Spectral and Fractal Analysis of Volcanic Tremor at Ijen Volcano, Indonesia

A volcanic tremor is one of the seismic events that is usually recorded at the Ijen volcano. In 2014 the status of the Ijen volcano had yet to be declared normal after being critical in 2012. Many volcanic tremors are still recorded since then. This study aims at analyzing the volcanic tremors of Ijen volcano using the January to March 2014 seismic recording data obtained from the Center for Volcanology and Geological Disaster Mitigation, Bandung, Indonesia. We analyzed the spectra and fractal of volcanic tremors. Fractal and spectral analysis was conducted to investigate the dynamical system regarding the sources of the mechanism. Spectral analysis was estimated using the Fast Fourier Transform method, and fractal analysis was estimated using the regularization method. The spectra of a single volcanic tremor had frequencies of 1.1-1.5 Hz. Fractal analyzes were performed to identify dynamic systems. The fractal of a single volcanic tremor had a dimension of 2-2.3. Based on the frequency and fractal dimension values obtained, we suspect that the trigger of the volcanic tremors of the Ijen volcano is a fluid-filled crack mechanism.