<P> Volcanic ash consists of fragments of pulverized rock , minerals and volcanic glass , created during volcanic eruptions and measuring less than 2 mm ( 0.079 inches ) 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 . </P>
<P> Volcanic ash consists of fragments of pulverized rock , minerals and volcanic glass , created during volcanic eruptions and measuring less than 2 mm ( 0.079 inches ) 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 . </P>
tephra that is finer than 2 mm in diameter is called
tephra that is finer than 2 mm in diameter is called
Volcanic ash
Volcanic ash