ANALYSIS SPECTRAL AND HYPOCENTRE ON MOUNT SINABUNG VOLCANIC EARTHQUAKE ACTIVITY DURING MAY 2017

• Main Author: KUSUMAPUTRI (NIM : 10214013), OCTADIANTI
• Format: Final Project
• Language: Indonesia
• Subjects: Fisika
• Online Access: https://digilib.itb.ac.id/gdl/view/29862
• Institution: Institut Teknologi Bandung

Sinabung volcano is a cone-shaped strato volcano with a height of 2460 meters above sea level. Sinabung volcano is located in Karo, North Sumatera Province. Geographically, it's located at 3°10' North Latitude and 98°23.5' East Longitude. Monitoring of Sinabung volcano continues to be done because it still has a high earthquake activity. To understand the characteristics of volcanic earthquake and the source, it's necessary to determine earthquakes' hypocenter and do spectral analysis of occured earthquakes. Sinabung volcano's activities are recorded in several stations such as Sukanalu (SKN), Mardinding (MDD), Lau Kawar (LKW), Kebayaken (KBY), Gamber (GBR), Sigarang-garang (SGR), Sibayak (SBY). There are several software that is used such as, LS7_WVE to search for earthquakes recorded at at least 3 stations and determine the arrival time of p and s waves, Microsoft Excel to process data, Geiger’s Method With Adaptive Damping (GAD) to determine the coordinates x, y, z of seismic hypocenter, Origin Pro 7 to Fast Fourier Transform (FFT) and MATLAB to plot hypocenter and Short-Time Fourier Transform (STFT) in the form of spectogram, and Global Mapper to find the contour of Sinabung Volcano. Results obtained from the implementation of this research are 94 earthquakes. Based on the results of spectral analysis, depth, seismic signals and magnitude, the earthquake that occurred in Gunungapi Sinabung in May 2017 consisted of 79 Type A earthquakes, 7 Type B earthquakes, 5 volcanic hybrid, 2 low-frequency earthquakes, and l eruption. The average depth of the quake is at 0.2 - 1.5 km below sea level. The majority of earthquakes occur in the high frequency range, 7.5 – 10 Hz and magnitude 1 – 1.5.