Related topics: volcano

A volcanic eruption in 2020 led to hours-long thunderstorm

A study conducted by scientists at the U.S. Geological Survey, the National Oceanic and Atmospheric Administration, and Vaisala Inc., published yesterday in the Geological Society of America's journal Geology, discusses how ...

EXPLAINER: Why Tonga eruption was so big and what's next

People around the world looked on in awe at the spectacular satellite images of an undersea volcano erupting in a giant mushroom cloud in the Pacific. Many wondered why the blast was so big, how the resulting tsunami traveled ...

Huge Tonga volcanic eruption caused 'significant damage'

A massive volcanic eruption in Tonga that triggered tsunami waves around the Pacific caused "significant damage" to the island nation's capital and smothered it in dust, but the full extent was unclear with communications ...

One of the oldest human fossils just got older: study

One of the oldest known Homo sapiens fossils may be more than 35,000 years older than previously thought, according to a study on Wednesday that used volcanic ash to date the find.

Volcanic ash halts flights on Spanish island

Planes were grounded on La Palma, one of Spain's Canary Islands, for the second straight day Sunday because of ash from a volcano that began erupting a month ago.

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Volcanic ash

Volcanic ash consists of small tephra, which are bits of pulverized rock and glass created by volcanic eruptions, less than 2 millimetres (0.079 in) in diameter. There are three mechanisms of volcanic ash formation: gas release under decompression causing magmatic eruptions; thermal contraction from chilling on contact with water causing phreatomagmatic eruptions and ejection of entrained particles during steam eruptions causing phreatic eruptions. The violent nature of volcanic eruptions involving steam results in the magma and solid rock surrounding the vent being torn into particles of clay to sand size. Volcanic ash can lead to breathing problems, malfunctions in machinery, and from more severe eruptions, years of global cooling.

Ash deposited on the ground after an eruption is known as ashfall deposit. Significant accumulations of ashfall can lead to the immediate destruction of most of the local ecosystem, as well the collapse of roofs on man-made structures. Over time, ashfall can lead to the creation of fertile soils. Ashfall can also become cemented together to form a solid rock called tuff. Over geologic time, the ejection of large quantities of ash can produce an ash cone.

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