volcanoes???????

Question

i need to know a few things for this report im doing in scienc. there are a few things i cant find about volcanoes though. i need to know:

-how they erupt
-the damge they cause and
-how they affect weather.

also, if u have any websites i can go to, thanks. i need all thehelp i can get

Answer 1

Deep within the Earth it is so hot that some rocks slowly melt and become a thick flowing substance called magma. Because it is lighter than the solid rock around it, magma rises and collects in magma chambers. Eventually some of the magma pushes through vents and fissures in the Earth's surface. A volcanic eruption occurs! Magma that has erupted is called lava.

The June 1991 eruption of Mount Pinatubo was global. Slightly cooler than usual temperatures recorded worldwide and the brilliant sunsets and sunrises have been attributed to this eruption that sent fine ash and gases high into the stratosphere, forming a large volcanic cloud that drifted around the world. The sulfur dioxide (SO2) in this cloud -- about 22 million tons -- combined with water to form droplets of sulfuric acid, blocking some of the sunlight from reaching the Earth and thereby cooling temperatures in some regions by as much as 0.5 degrees C. An eruption the size of Mount Pinatubo could affect the weather for a few years.

20th Century Volcanic Eruptions
and Their Impact

Answer 2

When rock inside the Earth becomes hot enough it melts.
This molten rock, or magma, is less dense than the surrounding
solid rock. Just as an object that is less dense than
water will float on water, the relatively low density of
the magma causes it to rise to the surface of the Earth.

If the magma contains water and dissolved gasses, when
the magma reaches the surface the water and dissolved
gasses will suddenly expand into steam and gas, causing
a violent eruption. This is like shaking a coke
can and then popping the tab.
At convergent margins (where plates are colliding), eruptions can be very explosive.In these cases volcanoes are like triple disasters ..They usually erupt after eartquakes(like in the movie dante's peak).2nd danger is from the molten, hot flaming lava and 3rd from the thick ,dense ash that fills the atmosphere(breathing which causes lung impairments and also death from choking ).for more info check out the link below
http://www1.fccj.edu/pacrews/volcanoes2.htm

Answer 3

Volcanoes are generally found where two to three tectonic plates diverge or converge. The mid-oceanic ridges, like the Mid-Atlantic Ridge, are typical examples of divergent tectonic plates where volcanoes are formed, whereas the Pacific Ring of Fire is a typical example of volcanic activity on convergent tectonic plates. Where two tectonic plates slide past one another (like the San Andreas fault) volcanic activity is generally not found.

Volcanic activity can also occur from mantle plumes, the so-called hotspots, which occur at locations far from plate boundaries; hotspot volcanoes are also found elsewhere in the solar system, especially on its rocky planets and moons. In July 2006, a new type of volcano was discovered,[1] which was called a petitspot, to accentuate the difference with volcanoes formed by mantle plumes.

You could get more information from the link below...

Answer 4

According to the now generally accepted "plate-tectonics" theory, scientists believe that the Earth's surface is broken into a number of shifting slabs or plates, which average about 50 miles in thickness. These plates move relative to one another above a hotter, deeper, more mobile zone at average rates as great as a few inches per year. Most of the world's active volcanoes are located along or near the boundaries between shifting plates and are called "plate-boundary" volcanoes. However, some active volcanoes are not associated with plate boundaries, and many of these so-called "intra-plate" volcanoes form roughly linear chains in the interior of some oceanic plates. The Hawaiian Islands provide perhaps the best example of an "intra-plate" volcanic chain, developed by the northwest-moving Pacific plate passing over an inferred "hot spot" that initiates the magma-generation and volcano formation process. The peripheral areas of the Pacific Ocean Basin, containing the boundaries of several plates, are dotted by many active volcanoes that form the so-called "Ring of Fire." The "Ring" provides excellent examples of "plate boundary" volcanoes, including Mount St. Helens.

The accompanying figure shows the boundaries of lithosphere plates that are presently active. The double lines indicate zones of spreading from which plates are moving apart. The lines with barbs show zones of underthrusting (subduction), where one plate is sliding beneath another. The barbs on the lines indicate the overriding plate. The single line defines a strike-slip fault along which plates are sliding horizontally past one another. The stippled areas indicate a part of a continent, exclusive of that along a plate boundary, which is undergoing active extensional, compressional, or strike-slip faulting.


There are two things to think about. The first is how the weather near an erupting volcano is being affected. The second is how large eruptions will affect the weather/climate around the world. I think more people are worried about the second issue than the first.

As far as I know, the main effect on weather right near a volcano is that there is often a lot of rain, lightning, and thunder during an eruption. This is because all the ash particles that are thrown up into the atmosphere are good at attracting/collecting water droplets. We don't quite know how the lightning is caused but it probably involves the particles moving through the air and separating positively and negatively charged particles.

Another problem that we are having here in Hawai'i involves the formation of vog, or volcanic fog. The ongoing eruption is very quiet, with lava flowing through lava tubes and then into the ocean. Up at the vent is an almost constant plume of volcanic fume that contains a lot of sulfur dioxide. This SO2 combines with water in the atmosphere to form sulfuric acid droplets that get carried in the trade winds around to the leeward side of the Big Island. The air quality there has been really poor since the eruption started in 1983 and they are getting pretty tired of it.

As for the world-wide affects of volcanic eruptions this only happens when there are large explosive eruptions that throw material into the stratosphere. If it only gets into the troposphere it gets flushed out by rain. The effects on the climate haven't been completely figured out. It seems to depend on the size of the particles (again mostly droplets of sulfuric acid). If they are big then they let sunlight in but don't let heat radiated from the Earth's surface out, and the net result is a warmer Earth (the famous Greenhouse effect). If the particles are smaller than about 2 microns then they block some of the incoming energy from the Sun and the Earth cools off a little. That seems to have been the effect of the Pinatubo eruption where about a 1/2 degree of cooling was noticed around the world. Of course that doesn't just mean that things are cooler, but there are all kinds of effects on the wind circulation and where storms occur. Some folks think that large eruptions can cause the weather phenomena called "El Nino" to start. This is a huge disruption of the Earth's atmospheric circulation. The connection hasn't been accepted by everybody though.

An even more controversial connection involves whether or not volcanic activity on the East Pacific Rise (a mid-ocean spreading center) can cause warmer water at the surface of the East Pacific, and in that way generate an El Nino. Dr. Dan Walker here at the University of Hawai'i has noticed a strong correlation between seismic activity on the East Pacific Rise (which he presumes indicates an eruption) and El Nino cycles over the past ~25 years.

There are many hazards from volcanic eruptions. The different kinds of hazards can be lava flows, pyroclastic fall deposits, volcanic gases, tsunamis, and many more (Chester 193). Lava flows have killed a relatively small number of people. The majority of the damage to society from volcanoes is economic, agricultural, and settlements can be ruined (Chester 186). The damages can be increased with the change of human population is certain areas. The more people that live in hazardous areas, the higher the risk is.

A way to limit the hazards is the prediction of eruptions. There are two options for predicting volcanic activity: general prediction and specific prediction. General prediction is the study of past volcanic activity that can predict the frequency, magnitude, and style of eruptions (Chester 196). Specific prediction focuses on predicting the actual time of eruptions. This time is found based on surveillance of the volcano and monitoring its changes (Chester 194). The success of prediction depends on a lot of time and money that puts more advanced nations ahead of the poorer countries.

Many people believe that there is action that should be taken on an international level to improve the monitoring of volcanoes. They propose that we use satellites to keep an eye on the shape of volcanoes. Mass production of seismographs, tiltmeters, and gas detectors would observe seismic activity, ground deformation, and gas emission (Chester 192). These advancements would possibly help to figure out how volcanic plumbing works. Scientists also suggest that we test climatic change and study ice cores to find emissions from past eruptions (Chester 192). All of these options would help us maintain a low risk factor for future eruptions.

Answer 5

How they erupt- pressure builds up inside of the cone of the volcano.
The damage they cause-they interrupt the ecosystem by spouting toxic gases into the atmosphere.

Answer 6

try this link
http://encarta.msn.com/encnet/refpages/search.aspx?q=volcanoes&Submit2=Go