by Agfianto Eko PUTRA, Wiwit SURYANTO, Agung Nugraha SULISTYANA
Seismic data analysis of the 2006 Merapi volcano eruption has been carried out using the Continuous Wavelet Transform (CWT) and the Wavelet-based Decomposition and Correlation (WAVEDECOR) combined with the Fast Fourier Transform (FFT). The CWT is used to show the frequency pattern of the event while the WAVEDECOR is used to denote the frequency band of the signal. The CWT and the WAVEDECOR are supported by the FFT to ensure the dominant frequency of the observed signals. The results show that visual patterns and dominant frequency distribution of certain events, including the VT-A, the Low Frequency (LF), the VT-B, tremor, multiphase and lava avalanche. The result from this analysis was then compared with related eruption signal of Merapi in 1996 to determine the pattern similarity. The comparison results show almost identical results for dominant frequencies in VT-A events as well as MP events. The findings in the VT-B event showed that the dominant frequency pattern was slightly different from the 1996 data which showed at medium to high-frequency while for the 2006 data showed only at a medium frequency.