Analisis Spektral dan Waveform Cross Correlation Tremor Vulkanik Gunungapi Bromo Jawa Timur Pada Letusan Tahun 2016
Meidi Arisalwadi, Sukir Maryanto, Hetty Triastuty
Gunungapi Bromo merupakan salah satu dari serangkaian gunungapi aktif di Indonesia yang terletak di dalam kaldera Tengger, Kabupaten Probolinggo, Jawa Timur. Gunungapi Bromo mengalami peningkatan aktivitas vulkanik pada akhir tahun 2015 sampai awal tahun 2016. Penelitian dilakukan untuk menentukan karakteristik tremor vulkanik. Metode yang digunakan untuk menentukan karakteristik dari tremor vulkanik adalah analisis spektral dan analisis waveform cross correlation. Analisis spektrogram didapatkan nilai frekuensi 1-8 Hz untuk tremor vulkanik Gunungapi Bromo. Hasil analisis spektral tremor vulkanik Gunungapi Bromo dapat dilihat berdasarkan nilai puncak-puncak frekuensi yang tidak beraturan yang berarti tremornya tipe spasmodik. Berdasarkan Pola puncak-puncak dari analisis spektral tremor yang menggunakan 3 stasiun memiliki pola yang sama dan analisis waveform cross correlation tremor vulkanik Gunungapi Bromo diindikasikan berasal dari sumber mekanisme yang sama karena didapatkan nilai koefiesien cross correlaton cukup baik yang berkisar diantara 0,6-0,8.
Kata Kunci: seismik, tremor, spektral, spektrogram, waveform cross correlation
Pemetaan Suhu Permukaan Tanah Pada Komplek Kawah Wurung-Ijen, Kabupaten Bondowoso, Jawa Timur Dalam Penentuan Manifestasi Panas Bumi
Endah Juniarti, Sukir Maryanto, Adi Susilo
A research using remote sensing have been done on Kawah Wurung-Ijen. This research was conducted to analyze the distribution of land surface temperature and to identify the geothermal manifestations. The land surface temperature was obtained by using emissivity method of calculating the Normalized Difference Vegetation Index (NDVI). Remote sensing data was used more secund data from Landsat 8. The result shows that the research area has the land surface temperature distribution in ranges 10°C to 50°C. The interpretation shows any anomalous area in ranges 31°C to 50°C that indicated as geothermal potential area. The anomalous are associated with volcanic areas. In the West is associated with Mt. Genteng, in the North is associated with Mt. Gending Waluh. In addition, there is also an anomaly in the East precisely around kolovium of Mt. Kukusan.
Keywords: Land surface temperature, remote sensing, geothermal.
Penentuan Sebaran Suhu Permukaan Tanah Daerah Prospek Panasbumi Kawah Wurung – Ijen, Kabupaten Bondowoso – Banyuwangi Jawa Timur Dengan Menggunakan Metode Penginderaan Jauh
Surya Aji Ermanto, Sukir Maryanto, Adi Susilo
Has conducted research using remote sensing methods being located in the mountain complex Ijen, Bondowoso – Banyuwangi, East Java as preliminary data to assist in the design of geothermal exploration survey. Remote sensing data used are images from Landsat 8. Landsat 8 infrared thermal image is processed as land surface temperature data. Processing land surface temperature using a single band. Methods in this study begins with finding NDVI (Normal Differential Vegetation Index), which is the value used to state how dense vegetation in an area. After it obtained the value of the fraction of vegetation and emissivity of land used for the determination of the distribution of land surface temperatures. The surface temperature of this land will be used as a guide in making the design of a geophysical survey in geothermal exploration further. Because geothermal areas associated with land surface temperatures were relatively high. Based on the results of data processing of remote sensing, land surface temperatures were relatively high in the area around the Kawah Wurung and Girimulyo that has a land surface temperature ranges between 3060ºC.
Hypocenter Determination And Clustering Of Volcano-Tectonic Earthquakes In Gede Volcano 2015
Aulia Kharisma Nugraha, Sukir Maryanto, Hetty Triastuty
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.
Determination Of The Direction Of Hot Fluid Flow In Cangar Area, Arjuno-Welirang Volcano Complex, East Java Using Self Potential Method
Dafiqiy Ya’lu Ulin Nuha, Sukir Maryanto, Didik Rahardi Santoso
Research with self potential method has been done in Cangar area of Arjuno-Welirang volcano complex, East Java. The purpose of this study was determined the direction of hot fluid flow. This hot fluid forms a geothermal manifestation of hot springs. Data acquisition has been done using fixed electrode configuration with interval 5 meters in 5 lines. In this configuration there are two porous pot electrodes, one of them set in fixed station and the other as mobile station. Based on the potential distribution value of the isopotential map, the lowest potential value about -54,5 mV and the highest value about 89,4 mV, so that in Cangar area can predicted the direction of hot fluid flow from southeast to northwest. Based on the results of this research in the direction of hot fluid flow can provide information about hydrothermal system in Cangar area for study of geothermal potential of Arjuno-Welirang Volcano complex, East Java
Keywords: Self potential; fixed base configuration; isopotential map; fluid flow.
Identifikasi Sistem Panas Bumi Daerah Cangar, Jawa Timur dengan Metode Magnetotelurik
Rahmawati Rahmawati, Sukir Maryanto, Adi Susilo
The research has been done in Cangar area of complex Mt.Arjuno-Welirang, East Java. This research using magnetotelluric method. The purpose of this research is to identify the geothermal system of research area based on its resistivity value. Acquisition of magnetotelluric data done in 11 point with spaces 70 meters up to 150 meters. Magnetotelluric measurement points is divided into 5 profile. Based on the result of data processing given range resisitivity value in research area between 4 W.m up to 2000 W.m. The result of modeling geothermal system in Cangar indicated of caprock (≤21 W.m), reservoir (21 W.m – 167 W.m) and a heat source (≥167 W.m). Geothermal Cangar is controlled by Cangar fault.
Kata kunci: magnetotelluric, resistivity, geothermal, Cangar