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 Climate change weakens Walker circulation
20.10.2017 | MARUM - Zentrum für Marine Umweltwissenschaften an der Universität Bremen

nachricht Shallow soils promote savannas in South America
20.10.2017 | Senckenberg Forschungsinstitut und Naturmuseen

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Terahertz spectroscopy goes nano

20.10.2017 | Information Technology

Strange but true: Turning a material upside down can sometimes make it softer

20.10.2017 | Materials Sciences

NRL clarifies valley polarization for electronic and optoelectronic technologies

20.10.2017 | Interdisciplinary Research

VideoLinks
B2B-VideoLinks
More VideoLinks >>>