Introduction to Volcano.
Volcano comes from the word ‘vulcan’. The story begins after the Roman God a fire, ‘vulcan’. It was said that his rage cause fire to spew out of the Earth (eruption). In scientific definition, volcano is a vent in the Earth’s crust through which lava team and ashes are expelled. It can be either continuous or at regular intervals. It is also known as mountain or hill that have cuplike crater at the summit which form around a vent from the ash and lava expelled through it. It is also can be defined as an opening in the crust of the Earth in which molten rock called magma and gases can escape to the surface. The mountain that is formed from volcanic eruptions.
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Cc Distress of the Volcano.
Between 1900 and 1986, volcanoes have killed an average of 845 people every year. Several ways on how volcanoes can be dangerous which are;
Hot lava flows : Lava can flows faster than walking speed . Buildings, roads and trees can be destroyed by the crushing weight and burning temperature of a lava flows.
Clogging ash or toxic fumes : During an eruption, volcanoes release vast amounts of water vapour, carbon dioxide and sulphur dioxide. If we encounter pure carbon dioxide we can suffocate without air. People have been killed by poisonous and acidic gases.
Rock bombs : During explosive eruption, volcanic ash is hurled up to 45 km in the air. Several cubic kilometers of ash can rain down, covering everything in a thick layer of ash.It might look a bit like snow, but it’s rock, and very heavy. Just a few centimeter of volcanic ash is heavy enough to collapse buildings and kill crops.
10 Most Dangerous Active Volcanoes Around The World.
Yellowstone Caldera, United States of America.
It is known as a super-volcano that can wipe out the Western United States and change the course of human history. The last super volcano explosion identified occurred 640,000 years ago in Yellowstone. It does not have a cone shaped mountain, instead they form what are known as calderas.
Mount
Vesuvius in Campagnia, Italy.
It is one of the most dangerous
volcanoes because of its history of the activities.
The eruption cycle usually just
20 years and last erupted in 1944.
Popocatépetl, Mexico
Popocatépetl is
a large, glacier covered peak that lies around 35 miles from Mexico City.
The
last eruption is in 2000 and it erupted more than 20 times since 1519.
Sakurajima, Japan
Small
explosion occurred from Sakurajima’s
peak every year.
The
700,000 residents of Kagoshima, who live just miles from the volcano exposed to
a major eruption could have deadly consequences.
Galeras, Colombia
It is situated
in Southern Columbia near the border with Ecuador. It has been active
for
1 million
years and erupts frequently since 1580.
Mount Merapi, Indonesia
It can be
defined as a mountain of fire and the most active volcano in Indonesia.
It produced
more lava flow than any volcano in
the world.
Since 1548 , Mount
Merapi regularly erupted and
it have been active
for the last 10,000 years.
Mount Nyiragongo,
Democratic Republic of Congo
In the African continent, Mount Nyiragongo is one of the active volcanoes. It is well known for
its large lava lake which frequently appears in its crater.
Ulawun,
Papua New Guinea
It is located
in Papua New Guinea. Ulawun is
one of the most active volcanoes.
Eruptions from Ulawun
originate from its central crater.
Since 1700, 22 eruptions have
been recorded.
Taal Volcano, Philippines
The Taal
Volcano is a cinder cone volcano. It is located on the island of
Luzon,
Philippines where it lies at the middle of Lake Taal.
Since 1572 , the Taal volcano recorded 33 eruptions.
Mauna Loa, Hawaii
Mauna Loa is the largest volcano in the world.
It is also one
of the 5 volcanoes that makes
up the Island of Hawaii
in the middle of the Pacific Ocean.
At the past
700000 years, Mauna Loa has been erupted regularly
and the most
frequent eruption occurred in 1984.
Types of the Volcano.
Island Arc Volcano
It
occurs when two oceanic plates meet, one
of them is sub-ducted beneath the other that is drawn into the mantle. Mass of the magma is generated. Generated magma rises upward to
form island-arc volcanoes. Examples of island-arc volcanoes are Aleutians, Japan and
Indonesia.
Hotspot Volcano
It
occurs from the area in the middle of the plate where magma rises from mantle. Magma
will erupt through the plate. Eruption of magma creates a series of volcanoes. Examples : Hawaii, Galapagos,
Azores and Yellowstone.
Ocean Ridge
It occurs when
magma rises along a broad system of oceanic fissures. Fissure is
a long narrow depression in a surface. These oceanic fissures generate volcanic structure
rise out of the sea. Example of the oceanic ridge is Iceland.
Continental Margin
It occurs when there is a collision of
oceanic plate with continental plate.
Oceanic plate is sub-ducted beneath the continental plate into the mantle.
Oceanic plate
then causes the production and rise of magma.
As a
consequence, it leads to the formation of a chain of coastal mountains.
Examples of
the continental margin are Cascades and Andes.
Continental Rift
It occurs when there is a thinning of the crust.
The thinned
crust causes tectonic plates separate
a new ocean.
As a result,
magma will rise along the system of fissures.
Example of the continental rift is East African Rift
Valley.
Categories of the Volcano.
Active - It erupts frequently or recently or is likely to.
Dormant - It is temporarily inactive but not fully extinct.
Extinct - It is never likely to erupt again and no longer volcanic.
Structure Types of the Volcano.
Shield Volcano
Liquid lava
emitted from a central vent has a collapse
caldera.
Examples of the shield volcano are Kilauea, Mauna Loa, Fernandina, Karthala, Erta
Ale,
Tolbachik and Masaya.
Strato Volcano
More
viscous lava, much explosive (pyroclastic) debris, large, emitted from a
central vent.
Examples of the strato volcano are Mount Saint Helens, Mount Rainier, Pinatubo,
Mount Fuji, Mount Merapi and Galeras.
Flood and Plateau Bassalt
It is a very
liquid lava. It flows very widespread and it can be emitted from the fracture.
Example of the flood and plateau bassalt is Columbia
river plateau.
Cinder Cone
It is an explosive
liquid lava. It can be emitted from the central vent. If it is continued
long enough and may build up a shield volcano.
Examples of the cinder cone are Mount
Tabor and Mount Zion.
Caldera
It is a very
large composite volcano collapsed after an explosive period which
is frequently
associated with the plug domes.
Examples of the caldera are Crater Lake and Yellowstone.
Volcanic Dome
It is a very
viscous lava. It can be explosive and commonly occurs
adjacent to the craters of
the composite volcanoes.
Examples of the volcanic dome are Mount Saint Helens Lava Dome and Mount Lassen.
Magma and Lava.
Magma is a hot molten rock which is mixed with gases and mineral crystals
in the Earth's crust.
Lava is a magma that breaks through the Earth's surface and flows down the volcano.
It contains the molten rock expelled by the volcano during the eruption.
It is also known as the resulting rock after solidification and cooling.
There are three basic types of the magma:
1. Basaltic - It has low silica content and low viscosity of the magma.
Easily for gases to escape.
Non-explosive eruption.
2. Andestic - It has medium level of silica content.
It has intermediate viscosity of the magma.
Intermediate explosiveness.
3. Rhyolitic - It has a high silica content and high gases viscosity.
Difficult for gases to escape.
Furthermore, there are also three basic types of the lava:
1. Pillow lava
It is erupted at a mid-ocean ridges and large intraplate volcanoes. The best way to detect
the pillow lava is by finding water lying sediment between individual pillow.
Sediment is generated once the pieces of the lava fall off during the rapid collapsing.
The rapid collapsing is commonly occurred when the lava flows under the water.
The pillow lava is formed from a low effusion-rate eruptions of fluid basalt lava.
This lava tends to have the thicker skins of glass and less vesicular skin.
2. Pahoehoe
It has a smooth, billowy and ropy surface. Its flow tends to be relatively thin.
3. A'a
It has a rough and generally clinker in the surface. Its flow tends to be relatively thick.
This lava flows rapidly with higher viscosity of the lava.
Volcano Monitoring Method.
Seismicity
The seismic monitoring at
volcanoes is functioned to record and monitor
the
earthquakes and tremor that accompany volcanic unrest.
Seismographic
networks record the signals radiated from the volcanic seismic
sources,
then seismologists analyze and interpret
these signals and the
patterns.
A refers to volcanic-tectonic (VT) earthquake. It is characterized by clear wave onset.
It contains energy across a broad range of seismic of frequencies.
B refers to long-period (LP) earthquake.
It is characterized by dominant and lower frequency of oscillation.
C refers to volcanic tremor.
It is characterized by continuous or sustained ground oscillation at the restless volcano.
D refers to explosion earthquake.
The explosion normally occurred at the vent of volcano or at the shallow depth
beneath the vent.
Ground Deformation
Ground deformation is important in quantifying the characteristics of
the deformation over
the space and time which can give the vital information about
the depth, volume of change and
geometry of gamma reservoirs below the ground.
There are six instruments that have been used to quantify the ground
deformation:
1. Electronic Distance Measuring (EDM)
EDM measures the travel time of a laser
pulse between the two benchmarks.
After that, it converts the time to the
distance. Measured distances are accurate to
within a few centimeters.
2. Ground Tilt
It is a cylinder, 0.6-1.0 meter in length and filled with an electrolytic fluid
that contains a bubble. Electrodes sense the movement of the bubble as the instrument tilts.
Tiltmeter is placed in a sand-filled borehole in bedrock approximately at a depth of 2 meters.
Then, the tilt of the ground surface can be measured.
3. Triangulation
It functions as a measurement of the horizontal angles of a triangle.
The vertices are benchmarks that may be tens of kilometers distant from one another.
Any change in the angles over the time are used to determine the horizontal deformation
of the Earth's surface.
4. Global Positioning System (GPS)
GPS is the ultimate tool for measuring three-dimensional displacements.
It measures the horizontal and the vertical displacements within accuracy of
a few millimeters using the processing software from NASA.
5. Leveling
It is a method that measures the vertical elevations of benchmark.
Repeated leveling surveys along a series of benchmark can determine the elevation
changes over the time to sub-millimeter accuracy.
6. Aerial Photography/Light Detection and Ranging (LIDAR)
LIDAR uses a higher frequencies of light to survey the elevation of the ground surface.
Direct Fumarole Sampling of Gases and Isotopes
The method is suited for a long-term surveillance of volcanic systems because
it can produce and provide a detailed chemical analysis of the specific fumaroles
and vents. Volcanic gas samples are collected by inserting a chemically inert
and durable tube into a hot fumarole.
Gas samples are sent to an analytical lab for the analysis by ion and
gas chromatography.
The composition of the gas or a change in the rate of gas emission
will provide additional information on what is happening inside the volcano.
For an example, an increase in the ratio of carbon to sulphur can be used
to indicate the arrival of a new batch of magma at the summit reservoir.
Emission of Gas Plumes and Ash Clouds Monitoring
by Correlation Spectrometer (COSPEC)
COSPEC is an optical instrument with an upward-looking telescope.
It is used to measure sulphur dioxide emission rates from the volcano.
It measures the amount of ultraviolet light absorbed by sulphur dioxide molecules
within a volcanic plume using the scattered sunlight as its light source.
Video's Corner...
Volcano Quote :)
By death the moon was gathered in long ago, ah long ago,
Yet still the silver corpse must spin,
And with another's light must glow.
Her frozen mountains must forget their primal hot volcanic breath,
Doomed to revolve for ages yet,
Void amphitheatres of death.
And all about the cosmic sky,
The black that lies beyond our blue,
Dead stars innumerable lie,
And stars of red and angry hue,
Not dead but doomed to die.
Written by Sir Julian Huxley.
Special Appreciation to Our Volcano Team HPY555
Muhamad Nazmie Bin Rahmad 2012460598
Abdul Muqit Bin Abdul Waled 2012684816
Mohd Fareez Faisal Bin Saad@Asri 2012473818
Nur Syakila Binti Rohawi 2012240676
Zayan Nabilah Rasyidah Binti Abd Razak 2012256104
Nornaizie Binti Che Nordin 2012422802
Zarina Binti Sarkawi 2012267612
