PENGARUH PERUBAHAN STRESS AKIBAT GEMPABUMI DI SELATAN PULAU JAWA TERHADAP PENINGKATAN AKTIVITAS VULKANIK DAN ERUPSI GUNUNG MERAPI PERIODE MARET 2014; THE INFLUENCE OF STRESS CHANGES CAUSE BY SOUTH JAVA EARTHQUAKES TO THE VOLCANIC ACTIVITY AND ERUPTION OF MERAPI VOLCANOES IN MARCH, 2014
Hermawan, Heru Bagus, Wiwit Suryanto
2015 | Disertasi | FMIPAThe analysis of stress changes due to the earthquakes in South Java in order to determine the effect of the increasing in volcanic activity and the eruption of Mt. Merapi in March 2014 period has been done. The aim of this study is to determine the changes of both static and dynamic stress around the Mt. Merapi at depths that correspond to the existence of magma chamber. The data used for this study such as the report of activity of Merapi period March 2014 released by the Center for Research and Development of Geological Disaster Technology (BPPTKG), seismicity catalogs that have occurred since January 2014 to March 2014 were obtained from the Meteorology, Climatology and Geophysics (BMKG), seismogram of tectonic and volcanic activity in the area around Merapi obtained from seismic stations belonging to the University of Gadjah Mada (UGM) that is located in Kaliurang, the tectonic earthquake focal mechanisms data obtained from web page’s GeoForschungsZentrum (GFZ) and the Global Centroid Moment Tensor (GCMT ) and earth velocity model AK135-F obtained from the web pages of Incorporated Research Institutions for Seismology (IRIS). Coulomb Failure Criterion used to calculate static stress changes and compute with Coulomb 3.3 software. To calculate the dynamic stress changes, volumetric strain multiplied by a Bulk constant and using Finite Difference method approach to solve the volumetric strain value. The results show that the value of static stress changes due to the earthquake in January 25, 2014 only 0.1 kPa, while the result of two other earthquakes near zero. With that static stress changes values, earthquake events can not influece physical condition of Merapi’s magma chamber. Dynamic stress changes due to the earthquake in January 25, 2014 reached about 14 kPa, so that dynamic stress changes can influence physical condition of Merapi’s magma chamber, but not eruption instantly. While due to two other earthquakes only 0.3 kPa and 0.4 kPa, so its can not influence physical condition of Merapi’s magma chamber.
Kata Kunci : Merapi; eruption; earthquake; Coulomb Stress
