A Volcano That Hasn t Erupted in a Long Time and Is Unlikely to Erupt Again Are Called
What is a Volcano?
A volcano is an opening in the Earth's crust that allows magma, ash and gasses to erupt from beneath the surface. It is fabricated up of a magma chamber, a vent, a crater and a cone shaped mountain made of layers of ash and lava.
Magma sleeping room → Magma from the World'southward mantle collects in a big underground pool. The magma in a magma chamber is under bully pressure trying to strength its style up to the surface.
Vent → The magma forces its fashion upwardly through the vent which is like a chimney for the volcano. There is the main vent but there can also be secondary vents on the side or flank of the volcano. These secondary vents produce secondary cones on the flank of the volcano.
Crater → The crater or caldera is the bowl shaped feature on top of the volcano that the magma from the vent erupts form.
Cone shaped mount → The majority of volcanoes are cone shaped mountains. They are formed of alternating layers of lava and ash from multiple eruptions. As the volcano erupts a layer of lava forms, the ash cloud formed during the eruption afterwards cools and falls, this is known as pyroclastic flow. This forms a layer of ash on top of the lava. This process is repeated each time the volcano erupts.
What is the difference between magma and lava? Magma is molten stone below the surface of the Earth'south chaff, when this molten rock reaches the surface of the earth is is then called lava.
Stages of a Volcano's life.
There are 3 types of volcano based on the different stages in the volcano's life. These are Active, Dormant and Extinct.
Active → Active volcanoes erupt regularly examples of active volcanoes are Kīlauea in Hawaii, Mount Etna in Italia and Mount Stromboli also in Italy which has been erupting virtually constantly for the last 2000 years.
Prototype
Dormant → Fallow volcanoes are volcanoes that have not erupted in a long time but are expected to erupt again in the time to come. Examples of fallow volcanoes are Mount Kilimanjaro, Tanzania, Africa and Mountain Fuji in Nippon.
IMAGE
Extinct → Extinct volcanoes are those which accept not erupted in human history. Examples of extinct volcanoes are Mount Thielsen in Oregon in the US and Mount Slemish in Co. Antrim.
Where practice Volcanoes occur?
The majority of volcanoes occur at plate boundaries. They can occur where plates separate, an example of this is Iceland. Here volcanoes are formed past the North American and Eurasian plates pulling apart. (come across divergent plate boundaries)
They tin also occur where plates collide. Mountain Etna is formed past the subduction of the African plate under the Eurasian plate. The melting of the subducted plate causes an increment in pressure level which leads to the germination of a magma sleeping room and in turn a volcano.
Image credit: National Geographic
Volcanoes can also form at areas known as Hot-Spots. Hotspots are caused by magma of increased temperature from a drape plume. This hot magma melts through the rock of the World'due south crust and rises through the cracks to form a volcano.
452 of the world'due south volcanoes can be institute in what is known as the Pacific Ring of Fire. this is an area of intense volcanic activeness due to plate tectonics. 75% of the earth agile and dormant volcanoes can be institute here.
What causes volcanoes to erupt?
Stone from subducted plates melts to form molten magma which pushes its way towards the surface forming a magma chamber. Gasses that accept been dissolved in the magma expand causing a massive increase in pressure level. This increment in pressure causes the magma to rise and force its way through cracks/fissures in the volcano above. As it reaches the surface the pressure level is released and an eruption occurs. During an eruption volcanic ash, stone particles, grit, gasses and lava are all ejected.
How fierce the eruption is depends on the corporeality of silica present in the magma. Silica produces a thicker magma that is better at trapping gasses. The more than gas present the greater the pressure. Therefore the more silica present in the magma the more than vehement the eruption will be.
Types of lava and their consequence on the volcano structure
At that place are two types of lava, acidic and basic.
Acidic lava has a high silica content and this makes it thicker. This thick lava doesn't travel far and due to the high level of dissolved gas it has tearing eruptions. Combined these cause the volcano to have a steep sided cone. These are known every bit Cone Volcanoes.
Basic lava contains less silica, this allows the gasses to escape and gives a runny lava. Eruptions of this blazon of lava a gentler and this forth with it being runny allows the lava to flow farther. Volcanoes of this blazon of lava will take gently sloping sides. They are known as Shield volcanoes.
For more information on the types and shapes of volcanoes see Tulane Academy website
How tin can we forecast volcanic activity?
By studying the type of materials and distribution of deposits geologists can learn a lot about the activity of volcanoes.
Eruptions tin be predicted in a number of ways:
Tiltmeters are very sensitive devices that are used to identify whatever jutting of the sides of a volcano. Increased pressure level that causes the volcano'due south sides to bulge out indicating an eruption may be about to happen.
Gases or steam coming out of vents in the volcano or the appearance of geysers could propose an eruption will soon follow.
Seismometers are used to find vibrations in the rock. These could exist caused past the movement of the magma or the groovy of rocks due to increased hea both of these would indicate an eruption being imminent.
For real time monitinrg of the worlds volcanoes see the World Arrangement of Volcanic Observatories website
Ireland and Volcanoes
Republic of ireland is not known for its loftier level volcanic activity in recent history but by studying the landscape volcanoes from hundreds of millions of years ago tin can be still exist seen.
There are a number of extinct volcanoes in Ireland these include Slieve Gullion in County Armagh, Croghan Hill in County Offaly, Mount Slemish in County Antrim, Lambay Island in Dublin and Loch Na Fooey in County Galway. These volcanoes are all extinct with the terminal eruption was approximately 60 one thousand thousand years ago.
Today the Geological Survey continues to identify previously undiscovered volcanoes hidden below the surface of Ireland. To learn more about these Geophysical surveys visit the Tellus page.
Other volcanic activity can likewise be identified here in Republic of ireland. I of the world'southward most famous Geoheritage sites The Behemothic's Causeway, is a event of volcanic activity. Approximately sixty million years ago Antrim was at the heart of intense volcanic action, magma from below the Earth's surface forced its way upward through fissures in the rock and formed a huge lava plateau. Every bit this lava rapidly cooled it contracted forming the famous hexagonal columns.
To learn more on the Giant's causeway website.
Image credit: Republic of ireland.com
Source: https://www.gsi.ie/en-ie/geoscience-topics/natural-hazards/Pages/Volcanoes.aspx
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