Estimation of Volume and Column Height from Pumiceous Tephra-Fall Deposits of Mt. Raung, East Java, Indonesia

Abstract

Pumiceous tephra-fall deposits observed mainly in the western flank of Mt. Raung are indicating past explosive eruption event. The volume and the eruption column height of the eruptive event is estimated using isopach and isopleth maps. These maps are constructed from seven observation points. The pumiceous tephra-fall deposits can be divided into 9 layers from bottom to top, White Pumice Fall 1-7, Yellow Pumice Fall, and Lithic-Rich Scoria Fall. These layers not separated by any soil or weathered layer indicates no significant time gap between them. Isopach and isopleth maps are generated from White Pumice Fall 6, Yellow Pumice Fall, and Lithic-Rich Scoria Fall considering the widespread distribution of these deposits. White Pumice Fall, Yellow Pumice Fall, and Lithic-Rich Scoria Fall are resulted from eruptive event with ∼25-33 km, ∼35 km, and ∼29 km column height and 1.3 km3, 0.73 km3, and 0.32 km3 volume, respectively. Total volume of 2.35 km3 and the column height of 25-35 km suggest that Plinian eruption type of VEI 5 magnitude produces this pumiceous tephra-fall deposit sequence.