Preliminary Results on Low Frequency Passive Seismic (LFPS) Study in Lake Toba

Abstract Sumatra Island is an island located in the subduction zone of Indo-Australian plate towards Eurasia. The geological structure on Semangko Fault. There active volcanic activity, such as Bukit Barisan Mountains, which makes vulnerable to eruptions. study was conducted Lake Toba, North Sumatra, using earthquake data from IRIS station. purpose this investigate amplitude determining presence fluid reservoirs (magma) and analyze volcanics Toba region Low Frequency Passive Seismic (LFPS) method by utilizing attributes maximum Vertical-to-Horizontal Spectral Ratio (VHSR), Power Density (PSD) Z, spectrum Z component, are used indicators connect subsurface reservoir looking at curve. Previous research has linked a peak vertical component frequency range 1-6 Hz. Based results analysis all attribute parameters obtained, anomaly VHSR spectrum, PSD amplitude, indicate that location with highest potential Northwest-Southeast around Samosir island. These support previous research. Volcanic activity relatively lower because values not too high.