

breadcrust bomb

Volcanology
Breadcrust bomb, ca. 50 cm long, from Lokon volcano (N-Sulawesi, Indonesia)
Breadcrust bomb, ca. 50 cm long, from Lokon volcano (N-Sulawesi, Indonesia)
Perfectly shaped breadcrust bomb from Nea Kameni, Santorini (Greece)
Perfectly shaped breadcrust bomb from Nea Kameni, Santorini (Greece)
Volcanic bomb with a cracked surface, similar to bread, caused by the slow expansion of the interior gas bubbles while cooling.
A breadcrust bomb is a volcanic bomb with a cracked and checkered surface, sometimes resembling the surface of a loaf of bread. The cracks develop when the outer surface of a partially molten lava fragment cools to form a brittle surface and then subsequently cracks as the hot interior expands due to the continued growth of gas bubbles. -> See whole entry

Related keywords (1):

bomb

More on VolcanoDiscovery:

Comments:

Copyrights: VolcanoDiscovery.
Use of material: Text and images on this webpage are copyrighted. Further reproduction and use without authorization is not consented. If you need licensing rights for photographs, for example for publications and commercial use, please contact us.