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Volcanic eruptions

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Nature and flora

1980 eruption of Mount St. Helens

On May 18, 1980, a major volcanic eruption occurred at Mount St. Helens, a volcano located in Skamania County, in the State of Washington. The eruption was the most significant volcanic eruption to occur in the contiguous 48 U.S. states since the much smaller 1915 eruption of Lassen Peak in California. It has often been declared as the most disastrous volcanic eruption in U.S. history. The eruption was preceded by a two-month series of earthquakes and steam-venting episodes, caused by an injection of magma at shallow depth below the volcano that created a large bulge and a fracture system on the mountain's north slope.

Nature and flora

1883 eruption of Krakatoa

The 1883 eruption of Krakatoa (Krakatau) in the Dutch East Indies began in the afternoon of Sunday, 26 August 1883, and peaked in the late morning of Monday, 27 August when over 70% of the island and its surrounding archipelago were destroyed as it collapsed into a caldera. Additional seismic activity was reported to have continued until February 1884, though reports of seismic activity after October 1883 were later dismissed by Rogier Verbeek's investigation into the eruption. The 1883 eruption was one of the deadliest and most destructive volcanic events in recorded history. At least 36,417 deaths are attributed to the eruption and the tsunamis it created. Significant additional effects were also felt around the world in the days and weeks after the volcano's eruption.

Nature and flora

1815 eruption of Mount Tambora

The 1815 eruption of Mount Tambora was one of the most powerful in recorded history, with a Volcanic Explosivity Index (VEI) of 7. It is the most recently known VEI-7 event and the only unambiguously confirmed VEI-7 eruption since the Lake Taupo eruption in about 180 AD.

Nature and flora, Geography

Minoan eruption

The Minoan eruption of Thera, also referred to as the Thera eruption, Santorini eruption, or Late Bronze Age eruption, was a major catastrophic volcanic eruption with a Volcanic Explosivity Index (VEI) of 6 or 7 and a dense-rock equivalent (DRE) of 60 km3 (14 cu mi), Dated to the mid-second millennium BCE, the eruption was one of the largest volcanic events on Earth in recorded history. It devastated the island of Thera, including the Minoan settlement at Akrotiri and communities and agricultural areas on nearby islands and the coast of Crete with a related earthquake and tsunami.

Nature and flora

Limnic eruption

A limnic eruption, also termed a lake overturn, is a rare type of natural disaster in which dissolved carbon dioxide (CO2) suddenly erupts from deep lake waters, forming a gas cloud capable of suffocating wildlife, livestock, and humans. A limnic eruption may also cause tsunamis as the rising CO2 displaces water. Scientists believe earthquakes, volcanic activity, and other explosive events can serve as triggers for limnic eruptions. Lakes in which such activity occurs are referred to as limnically active lakes or exploding lakes. Some features of limnically active lakes include:CO2-saturated incoming water A cool lake bottom indicating an absence of direct volcanic interaction with lake waters An upper and lower thermal layer with differing CO2 saturations Proximity to areas with volcanic activity

Nature and flora

1257 Samalas eruption

The 1257 Samalas eruption was a major eruption of the Samalas volcano, next to Mount Rinjani on Lombok Island in Indonesia. The eruption left behind a large caldera next to Rinjani, with Lake Segara Anak inside it. This eruption probably had a Volcanic Explosivity Index of 7, making it one of the largest eruptions of the current Holocene epoch.

Nature and flora

2010 eruptions of Eyjafjallajökull

The 2010 eruptions of Eyjafjallajökull were volcanic events at Eyjafjallajökull in Iceland which, although relatively small for volcanic eruptions, caused enormous disruption to air travel across western and northern Europe over an initial period of six days in April 2010. Additional localised disruption continued into May 2010. The eruption was declared officially over in October 2010, when snow on the glacier did not melt. From 14–20 April, ash from the volcanic eruption covered large areas of Northern Europe. About 20 countries closed their airspace to commercial jet traffic and it affected approximately 10 million travellers.

Nature and flora

Plinian eruption

Plinian eruptions or Vesuvian eruptions are volcanic eruptions marked by their similarity to the eruption of Mount Vesuvius in 79 AD, which destroyed the ancient Roman cities of Herculaneum and Pompeii. The eruption was described in a letter written by Pliny the Younger, after the death of his uncle Pliny the Elder.

Nature and flora

Armero tragedy

The Armero tragedy was one of the major consequences of the eruption of the Nevado del Ruiz stratovolcano in Tolima, Colombia, on November 13, 1985. After 69 years of dormancy, the volcano's eruption caught nearby towns unaware, even though the government had received warnings from multiple volcanological organizations to evacuate the area after the detection of volcanic activity two months earlier.

Nature and flora

Strombolian eruption

Strombolian eruptions are relatively mild blasts with a volcanic explosivity index of about 1 to 3. They are named for the Italian volcano Stromboli. Strombolian eruptions consist of ejection of incandescent cinder, lapilli, and lava bombs, to altitudes of tens to a few hundreds of metres. The eruptions are small to medium in volume, with sporadic violence.

Nature and flora

Hatepe eruption

The Hatepe eruption, named for the Hatepe Plinian pumice tephra layer, sometimes referred to as the Taupo eruption and dated to around 180 AD, was Lake Taupo's most recent major eruption. It is considered New Zealand's largest eruption during the last 20,000 years. The eruption ejected some 120 km3 (29 cu mi), a VEI 7 eruption, of which 30 km3 (7.2 cu mi) was ejected in a few minutes. This makes it one of the most violent eruptions in the last 5000 years, comparable to the Minoan eruption in the 2nd millennium BC, the 946 eruption of Paektu Mountain and the 1815 eruption of Mount Tambora. The resulting ash turned the sky red over Rome and China.

Nature and flora

Explosive eruption

In volcanology, an explosive eruption is a volcanic eruption of the most violent type. Mount St. Helens in 1980 is an example. Such eruptions result when sufficient gas has dissolved under pressure within a viscous magma such that expelled lava violently froths into volcanic ash when pressure is suddenly lowered at the vent. Sometimes a lava plug will block the conduit to the summit, and when this occurs, eruptions are more violent. Explosive eruptions can send rocks, dust, gas and pyroclastic material up to 20 km into the atmosphere at a rate of up to 100,000 tonnes per second, traveling at several hundred meters per second. This cloud may then collapse, creating a pyroclastic flow of hot volcanic matter.

Nature and flora

Phreatic eruption

A phreatic eruption, also called a phreatic explosion, ultravulcanian eruption or steam-blast eruption, occurs when magma heats ground or surface water. The extreme temperature of the magma causes near-instantaneous evaporation to steam, resulting in an explosion of steam, water, ash, rock, and volcanic bombs. At Mount St. Helens, hundreds of steam explosions preceded a 1980 plinian eruption of the volcano. A less intense geothermal event may result in a mud volcano.

Nature and flora

2018 Volcán de Fuego eruption

The 2018 Volcán de Fuego eruption was a series of volcanic explosions and pyroclastic flows from the Volcán de Fuego in Guatemala on Sunday 3 June 2018. The eruption included lahars, pyroclastic flows, and clouds of volcanic ash, which left almost no evacuation time and caused over one hundred people confirmed killed. It was the deadliest eruption in Guatemala since 1929.