Analysis of the Hypocenter-Epicenter Distribution Based on Volcanic Earthquake of Mount Agung Along January - December 2018 Using the Coupled Velocity-Hypocenter Method and Structural Deformation

Abstract

The eruption of Mount Agung in November 2017 became one of the largest eruptions in Indonesia. Therefore, after the eruption period, Mount Agung experienced an increase in activity in the year 2018. One of the challenges to warn and alert the citizen about the danger of eruptions is to monitor volcanic activity caused by volcanoes. Monitoring the level of volcanic activity can be conduted by determining the distribution of the hypocenter of the earthquake. In this study, the hypocenter distortion of the earthquake was determined using the Coupled Velocity-Hypocenter method with 2D and 3D plotting. This method produces outputs such as the hipocenter coordinates, the local 1-D velocity model of the P wave, as well as the correction of the station. This model gives the information about the structure of the Earth's layers through the seismic wave. Based on the calculations that have been [revealed], the distribution of the hippocenter is centered in the southwestern direction of the summit of Mount Agung with a depth range of 1-10 km. This location is associated to the presence of intrusion of magma that forms the dyke resulting in many points of volcanic earthquakes due to magma movement. The type of explosive Mount Agung eruption can affect the structure of Mount Agung as a result of a massive eruption. The deformation of the structures that occurred resulted in changes in the structure of the Earth's surface, which is it could affect the lava flow path that could be hazardous if there were civilian settlements. This has become one of the key factors in addition to determining the location of the earthquake source, monitoring of structural deformation also needs to be conducted.