Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

How volcanoes are formed

30.06.2006
Volcanoes often gather in groups, the so-called hot spots. The Hawaiian Islands are a striking example. One of the reasons for such hot spots appearance – is formation of the so-called thermochemical plume in the Earth’s mantle.

Researchers from the United Institute of Geology, Geophysics and Mineralogy (Siberian Branch, Russian Academy of Sciences) under the guidance of Academician N.L. Dobretsov have developed such object formation model. The researchers are interested how the plume would behave near the Earth’s surface and whether lava would pour out on the surface. To this end, they have built a mathematical model.

The thermochemical plume is formed at the core and mantle boundary, in the location where chemical additive is present, which lowers melting temperature at the mantle bottom. At this section, the melted rock column starts to move through the mantle and it rises until it reaches the infusible layer of lithosphere. Having set against it, the plume spreads under the infusible layer, forming a mushroom-like head. The head supported from below grows up gradually, the heat coming from the Earth’s interior fuses the lithosphere bottom, the diameter of molten section is also growing. The secondary upflow appears, which in the long run bursts open to the surface as red-hot lava.

All these processes take up rather long time and depend on multiple parameters. Russian scientists tried to take everything into account. According to their calculations, the secondary plume rises up from the depth of 100 to 200 kilometers at the rate of 1.2 – 2.4 centimeters per year, and it can burst out to the surface from the depth of about 30 kilometers. Consequently, this path takes, depending on the depth and the traverse speed, from 2.9 to 14.2 million years. Thus, contemporary eruptions have a long-standing history.

Eruption can take place only under definite conditions and depends, specifically, on heat flow rate and the plume head diameter. If the head diameter is big, then lava may burst out into the surface at a vast territory in several hot spots. According to the Novosibirsk geophysicists’ calculations, if the flow rate is 3?10^11 Wt, eruption will happen, should the head diameter be 770 to 1310 kilometers, but if the flow rate is thrice as little, diameter of the region to be covered by volcanoes soon or not that soon, would make 450 to 770 kilometers.

Determining the growth length and size of the plume head, that rose from deep mantle layers toward the lithosphere, is an important task for geodynamics, and researchers are now actively solving it. Russian geophysicists’ calculations allow to determine the plume head diameter dependence upon time and thermal power of the source, and, consequently, to characterize known upflows and to forecast eruptions several million years in advance.

Sergey Komarov | alfa
Further information:
http://www.informnauka.ru

More articles from Earth Sciences:

nachricht Turning the Climate Tide by 2020
29.06.2017 | Potsdam-Institut für Klimafolgenforschung

nachricht Predicting eruptions using satellites and math
28.06.2017 | Frontiers

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Supersensitive through quantum entanglement

28.06.2017 | Physics and Astronomy

X-ray photoelectron spectroscopy under real ambient pressure conditions

28.06.2017 | Physics and Astronomy

Mice provide insight into genetics of autism spectrum disorders

28.06.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>