 This lapilli was erupted by Pu`u Pua`i (gushing hill) from the summit of Kilauea Volcano in 1959 and fell to the ground about 800 m downwind. See summary of this spectacular eruption . |
Lapilli
Rock fragments between 2 and 64 mm (0.08-2.5 in) in diameter that were ejected from a volcano during an explosive eruption are called lapilli. Lapilli (singular: lapillus) means "little stones" in Italian. Lapilli may consist of many different types of tephra, including scoria, pumice, and reticulite. Rounded tephra particles in this size range are called accretionary lapilli if they consist of tiny ash grains stuck together. Ash sometimes form such rounded particles in an eruption column or cloud, owing to moisture or electrostatic forces. |
 These accretionary lapilli on the surface of the Ka`u Desert south of Kilauea caldera. The lapilli formed during explosive eruptions of Kilauea in 1790 A.D.  Layer of tephra consisting of accretionary lapilli surrounded by wind-deposited ash in the Ka`u Desert, Kilauea Volcano. This layer is one of several found at this location, about 10 km from Kilauea's summit caldera. |
Accretionary lapilli Rounded tephra balls between 2 and 64 mm in diameter are called accretionary lapilli if they consist of tiny ash particles. Volcanic ash sometimes form such balls in an eruption column or cloud, owing to moisture or electrostatic forces. Lapilli (singular: lapillus) means "little stones" in Italian. |