A mountain or hill, typically conical, having a crater or vent through which lava, rock fragments, hot vapor, and gas are or have been erupted from the earth’s crust, is how a volcano is defined by the Oxford dictionary. In the olden days, often people used to consider volcanoes as a punishment from the Gods for their sins. But now we are familiar with the concept or the scientific reason behind volcanic eruptions. Volcanoes erupt mainly because of because of density and pressure. The lower density of the magma relative to the surrounding rocks causes it to rise (like air bubbles in syrup). It will rise to the surface or to a depth that is determined by the density of the magma and the weight of the rocks above it. The gas trapped inside magma, not the magma itself, ultimately forces an eruption. The types of gases include water vapor (steam), carbon dioxide, sulfur dioxide, hydrogen sulfide (the rotten egg smell), hydrogen chloride, and other very strong acids.
The word volcano is derived from the name of a volcanic island in the Aeolian islands of Italy, Vulcano. And this name Vulcano is derived from the name of the Roman god of fire, Vulcan.
A volcano can be classified into mainly into 3 categories by their frequency of eruption:
i) active (expected to erupt or is erupting already)
ii) extinct (has had an eruption for at least 10,000 years and are unlikely to erupt again, because the volcano no longer has a magma supply)
iii) dormant (is an active volcano that is not erupting, but supposed to erupt again).
Volcanoes are extremely hazardous. The fast moving lava has the potential to destroy thousands of life forms. They can cause rain, thunder and lightning. Volcanoes can also have long-term effects on the climate, making the world cooler. Earthquakes, hot springs, fumaroles, mud pots and geysers often accompany volcanic activity. Here is a list of Top 10 most active volcanoes in the world:
10. Mauno Lao, Hawaii
Mauno Lao along with Kilauea, Mauna Kea, Hualalai and Kohala volcanoes form the Island of Hawaii in the U.S. state of Hawaiʻi in the Pacific Ocean. The Hawaiin name “Mauno Lao” means “Long Mountain”. Mauna Loa is the largest sub-aerial volcano in both mass and volume, and has historically been considered the largest volcano on Earth. It is an active volcano. According to the Hawaii Center for Volcanology, Mauna Loa has erupted 39 times since its recorded 1832 explosion. Mauna Loa has been erupting regularly for at least the past 700,000 years, with its most recent eruption occurring in March 24, 1984, to April 15, 1984.
09. Ulawun, Papua New guinea
Ulawun is a basaltic and andesitic stratovolcano located on the island of New Britain, Papua New Guinea, about 130 km southwest of Rabaul. It isone of the most active volcanoes in Papua New Guinea. The first recorded eruption of Ulawun was by William Dampier in 1700. There have been 22 recorded eruptions since the 1700s. It is the highest mountain in the Bismarck Archipelago at 7,657 ft. Due to its height, the biggest threat posed by Ulawun is a catastrophic structural collapse, which could generate an eruption that would cause devastation to 100s of square km of surrounding land. Seismic activity remained high at Ulawun Volcano in 2008. A magnitude 5.1 earthquake hit 10 km west of Ulawun volcano on 28th May 2009. On 14-15 February 2010 ash emissions from Ulawun volcano reached a height of 3.7 km and drifted 95 km.
08. Taal volcano, Philippines
Taal volcano is a complex volcano located on the island of Luzon in the Philippines. it is the second most active volcano in the Philippines with 33 historical eruptions since 1572. While most of these eruptions are confined to the intracaldera area, some eruptions devastate the entire region with its fallout. It’s estimated that around 5,000-6,000 people have been killed by eruptions at Taal. All of these eruptions are concentrated on Volcano Island, an island near the middle of Taal Lake. It was thought to be named as “a volcano inside a volcano” because many believed that the lake that circles the volcano was once a crater or mouth of a volcano. The last eruption had taken place in 1977 but it has shown signs of unrest since 1991, with strong seismic activity and ground fracturing events, as well as the formation of small mud pots and mud geysers on parts of the island.
07. Galeras, Columbia
Galeras is an Andean stratovolcano located in Southern Columbia near the border with Ecuador. Since the Spanish conquest it has been erupting frequently. Its first historical eruption was recorded on December 7, 1580. In 1978 it went dormant but again in 1988 went active. When scientists held a Decade Volcano conference in 1993 to address the dangers of Galeras, an unexpected eruption occurred, killing 6 scientists and 3 tourists. Since 2000, it has erupted almost every year, spouting out ash and lava and causing tremors in the region. It is currently the most active volcano in Colombia.
06. Mount Merapi, Indonesia
Mount Merapi is an active stratovolcano located on the border between Central java and Yogyakarta, Indonesia. Merapi could be loosely translated as ‘Mountain of Fire’. It is Indonesia’s most active volcano and since 1548 has erupted regularly. It has been active for 10,000 years. Smoke can be seen emerging from the mountaintop at least 300 days a year and several eruptions have caused fatalities. The latest explosion on November 30, 2010 resulted to a number of deaths and the evacuation of thousands of people residing near Merapi.
05. Sakurajima, Japan
Sakurajima is an active composite volcano and a former island of the same name located in Kyushu, Japan due to the lava flows of the 1914 eruption which caused the former island to be connected with the Osumi Peninsula in Japan. It is located in the Aira Caldera and was formed in an enormous eruption 22,000 years ago. Hundred cubic kilometers of pumice and ash were ejected causing the magma chamber underneath the erupting vents to collapse. The resulting caldera is over 20 km across. It is referred to as the “Vesuvius of the East” because of the dynamic volcanic activity and is erupting almost constantly. The volcanic activity still continues, dropping large amounts of volcanic ash on the surroundings.
04. Mount Nyiragongo, Democratic Republic of Congo
Mount Nyiragongo is an active stratovolcano with an elevation of 3470 m (11382 ft) in the Virunga Mountains, Democratic Republic of Congo. Located at the Democratic Republic of Congo, Mt. Nyiragongo is one of the most active volcanoes in the whole African continent. Mount Nyiragongo is mainly known for its large lava lakes, which frequently appear in its crater. It poses a huge threat to its nearby environs because nowhere in the world does a steep sided stratovolcano carry such a large lake of fluid lava. It has erupted at least 34 times since 1882. The last devastating eruption of Nyiragongo occurred on 17th January 17, 2002.At least 4,500 buildings were destroyed in Goma, leaving 120,000 people homeless, displacing most of Goma’s population of 500,000 in this eruption. This volcano is currently active, with Nyiragongo in an eruption that has been ongoing since May 2002.
03. Mount Etna, Italy
Mount Etna is an active stratovolcano on the east coast of Sicily, Italy. It is the tallest active volcano on the European continent, currently 10,922 ft high, though this varies with summit eruptions. According to Adrian room’s book Place-names of the World, the name Etna originated from the Phoenician word attuna meaning “furnace” or “chimney”. the first volcanic activity at Etna took place about half a million years ago and volcanism began to occur in the southwest of the summit then, before activity moved towards the present center 170,000 years ago. Mount Etna lies above the convergent plate margin between the African Plate and the Eurasian Plate. The most violent eruption in the history of Mount Etna occurred in March of 1669. The volcano spewed molten rock for days on end, the eruption finally stopped at the end of April of that year.
02. Yellowstone Caldera, United States of America
Yellowstone Caldera is the supervolcano and volcanic caldera located in Yellowstone National park, the United States. It is extremely dangerous because it’s an active super volcano, which means a volcano that is capable of producing a volcanic eruption with ejecta greater than 1,000 cubic kilometers which is nearly a thousand of times larger than most historic volcanic eruptions. Super-volcanic eruptions have the potential to threaten the extinction of species with its massive volcanic ash production and once this volcano erupts, it causes all other volcanoes to erupt causing massive tectonic activity. Super volcanoes can sleep for centuries or millenniums before producing incredibly massive eruptions that can drop ash across an entire continent. Unlike traditional volcanoes, super volcanoes don’t have a cone shaped mountain; instead they form what are known as calderas – the sunken areas that are left over from previous super volcano eruptions.
01. Mount Vesuvius, Italy
Mount Vesuvius is a stratovolcano, a volcano built up of alternate layers of lava and ash, located in the Gulf of Naples, Italy about 9 kilometers east of Naples and a short distance from the shore. It is one of those volcanoes which form the Campanian volcanic arc (the Campanian volcanic arc is a volcanic arc that consists of a number of active, dormant, and extinct volcanoes in the Campania region of Italy) Vesuvius consists of a large cone partially encircled by the steep rim of a summit caldera caused by the collapse of an earlier and originally much higher structure.
The 79 A.D. eruption of Vesuvius was the first volcanic eruption ever to be described in detail that led to led to the annihilation of the Roman cities of Pompeii, Herculaneum, and Stabiae. Pliny the Younger, author of the only surviving eyewitness account, described a sudden explosion followed by blankets of ash that fell on people as they tried to escape. It last erupted in 1944, but it usually has an eruption cycle of just 20 years.
Scientists have discovered that the ground in Yellowstone if 74cm higher than in was in 1923 – indicating a massive swelling underneath the park. The reservoir is filling with magma at an alarming rate. The volcano erupts with a near-clockwork cycle of every 600,000 years. The last eruption was more than 640,000 years ago.