THE MECHANISM OF THE 2010 SEMERU ACTIVITIES BASED ON VOLCANO-TECTONIC EARTHQUAKES ANALYSIS

• Main Author: KURNIA PRAJA (NIM : 30207001), NIA
• Format: Dissertations
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/29613
• Institution: Institut Teknologi Bandung

Mechanisms related to volcanic activities could be analysed by various means, including analysis of volcano-tectonic (VT) earthquakes. In 2010, Mount Semeru experienced intense activities providing ample opportunities to record its VT earthquakes. In this research, seismograms from Semeru’s VT earthquakes during 2010 were analysed to seek an understanding on a mechanical model for Semeru’s activity and a prediction on magma ascent rate. To achieve this objective, first earthquake data from five seismic stations around Semeru were sorted and only VT earthquakes were used in further processing. Hypocentres and focal mechanisms were then calculated from VT seismograms. The results were then used to calculate changes and distribution of strain and stress due to the existing fault system in the region. Together with few assumptions, all resulting data were later used to create the mechanical model of volcano activity and the prediction of magma ascent rate. The data show that there is a strong correlation between hypocentre distribution and focal mechanisms as well as stress changes. Distribution of hypocentre infers the presence of two magma chambers. The first chamber is shallower at the depth between 0.5 to 3 km below sea level while the second one is deeper at the depth 6 km below sea level. Furthermore, the ascent rate of the magma was found to be 0.005 m per second. This ascent rate determines the type of eruption which is extrusive.