Question

what changes will be made if a volcano erupts? I want it very descriptively

Answer 1

When a part of the earth's upper mantle or lower crust melts, magma forms. A volcano is essentially an opening or a vent through which this magma and the dissolved gases it contains are discharged. Although there are several factors triggering a volcanic eruption, three predominate: the buoyancy of the magma, the pressure from the exsolved gases in the magma and the injection of a new batch of magma into an already filled magma chamber. What follows is a brief description of these processes.As rock inside the earth melts, its mass remains the same while its volume increases--producing a melt that is less dense than the surrounding rock. This lighter magma then rises toward the surface by virtue of its buoyancy. If the density of the magma between the zone of its generation and the surface is less than that of the surrounding and overlying rocks, the magma reaches the surface and erupts.

Magmas of so-called andesitic and rhyolitic compositions also contain dissolved volatiles such as water, sulfur dioxide and carbon dioxide. Experiments have shown that the amount of a dissolved gas in magma (its solubility) at atmospheric pressure is zero, but rises with increasing pressure.

For example, in an andesitic magma saturated with water and six kilometers below the surface, about 5 percent of its weight is dissolved water. As this magma moves toward the surface, the solubility of the water in the magma decreases, and so the excess water separates from the magma in the form of bubbles. As the magma moves closer to the surface, more and more water exsolves from the magma, thereby increasing the gas/magma ratio in the conduit. When the volume of bubbles reaches about 75 percent, the magma disintegrates to pyroclasts (partially molten and solid fragments) and erupts explosively.

The third process that causes volcanic eruptions is an injection of new magma into a chamber that is already filled with magma of similar or different composition. This injection forces some of the magma in the chamber to move up in the conduit and erupt at the surface.

Although volcanologists are well aware of these three processes, they cannot yet predict a volcanic eruption. But they have made significant advances in forecasting volcanic eruptions. Forecasting involves probable character and time of an eruption in a monitored volcano. The character of an eruption is based on the prehistoric and historic record of the volcano in question and its volcanic products. For example, a violently erupting volcano that has produced ash fall, ash flow and volcanic mudflows (or lahars) is likely to do the same in the future.

Determining the timing of an eruption in a monitored volcano depends on measuring a number of parameters, including, but not limited to, seismic activity at the volcano (especially depth and frequency of volcanic earthquakes), ground deformations (determined using a tiltmeter and/or GPS, and satellite interferometry), and gas emissions (sampling the amount of sulfur dioxide gas emitted by correlation spectrometer, or COSPEC). An excellent example of successful forecasting occurred in 1991. Volcanologists from the U.S. Geological Survey accurately predicted the June 15 eruption of the Pinatubo Volcano in the Philippines, allowing for the timely evacuation of the Clark Air Base and saving thousands of lives.

Answer 2

THE ASH EFFECT

Ash from volcanoes can do more than darken the skies, coat highways, cover yards and ground airplanes. After an eruption, roofs on buildings may collapse and kill people if enough volcanic ash particles land on them. People can develop breathing problems, throat irritation and other respiratory issues when ash falls after a volcanic eruption.

CATASTROPHIC EFFECTS

More serious problems may occur when fires start as a result of contact with hot lava. Flowing lava can kill people, animals and plants that lie in its path. For example, the Mount St. Helens eruption of 1980 killed about 24,000 animals. As plants and animals die, famine can arrive in areas where people rely on those food supplies. Powerful volcanoes, such as Krakatoa, can cause catastrophic damage. Exploding with the power of 13,000 nuclear bombs in 1883, Krakatoa destroyed entire villages and killed over 36,000 people. The shockwave was so powerful that it destroyed most of the island and instruments detected the blast thousands of miles away.

CLIMATE CHANGE AND VOLCANIC ACTIVITY

While greenhouse gases help warm the planet, volcanoes can make it cooler. Powerful volcanoes spew hydrogen chloride, sulfur dioxide, ash and other materials high into the stratosphere. Sulfate aerosols reflect some of the sun’s energy back into space, resulting in a cooler atmosphere. These aerosols may also cause chemical reactions that produce chlorine monoxide, a substance that destroys the Earth’s ozone layer. Paradoxically, the carbon dioxide that volcanoes release can augment global warming.

THE CREATIVE SIDE OF VOLCANOES

Over 7,000 years ago Mount Mazama, an Oregon volcano, collapsed leaving Crater Lake, a major tourist attraction. Similar lakes exist in other locations around the world. Over millions of years, underwater eruptions in the Pacific Ocean caused lava to build up gradually, causing the Hawaiian Islands to form above sea level. Every island consists of at least one volcano. Volcanoes continue to help shape the ocean’s landscape. For example, an eruption south of Tokyo in 2013 created an island that could get bigger if more eruptions occur. Ash combined with other volcanic particles propelled into the atmosphere can help create brilliant sunsets around the world.

ADDITIONAL EXPLOSIVE EFFECTS

Volcanic landslides can move large amounts of dirt and rock at up to 100 kilometers per hour (62.14 miles per hour), reshaping the landscape. Acidic gases in volcanic fume clouds may rain down on the planet causing airplane surfaces, vehicles and other objects to corrode. Collapsing volcanoes and underwater eruptions can also trigger devastating tsunamis that destroy land, life and property. However, nothing lasts forever -- not even volcanoes. After they stop erupting, erosion can eventually wear them down over time to where they become hills or even valleys.