By :
Hanik Humaida and Yustinus Sulistiyo
BPPTK-Direktorat Volkanologi dan Mitigasi Bencana Geologi
Jl. Cendana 15 – Yogyakarta
Abstract
SO2 is one of the volcanic gases that can provide information about the state of volcano activity. Commonly, SO2 flux is measured by COSPEC (Correlation Spectroscopy). This equipment has several disadvantages; such as heavy, big size, expensive. DOAS (Differential Optical Absorption Spectroscopy) is a new method for SO2 gas flux monitoring that has advantages compares to the COSPEC. Recently, this method has been developed.
This DOAS consists of 5 units; namely scan miler, condenser lens, detector, power supply, and a laptop. Its total weight is up to 11 kg. For operation of DOAS using traverse method, it need only lens unit, detector and laptop. The total weight is only 2 kg. DOAS can be operated as static or traverse method and can be mounted at anyplace.
Measurement of SO2 flux by DOAS has been done at G. Bromo on 12-15 June 2004, after the 8 June eruption. Location of measurement is about 2 km from eruption source using tripod. This angle of measurement ranges between 10 and 12o, width of scan is 45o. Data was analysed by HINAGATA software. The result showed that 30 minutes prior to the ash eruption, the flux of SO2 increased from normal condition until 135 ton/day.
From : The 33rd Annual Convention & Exhibition 2004 Indonesian Association of Geologist