Volcanoes are openings through which lava, tephra or small rocks, and steam erupt onto the surface of the Earth. Volcanic terrain is built by the slow accumulation of erupted lava and its vent may be visible as a small bowl shaped depression at the summit of a cone or shield-shaped mountain.
The volcanic vent connects to one or more linked storage areas of molten rock called magma through a series of cracks within and beneath the volcano. This connection to fresh magma allows the volcano to erupt over and over again in the same location allowing the volcano to grow larger, until it is no longer stable.
How Do Volcanoes Erupt?
The molten rock magma after eruption is known as lava. The liquid magma forms crystals of various minerals after it cools to igneous or magmatic rock.
Magma originates miles beneath the ground and is lighter than the surrounding solid rock. It is driven towards the Earth’s surface by buoyancy and then forces its way upwards and ultimately breaking through weak areas in the Earth’s crust resulting in an eruption.
Magma can also be erupted in other ways, such as the molten rock simply pouring from the vent as fluid lava or it can shoot directly into the air as clouds of rock shards and gas.
Volcanoes can also be formed through hotspot volcanism wherein a zone of magmatic activity in the middle of a tectonic plate can push up through the crust forming a volcano. Sometimes the tectonic plates continue to build a line of volcanoes on the surface creating a volcanic chain.
What Are The Main Types Of Volcanoes?
- Cinder Cone Volcanoes
Cinder cones are made of small pieces of solid lava called cinder erupted from volcanic vents. When magma from within the Earth rises it shakes the ground resulting in a blast throwing molten rocks, ash and gas into the air.
When these rocks cool in the air they fall back to the earth breaking into small pieces of cinder that pile up around the vent. Cinder cone volcanoes can be thousand feet above the ground level.
- Composite Volcano or Stratovolcano
Stratovolcanoes are made out of repeated layers of lava flows, cinders, volcanic ash and volcanic bombs and can rise over 8,000 feet above their surroundings.
- Shield Volcanoes
Shield volcanoes are built of fluid lava flows. The lava then pours out of vents in all directions radiating out like spokes on a bicycle wheel. The overlapping lava flows make a sloping dome shape that appears like a warrior’s shield from distance.
- Lava Dome Volcanoes
Lava dome volcanoes basically contain the thick lava that flows away from the vent and accumulates as a giant pile over and around the vent.
Largest Volcanoes on the Planet Earth
The top 5 Largest Volcanoes on the Planet Earth are given below:-
- Mauna Loa Volcano in Hawaii
Mauna Loa is one of the largest volcanoes on Earth located on the south-central part of the island of Hawaii and is a part of Hawaii Volcanoes National Park. It is a shield volcano which is 4,169 meters elevation. It also shares a hot spot in the Pacific plate.
The most recent eruption of Mauna Loa volcano occurred from March 24 to April 15, 1984. The eruptions of this volcano in 1926 and 1950 destroyed several villages; however no recent eruptions of the volcano have caused any fatalities.
- Mount Fuji Volcano in Tokyo, Japan
Mount Fuji is a stratovolcano which is at 3,776 meters elevation. It is the tallest peak in Japan and lies on the Eurasia tectonic plate. The base of this volcano is about 78 miles in circumference with a diameter of around 25 to 30 miles.
This volcano has been dormant since its last eruption, in 1707, but is classified as an active volcano by geologists. The lava from its eruption is basaltic. The crater of the volcano is about 1,600 feet in diameter and has a depth of about 820 feet.
The crater is surrounded by eight peaks which are Izudake, Oshaidake, Komagatake, Jojudake, Kengamine, Mushimatake, Hukusandake, and Kusushidake.
- Mayon Volcano in Albay, Philippines
Mayon Volcano has steep slopes forming a symmetrical classic volcano and it is an active stratovolcano in the Philippines. It is at 2462 meters elevation, located on a convergent boundary between the Eurasian and Philippine plate.
The lava from Mayon Volcano is pyroclastic and it erupts very frequently. It is the most iconic of all the volcanoes in the Philippines because of its perfect cone shape.
The Mayon Volcano tours have become the main activity of travelers visiting the region because of its majestic view. With its record of approximately 50 eruptions in the past decades it is considered to be the most active volcano in the Philippines.
- Mount St. Helens Volcano in Washington, USA
Mount St. Helens is at 2,550 meters elevation and is an active stratovolcano located in Skamania County, Washington. It is a part of the Cascade Mountain range and it consists of lava rock inter layered with ash, pumice, and other deposits such as layers of basalt and andesite.
Mount St. Helens had the shape of a conical, youthful volcano but during the 1980 eruption the upper 400mof the summit was removed by a huge debris avalanche, leaving a horseshoe-shaped crater which is now partially filled by a lava dome and a glacier. It is categorized as an explosive dacite volcano with a complex magmatic system.
- Popocatépetl Volcano in Mexico
Popocatépetl is an active stratovolcano in Mexico and is 5,426 meters elevation. It is on the North American plate consisting of andesite magma inside the volcano.
Since January 2005 the eruption of this volcano has been observed and it consisted of lava dome growth and destruction, explosions, and emissions of ash plumes.
Since July 2020 certain activities were observed, like low-intensity emissions which included gas-and-steam and small amounts of ash, and other minor and moderate explosions sent ash plumes more than 1 km above the crater.
