Volcanic ash consists of fragments of pulverized rock, minerals and volcanic glass, created during volcanic eruptions, less than 2 mm (0.079 in) in diameter. The term volcanic ash is also often loosely used to refer to all explosive eruption products (correctly referred to as tephra), including particles larger than 2mm. Volcanic ash is formed during explosive volcanic eruptions when dissolved gases in magma expand and escape violently into the atmosphere. The force of the escaping gas shatters the magma and propels it into the atmosphere where it solidifies into fragments of volcanic rock and glass. Ash is also produced when magma comes into contact with water during phreatomagmatic eruptions, causing the water to explosively flash to steam leading to shattering of magma. Once in the air, ash is transported by wind up to thousands of kilometers away.
Due to its wide dispersal, ash can have a number of impacts on society, including: human and animal health; disruption to aviation; disruption to critical infrastructure (e.g. electric power supply systems, telecommunications, water and waste-water networks, transportation); primary industries (e.g. agriculture); buildings and structures.
Read more about Volcanic Ash: Formation, Dispersal, Preparedness, Mitigation and Management
Famous quotes containing the words volcanic and/or ash:
“Each of us, even the lowliest and most insignificant among us, was uprooted from his innermost existence by the almost constant volcanic upheavals visited upon our European soil and, as one of countless human beings, I can’t claim any special place for myself except that, as an Austrian, a Jew, writer, humanist and pacifist, I have always been precisely in those places where the effects of the thrusts were most violent.”
—Stefan Zweig (18811942)
“Thoth, Hermes, the stylus,
the palette, the pen, the quill endure,
though our books are a floor
of smouldering ash under our feet.”
—Hilda Doolittle (1886–1961)