Characterization of Volcanic Ash from the 2017 Agung Eruption, Bali, Indonesia

Abstract

In 2017, Mount Agung in Bali, Indonesia erupted after 54 years of dormancy. This eruption produced large amount of ash causing disruptions in this major tourist destination. Scientifically, however, this eruption produced important research material (volcanic ash). In this study, volcanic ash samples from 2017 Mount Agung eruption is subjected to geochemical and magnetic analyses, to gather information regarding the magmatic processes beneath Mount Agung. Samples were collected from four locations of varying distances. Magnetic analyses include measurement of magnetic susceptibility and hysteresis parameters, while geochemical analyses were carried out to determine the composition of major elements. These analyses are supplemented by petrographic analyses. Preliminary results show that the magnetic susceptibility values of the samples vary from 778 to 1002 × 10-8 m3/kg, the grain type is non-SP until the SP and non-SP grain mixtured, and the magnetic domain is the PSD and SP which differ significantly different from that of volcanic ash samples from other volcanos (Kelud, Sinabung, Soputan, Bromo, Merapi, Slamet) reported by previous studies. The results signify the potential use of rock magnetic methods combined with geochemical and petrographic analyses in characterizing volcanic ash.