VOLCANOES.DE - eZine on the subjects volcanoes, eruptions, volcanism and volcanology
Volcanoes are more than openings in the earth's crust from which lava and gases escape. Volcanoes are an important part of the creation story and of our planet's ecosystem. Volcanism dominates the face of the earth and the lives of people.
It is under these aspects that cameraman, photographer and author, Marc Szeglat, reports from the world of volcanoes and volcanic activity.
Marc also offers media professionals' videos of volcanoes and photos of volcanic eruptions. Licenses can be purchased for all photographs and video footage shown here.
FAQ about volcanoes and volcanism
What is a volcano?
A volcano is an opening in the earth's crust. Molten rock and gases that rise from the earth's mantle escape. The molten rock solidifies and accumulates in the form of lava around the opening. The result is an elevation, or a conical shaped mountain referred to as a volcano.
What takes place during a volcanic eruption?
During the ascent of magma to the surface, the principle of hydrostatic pressure relief takes place. Magma is less dense than the surrounding rock and it begins to rise like an air bubble in water. During ascent the external pressure on magma decreases and it is decompressed. Gases that till this point had been dissolved in the magma escape like the opening of a champagne bottle. Once at the surface, lava is expelled into the air by excess gas pressure and the volcano erupts.
Where does the lava come from?
Lava which is still underground and contains much gas is referred to as magma. This is primarily generated by the partial melting of silicate rocks in the earth's mantle. Magma can also form due to the melting of subducted earth crust which occurs along the plate boundaries.
How hot is lava?
Depending on the composition of the lava and the depth and the speed at which the magma rises, the temperature of lava can vary between approximately 500 ° C and 1250 ° C.
How fast can lava flow?
This is dependent on the composition of the lava, its temperature and the concentration of crystals it contains. In general, the more silicon dioxide contained in lava, the colder lava is and the more crystals and bubbles lava contains, the slower the lava. It can become so tough that it no longer flows, and become lodged in the crater (doming) like a brittle cork. At the other extreme are low-viscosity, hot lava flows (pahoehoe lava on Hawaii) that can reach speeds of 100 km / h on steep slopes.
Where are most volcanoes located?
Most volcanoes form along the continental seams and along the plate boundaries around the Pacific Ocean. This region is therefore referred to as the "Ring of Fire". Many volcanoes extend along divergent plate boundaries such as the mid-ocean ridges. Volcanoes also occur along continental fault zones such as the East African Rift Valley. There are also "hot spot" volcanoes such as Hawaii and Yellowstone which are formed by mantle plumes that rise from the core-mantle boundary.
How likely is the eruption of a supervolcano such as Yellowstone?
In the media, the term "supervolcano" is often used and associated with an imminent eruption of the Yellowstone volcano. It is true that a volcanic eruption in the Yellowstone Caldera is statistically overdue and that magma is moving in the caldera underground which leads to the swelling of the caldera floor and the emergence of new hot springs. However, local volcanologists agree that a volcanic eruption is not imminent.
Created by: Marc Szeglat • Dülmener Str. 11 • D-46117 Oberhausen