¨ Activity : Active
¨ Type : Shield
¨ Continent : North America
¨ Region : United States
¨ Country : United States
¨ Height : 1111 Meters
Kilauea is the world's most active volcano, it spews out 382,000 cu
m (about 500,000 cu yd) of lava a day. It is located on the southeastern
slope of the great volcanic mountain Mauna Loa, at an elevation of 1111m
(3646 ft) above sea level, more than 3000 m (almost 10,000 ft) below the
summit of the mountain. In June 1989, it had destroyed the visitor's center
at the national park, and more than 65 houses by 1990.An observatory has
been maintained on the brink of
the crater since 1911. Kilauea is part of the Hawaii Volcanoes National
Park. The vast inner pit of the Kilauea, Halemaumau, is sometimes called
"the House of Everlasting Fire".
TYPE OF PRODUCTS ERUPTED FROM THE VOLCANO
Lava Flows
Lava flows are the most common of the direct volcanic hazards in Hawaii.
They burn or bury everything they come across. They can run over houses,
roads, and any other structures.
Gas
Volcanic gas is contained within magma rises to the Earth's surface the
gases are exsolved. Because some gases are toxic they can suffocate people.
Carbon Dioxide
The gas plume rising from an active vent on Kilauea consists of about
80 percent water vapor with lesser amounts of sulfer dioxide, carbon dioxide,
and hydrogen.
Volcanic Ash
Volcanic ash is a volcanic rock which is exploded from a vent in fragments
less than 2mm in size. Volcanic ash-particles are like small sharp glass-particles
that damage anything they come across. Because volcanic ash can fall on
many things it's very harmful to the environment around the volcano.
During heavy ash-rains, houses and buildings may collapse, people and
animals may also die by lack of oxygen. Ash clouds may provide big problems
for aviations. When airplane fly through an eruption cloud, a range of
damage may occur depending on the concentration of volcanic ash, gas aerosols
in the cloud and the actions taken by the pilot to exist the eruption
cloud.
Lahars
Lahars are mudflows formed by the mixing of volcanic particles and water
which often cause a lot of environmental and economical damage. The force
of a lahar is so big that buildings and valuable land may become partially
or completely buried by one or more cement-like layers of rock debris.
Volcanic blast
Volcanic blast occurs when magma rises asymmetri-
cally into the cone, making one sector of the volcano bulge outwards and
become unstable.
Pyroclastic flows
Pyroclastic flows are mixtures of hot gas, ash and other volcanic rocks
travelling very quickly down the slopes of volcanoes. Pyroclastic flows
are so hot and choking that if one is caught in one the person will certainly
be killed. Because these flows are very fast cannot be out-runned.
Pyroclastic surges
Pyroclastic surges are low density flows of pyroclastic material. They
are more dilute, turbulent, and wide-spred in their effects than pyroclastic
flows. They contain a lot of dangerous(toxic) gases that can kill people.
Nuees Ardentes
When viscous magma, containing much gas, is erupted under reasonably low
pressure, a glowing cloud containing ash and pumice may be thrown into
the air, this cloud will fall back onto the earth like an avalanche before
it can cool off. This avalanche is called a nuees ardente.
Nuees ardentes contain mixture of gas, lava, blocks, ash and pumice. They
move very fast reaching speeds ranging to 500km an hour. The paths that
they take are influenced by gravity. Because they often strike the ground
many people are killed.
Airborne Lava Fragments
Most volcanic eruptions produce fragments of lava that are airborne for
at least a short time before being deposited on the ground. These fragments
are called "tephra," and include ash, cinders, and Pele's hair.
In Hawaii, tephra is usually ejected by lava fountains and poses a serious
hazard only in the immediate vicinity of an erupting vent.
Debris Avalanches
Debris avalanches usually occur on large, steep volcanoes like, Mt. Egmont,
and are one of the most hazardous but least common of volcanic dangers.
They are mainly caused by instability of the volcano's slope.
THE INSIDE AND THE OUTSIDE OF ACTIVE VOLCANO
A volcano constitutes a vent, a pipe, a crater, and a cone. The vent is
an opening at the Earth's surface. The pipe is a passageway in the volcano
in which the magma rises through to the surface during an eruption. The
crater is a bowl-shaped depression at the top of the volcano where volcanic
materials like, ash, lava, and other pyroclastic materials are released.
Solidified lava, ashes, and cinder form the cone. Layers of lava, alternate
with layers of ash to build the steep sided cone higher and higher.
Young Hawaiian volcano-Kilauea- can erupt either it's summit or on it's
flank. Kilauea has a summit caldera.
A caldera is a crater several miles in diameter that forms as the result
of collapse when magma drains from beneath the summit. Summit eruption
occur within or near its caldera. Flank eruption usually takes place along
rift zones.
Rift zone typically extends from the summit of a volcano toward the coastline
and may continue for many miles under the sea. Hawaiian eruptions are
characterized by lava-effusion (an eruption of lava which most commonly
gives rise to lava flows). Most frequently, they begin with lava-fountaining,
sometimes cones of fragments are formed. Utmost hot magma which has a
very low percentage of silica will flow outside the volcano in very fluid
streams. Hawaiian eruptions result in vast, gentle volcanoes known as
shields or shield volcanoes.
WHY THE VOLCANO IS OCCURING 
Volcanoes occur because the Earth's crust is broken into plates that
resemble a jigsaw puzzle. There are 16
major plates. These rigid plates float on a softer layer of rock in the
Earth's mantle. As the plates move about they push together or pull apart.
Most volcanoes occur near the edges of plates.When plates push together,
one plate slides beneath the other. This is a subduction zone. When the
plunging plate gets deep enough inside the mantle, some of the rock on
the overlying plate melts and forms magma that can move upward and erupt
at the Earth's surface. At rift zones, plates are moving apart and magma
comes to the surface and erupts. Some volcanoes occur in the middle of
plates at areas called hotspots -- places where magma melts through the
plate and erupts.
WHAT ENVIRONMENTAL AND HUMAN IMPACT DOES THE VOLCANO HAVE?
Lava flows rarely kill people, because they move slowly enough for people
to get out of their way. Lava flows, however, can cause considerable destruction
to buildings in their path. The fronts of Hawaiian lava flows generally
move more slowly than the speed at which people walk, although the lava
in the channel behind the front may be flowing much faster.
If magma is thick and sticky, gases can't escape easily. Pressure builds
up until the gases escape violently and explode. In this type of eruption,
the magma blasts into the air and breaks apart into pieces called tephra.
Tephra can range in size from tiny particles of ash to house-size boulders.
Explosive volcanic eruptions can be dangerous and deadly. They can blast
out clouds of hot tephra from the side or top of a volcano. These fiery
clouds race down mountainsides destroying almost everything in their path.
Ash erupted into the sky falls back to Earth like powdery snow, but snow
that won't melt. If thick enough, blankets of ash can suffocate plants,
animals, and humans. When hot volcanic materials mix with water from streams
or melted snow and ice, mudflows form. Mudflows have buried entire communities
located near erupting volcanoes.
Although volcanoes have the reputation of being very dangerous (Volcanoes
can kill people and animals. They can be very destructive.), there nevertheless
are advan-tages of living near a volcano. Volcanoes provide resources
for energy extraction, also called geothermal resources. Heat from the
earth's crust is being converted to energy. The big ad-vantages to this
type of energy are that it is very clean and the resources are nearly
inexhaustible. When a volcano erupts it throws out a lot of ash. At short
notice this ash can be very harmful to the environment, but on the long
term the ash layer, which contains many useful minerals, will be converted
to a very fertile soil. Nearly everywhere volcanoes are located people
use the rich soil for farming. Even after an eruption people still return
because of the fertile soil around the volcano.
Volcanoes can produce very spectacular scenery like the beautiful sunsets
caused by explosive eruptions. Other features include plant-rich environments,
stun- ning eruptions, beautiful lava fountains etc. A big economical advantage
of volcanoes is that they generate tourism. A country such as Hawaii is
getting a lot income from tourism.
REFERENCES
Internet sites
Books
National Geographic
Science Focus 7
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