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 A promising target in the quest for a 1-million-year-old Antarctic ice core
24.05.2018 | University of Washington

nachricht Tropical Peat Swamps: Restoration of Endangered Carbon Reservoirs
24.05.2018 | Leibniz-Zentrum für Marine Tropenforschung (ZMT)

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Powerful IT security for the car of the future – research alliance develops new approaches

The more electronics steer, accelerate and brake cars, the more important it is to protect them against cyber-attacks. That is why 15 partners from industry and academia will work together over the next three years on new approaches to IT security in self-driving cars. The joint project goes by the name Security For Connected, Autonomous Cars (SecForCARs) and has funding of €7.2 million from the German Federal Ministry of Education and Research. Infineon is leading the project.

Vehicles already offer diverse communication interfaces and more and more automated functions, such as distance and lane-keeping assist systems. At the same...

Im Focus: Molecular switch will facilitate the development of pioneering electro-optical devices

A research team led by physicists at the Technical University of Munich (TUM) has developed molecular nanoswitches that can be toggled between two structurally different states using an applied voltage. They can serve as the basis for a pioneering class of devices that could replace silicon-based components with organic molecules.

The development of new electronic technologies drives the incessant reduction of functional component sizes. In the context of an international collaborative...

Im Focus: LZH showcases laser material processing of tomorrow at the LASYS 2018

At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.

At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...

Im Focus: Self-illuminating pixels for a new display generation

There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?

At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

In focus: Climate adapted plants

25.05.2018 | Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

 
Latest News

In focus: Climate adapted plants

25.05.2018 | Event News

Flow probes from the 3D printer

25.05.2018 | Machine Engineering

Less is more? Gene switch for healthy aging found

25.05.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>