Physical modeling of magma chamber of slamet volcano by means of satellite gravimetric data

Abstract

Slamet Volcano (3, 432 m) is the highest volcano in Central Java, Indonesia with a weak explosive type of eruption compared to other active volcanoes. Physical modeling of magma chamber is very important because it can help to reveal the characteristics of Slamet Volcano eruptions. The modelling used the gravimetric satellite data from GGMplus, which is best in spatial resolution compared to other satellite data, i.e. 220 m . Data processing began with Bouguer correction and terrain correction and resulted in complete Bouguer anomalies data with the values ranging from 11.068 to 117.451 mGal. Further, residual Bouguer anomalies data were obtained after data reduction to the horizontal surface and removal of regional anomalies data to obtain values ranging from -67.569 to 38.808 mGal. The residual anomaly contour map showed the lowest anomalous value under the volcanic cone at positions of 109.21967° E and 7.24281° S as estimated to be the location of the magma chamber of Slamet Volcano. However, the inversion modeling resulting from the residual Bouguer anomalies data showed that the magma chamber of Slamet Volcano can be observed clearly at the positions of 109.22053° E and 7.24719° S. The location of the magma chamber is not perfectly vertical under the volcanic cone but has a slight slope. The obtained model of the magma chamber has a relatively small volum e and shallow depth, i.e. about 1 – 4 km. The obtained physical parameters of the magma chamber impact the characteristics of the eruption of Slamet Volcano, which tends to be weak explosive.