Source mechanism of volcanic tectonic events from October 2010 to December 2011 at the Sinabung volcano area

Abstract

From its first eruption at the end of August 2010, Mount Sinabung has been being seismically active. Thousands of micro earthquakes have occurred in the magma itself, in hydrothermal systems, and along nearby tectonic faults. The installation of a three-component seismometer network around the Sinabung volcano from October 2010 to December 2011 has encouraged more detailed study of the source characteristics of micro earthquakes. In this study, we conduct a focal mechanism analysis of volcanic tectonic (VT) activity during this period. This study delineates three kinds of faults around the volcano. First, a possible oblique-strike-slip fault that was “cut” by the volcano is confirmed. The fault parameters are a strike of 44.76°, a dip of 67.83° and a rake of 19.7°. Second, a normal-faulting zone associated with Kawar Lake is parametrized by a strike, dip and rake of 5.8°, 77.4°, and − 113.2°, respectively. Third, a clear hidden oblique strike-slip was found at the north-west part of the summit. The fault lineation is shown clearly by its hypocentre distribution and is parameterized by its strike of 213.15°, dip of 77.72°, and rake of − 20.04°.