Hypocenter Determination and Clustering of Volcano-tectonic Earthquakes in Gede Volcano 2015

Gede volcano is an active volcano in West Java, Indonesia. Research about determination the volcano-tectonic earthquake source positions has given results using volcano-tectonic earthquakes data from January until November 2015. Volcano-tectonic earthquakes contained deep (VT-A) have frequency (maximum amplitude) range 5 – 15 Hz. Furthermore, they contain shallow earthquake, VT-B have range 3-5 Hz and LF have range 1-3 Hz. Geiger's Adaptive Damping (GAD) methods used for determining the hypocenter of these volcano-tectonic (VT) events. Hypocenter distribution divided into 4 clusters. Cluster I located in the crater of Gede volcano dominated by VT-B earthquakes their depth range 2 km below MSL to 2 km above MSL including the VT-B swarm. The seismic sources in cluster I indicated dominant due to the volcanic fluid or gas filled in conduit pipes. Cluster II located at the west of Gede volcano caused by Gede-Pangrango fault-line dominated by VT-A earthquakes with depths range 1.5 km below MSL to 700 m above MSL. Cluster III located in the North of Gede volcano dominated by VT-A events there caused by graben fault area with those depths range 7.5 – 1.65 km below MSL. Cluster IV located in South West of Gede volcano contained VT-A earthquakes with depth range at 10 km below MSL and VT-B earthquakes this depth 2 km below MSL. Due to magma intrusion filled into fractures of the fault in the West of Gede volcano this shallow magma filling-fractures and degassing in subsurface assumed dominates the volcano-tectonic events from January to November 2015 due to faults extends from North to South occured in the West of Gede volcano

Hypocenter Distribution of Low Frequency Event at Papandayan Volcano

Papandayan volcano is a stratovolcano with irregular cone-shaped has eight craters around the peak. The most active crater in Papandayan is a Mas crater. Distribution of relocated event calculated using Geiger Adaptive Damping Algorithm (GAD) shows that the epicenter of the event centered below Mas crater with maximum rms 0.114. While depth of the hypocenter range between 0-2 km and 5-6 km due to activity of steam and gas

Analisis Non Linier Tremor Vulkanik Gunungapi Raung Jawa Timur–Indonesia

Penelitian mengenai aktifitas tremor vulkanik gunung Raung yang terekam pada bulan Oktober 2012 telah dilakukan. Data yang digunakan pada penelitian ini yaitu data tremor vulkanik yang terekam pada tanggal 17 Oktober sampai 16 November 2012. Penelitian dimulai dengan seleksi event tremor vulkanik yang jelas. Selanjutnya dilakukan rekonstruksi diagram attraktor dari tremor vulkanik gunung Raung dengan menggunakan teorema delay embedding. Delay time untuk merekonstruksi diagram attraktor ditentukan dengan menggunakan Metode Mutual Information (MI) dan didapatkan delay time tremor vulkanik gunung Raung dalam range 0,08 s - 0,09s. Dimensi embedding ditentukan dengan menggunakan metode False Nearest Neighbour (FNN) dan didapatkan dimensi embedding tremor vulkanik gunung Raung dalam range 4-5. Dengan menggunakan delay time dan dimensi embedding yang didapatkan maka diagram attraktor dapat direkonstruksi. Dimensi fraktal dihitung dengan menggunakan metode dimensi korelasi dan didapatkan nilai dimensi fraktal tremor vulkanik gunung Raung berkisar 2,91 – 3,35. Nilai Lyapunov exponent tremor vulkanik gunung Raung didapatkan berkisar 0,016 – 0,030. Berdasarkan dimensi fraktal dan Lyapunov exponent tremor vulkanik gunungapi Raung bersifat kaotik

Perubahan Spasial Dan Temporal Karakteristik Gempa Vulkanik a Dan Vulkanik B Gunungapi Ijen Jawa Timur

Beberapa penelitian telah dilakukan untuk mengkaji aktivitas Gunung Ijen yang merupakan salah satu gunungapi aktif tipe A di Indonesia. Tingginya aktivitas hidrotermal yang berasal dari kawah Gunung Ijen mengindikasikan adanya patahan-patahan yang membantu jalur migrasi fluida bawah permukaan. Penelitian ini dilakukan untuk menentukan karakteristik gempa vulkanik tipe A dan tipe B serta menentukan distribusi hiposenter dari kedua gempa tersebut. Aktivitas seismik Gunung Ijen direkam oleh lima stasiun seismik (DAM, POS, PSG, IJEN, KWUI) yang tersebar di sekitar kawah. Analisis gempa vulkanik dilakukan berdasarkan waveform dan spektral gempa serta distribusi hiposenternya. Dari hasil penelitian ini didapatkan frekuensi dominan gempa vulkanik A sekitar 3,99 Hz – 9,75 Hz. Sedangkan frekuensi dominan gempa vulkanik B sekitar 1,97 Hz – 11,37 Hz. Hiposenter gempa vulkanik A berada pada kedalaman 2000 – 3000 meter di bawah pusat kawah aktif. Sedangkan hiposenter gempa vulkanik B berada pada kedalaman 70 – 3000 meter di bawah pusat kawah aktif. Dari aktivitas gempa vulkanik B dihasilkan horizontal crack yang berada pada kedalaman 1000 – 2000 meter di bawah pusat kawah aktif

Physical Analysis of Mount Talang – West Sumatera Activity Based on the Spectral Characteristics and Hypocenter Estimation of Volcanic Earthquakes

Volcanic activity of Mount Talang – West Sumatera is very interesting to be studied and to be learned, because its activity was influenced by geological structures in the vicinity of Mount Talang which is a depression zone of Sumatera Fault. This study aimed to investigate the characteristics of volcanic earthquakes at Mount Talang in the period of January to March 2013 based on the spectral analysis and hypocenter analysis. In addition, the velocity estimation was carried out to determine the value of the corresponding seismic wave velocity in the vicinity of Mount Talang. Volcanic earthquake signals obtained from four seismic stations Gabuo,Ketah, Puncak and Kopi. The seismic signals are selected first and then grouped by the type of the earthquake. Spectral analysis is performed to determine the value of the dominant frequency and the cut-off frequency (corner frequency) of volcanic earthquakes. Hipocenter analysis aims to determine the hipocenter depth of vulcanic earthquake. Based on the spectral analysis, the frequency content of volcanic earthquakes ranged from 3.12 to 17.87 Hz. The high frequency content can be correlated with geological structures in the vicinity of Mount Talang which is in the form of cracks / faults as a manifestation of the Great Sumatera Fault zone. Based on a formula which is known before, it can be seen that the estimation of rupture length is ranged between 67 to 142 m. The hypocenter distribution of volcanic earthquakes ranged from 2 to 9 km below the summit of Mount Talang. Based on the results of seismic wave velocity estimation that fits around Mount Talang is at the velocity between 2.5 to 2.8 km / s. Where the condition of the surrounding medium is still relatively compact