Get our newsletter!
: "One of the most eye-catching guides to the world’s volcanoes ever published.
: Our professional team of volcanologists and photographers offers unique travel opportunities: volcano expeditions, photo tours, and relaxed walking & study tours.
The Volcano Adventure Guide
: Excellent information and background for anyone wishing to visit active volcanoes safely and enjoyably. The book presents guidelines to visiting 42 different volcanoes around the world.
: spaces available / : guaranteed / : few spaces left / : booked out
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
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 generating enormous eruption columns, although basaltic lava fountains and fissure eruptions, however, still can be hundreds of meters tall. Basaltic lava is erupted at temperatures between 1100 to 1250°C.
Basalt is by far the most common volcanic rock type. Basaltic magma is formed by partial melting of material from the upper mantle, and and is therefore typical for volcanism at hot-spots and at rift-zones. In these areas, upwelling of the mantle (either caused by a rising mantle plume underneath hot-spots, or by a divergent plate boundary at mid-ocean rift zones) decreases the pressure of the hot rock and therefore causes (partial) melting.
Oceanic crust and submarine volcanoes consist largely of basalt, because most of them are formed at rift-zones (all ocean floor) or hot-spots. Among subaerial volcanoes, basaltic lava is primarily found at shield volcanoes.
Basaltic lava flows can be subdivided into two end-member structural types, according to their flow surfaces:
-- Pahoehoe lava - smooth, billowy, or ropy surface.
-- A'a' lava - fragmented, rough, sometimes spiny, or blocky surface
More on VolcanoDiscovery:
Volcano Special Tours
: We organize tours to particularly active volcanoes and during ongoing eruptions for extended observation time from various viewpoints. These trips, exclusively for very small groups, are often announced only at short notice and require fast travel and flexibility. Each trip is accompanied by a volcanologist from our team. Examples include: Kilauea (Hawai'i), Colima (Mexico), Krakatau and many others.
Tropical rainforest, coconut palm beaches, primitive culture and moon-like landscapes, and some of the world's most active and exciting volcanoes
. Join us on our expedition to Vanuatu
Volcano & eruption special tours
: Tours dedicated to usually a single volcano currently in eruption. These trip, sometimes offered only last-minute through our newsletter, are among the most adventurous and most popular in our program.
Photos from Germany
: Germany has a large number of volcanoes - most of them extinct, but the Eifel volcanic field is still potentially active.