how volcanoes are form? how does it erupts? why does volcanoes are present under the ocean?

Question

kindly please give more about volcanism and what are the causes of it? What are also the effects of it to the environment, to the community,and to our climate? what are also the types of volcanism? and why is that volcanism is present in other planets as well as in the moons in the solar system? kindly send me also some useful images with regards to this volcanism?thank you

Answer 1

Volcanoes form at a weakness in the crust, usually where crust plates meet and one goes under another one (called subduction zones). The eruption happens when the pressure of the magma over powers the weight of the crust. If the pressure is allowed to build up then this can be an explosive release.

Volcanoes are very much present under water; they formed the islands of Hawaii and Iceland. They also create "hot smokers" which are underwater vents that allow hot gas to escape into the ocean; entire ecologies have developed around these vents.

According to Wikipedia: http://en.wikipedia.org/wiki/Volcanoes
"A volcano is an opening, or rupture, in a planet's surface or crust, which allows hot, molten rock, ash and gases to escape from below the surface. Volcanic activity involving the extrusion of rock tends to form mountains or features like mountains over a period of time.

Volcanoes are generally found where tectonic plates pull apart or come together. A mid-oceanic ridge, for example the Mid-Atlantic Ridge, has examples of volcanoes caused by "divergent tectonic plates" pulling apart; the Pacific Ring of Fire has examples of volcanoes caused by "convergent tectonic plates" coming together. By contrast, volcanoes are usually not created where two tectonic plates slide past one another. Volcanoes can also form where there is stretching and thinning of the Earth's crust (called "non-hotspot intraplate volcanism"), such as in the African Rift Valley, the Wells Gray-Clearwater Volcanic Field and the Rio Grande Rift in North America and the European Rhine Graben with its Eifel volcanoes.

Volcanoes can be caused by "mantle plumes". These so-called "hotspots" , for example at Hawaii, can occur far from plate boundaries. Hotspot volcanoes are also found elsewhere in the solar system, especially on rocky planets and moons."

Volcanism is a product of planets or moons with a hot molten core. Of course in the case of Titan some of those volcanoes are erupting water. Hot is a relative term and when you are out as far as Saturn is 0 degrees C (32 degrees F) is pretty warm.

A planet or moon’s core is kept molten for several reasons; from radioactive decay of heavy elements inside the core or the tidal energy from a rotating body close by. In the case of Europa it is suspected that the energy of rotating around Jupiter is enough to keep the core molten and could even provide a huge sea under kilometers of ice.

The craters on the moon were once thought to be volcanic in origin, but the core of our moon has cooled off long ago. The current craters we see on the moon are ALL due to impact by space debris; like comets or asteroids. The lunar mares or seas are a result of molten lunar crust caused by these impacts.

For pictures go here: http://images.google.com/images?gbv=2&svnum=10&hl=en&sa=X&oi=spell&resnum=0&ct=result&cd=1&q=volcanoes&spell=1
http://images.search.yahoo.com/search/images?p=volcanoes&sp=1&fr2=sp-top&ei=UTF-8&fr2=tab-web&fr=ks-ans&js=1&ei=UTF-8&SpellState=n-2761084004_q-BpK.HaokFwZbOAj8v8/haQAAAA@@
For video images go here: http://video.google.com/videosearch?gbv=2&svnum=10&hl=en&resnum=0&q=volcanoes&ie=UTF-8&sa=N&tab=iv
http://video.search.yahoo.com/search/video;_ylt=A9iby4Wt6.1GsTUAoF6JzbkF?p=volcanoes&sp=1&ei=UTF-8&fr=ks-ans&js=1&SpellState=n-2761084004_q-BpK.HaokFwZbOAj8v8%2FhaQAAAA%40%40&fr2=tab-img

Answer 2

If you had an actual question, I might be able to answer it. I aced a college-level Plate Tectonics class, but I have no idea what level of education you're at.