Rock Density from Gravity Satellite to Laboratory Data, Study Case: Lamongan Volcanic Field, East java, Indonesia
Sintia Windhi Niasari (a*), Ari Setiawan (a), Puspita Dian Maghfira (b), Yuni Indriyanti (c)

a) Physics Department, Faculty of Mathematics and Natural Sciences, Universitas Gadjah Mada, Indonesia
*sintia_windhi[at]ugm.ac.id
b) Geological Engineering Department, Universitas Gadjah Mada, Indonesia

Abstract

The Lamongan volcano is located between the Semeru and the Argopuro volcanic complex in East Java, Indonsia and is classified as a dormant volcano. This means that the Lamongan volcano has possibility to erupt. Some geological and geophysical studies had been carried out in this area. Geologically, area in this volcano is covered by andesitic breccia and lava of Lamongan and Argopuro. Some studies about rocks density using satellite gravity data were also have been performed. However, a relation between geological and geophysical studies about rocks density of the Lamongan lava had not been done. Here, we test our hypothesis that surface geological sampling of rocks resulted in different rocks density with geophysical model from satellite data. Laboratory measurement of rocks samples resulted in lava density around 3.4 gr/cc while geophysical modelling from gravity satellite data show lava density around 3.1 gr/cc. Andesitic breccias from laboratory and modelling also display slightly different value, i.e. around 2.7 gr/cc and around 2.6 gr/cc, respectively. We infer that the rocks densities difference can be due to high degree differentiation between surface and subsurface condition. Further research is needed to compare rock density from subsurface (well) and from model.

Keywords: rock density, gravity satellite, Lamongan volcano

Topic: Physics