Following an aerial inspection over Mt. Kanlaon on board two Black Hawk helicopters of the Philippine Air Force, state volcanologists warned that a “hazardous eruption” may occur on Negros Island in the coming weeks. True enough, it finally happened.
The Philippine Institute of Volcanology & Seismology has said that Alert Level 3 remains in effect over Kanlaon, which means that a “hazardous eruption” is possible.
“We are not discounting that possibility that it may happen, and Alert Level 4 may be raised,” said Phivolcs Director Teresito Bacolcol during a meeting of the Provincial Disaster Risk-Reduction & Management Council in Canlaon City.
Studies have established that a volcanic eruption is an eruption of molten rock, hot rock fragments, and hot gases emitted through a volcano, which is a vent on a planet’s or satellite’s crust.
Volcanic eruptions can cause disastrous loss of life and property. They range from relatively-gentle eruptions, to massively- destructive ones, such as the eruption of Mt. Vesuvius (1,281 meters above sea level) in Italy that destroyed Roman settlements like Pompeii in the year 79 A.D. It has erupted many times since, with the last eruption in 1944.
Close to home, Mt. Kanlaon is the highest peak in the Visayas, with an elevation of 2,465 meters above sea level. It’s the world’s 42nd highest peak on an island.
Volcanic eruptions have captured the imagination of people over millennia, and they feature in several mythologies, as well as works of fiction.
These eruptions also play a role in climate change, with expelled gases, such as carbon dioxide, contributing to global warming; while ash, dust, and gases, such as sulfur dioxide, driving global temperatures down.
Volcanic eruptions occur as a result of heat moving under the earth’s surface. They often begin with an accumulation of gas-rich magma (molten underground rock) in reservoirs near the earth’s surface, though they may be preceded by emissions of steam and gas from small vents in the ground.
Small earthquakes, which may be caused by a rising plug of dense, viscous magma oscillating against a sheath of more permeable magma, may also signal volcanic eruptions, especially explosive ones.
In some cases, magma rises in conduits to the surface as a thin and fluid lava, either flowing out continuously or shooting straight up in glowing fountains or curtains.
In other cases, entrapped gases tear the magma into shreds, and hurl viscous clots of lava into the air.
In more violent eruptions, the magma conduit is hollowed out by an explosive blast, and solid fragments are ejected in a great cloud of ash-laden gas that rises tens of thousands of metres into the air. Many explosive eruptions are accompanied by a pyroclastic flow, a fluidized mixture of hot gas and incandescent particles that sweep down a volcano’s flanks, incinerating everything in its path.
Volcanic eruptions can also result in secondary damage, beyond the direct loss to life and property from the eruption itself.
Volcanic ash can cause respiratory illnesses such as silicosis, and can be particularly harmful to infants and people with chronic lung diseases.
Gases such as hydrogen chloride, carbon monoxide, and hydrogen fluoride can cause both short- and long-term problems.
Eruptions can cause economic harm that affects workers’ livelihoods, and can force mass migrations of people in affected regions.
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