New insights into Kawah Ijen’s volcanic system from the wet volcano workshop experiment
Volcanoes with crater lakes and/or extensive hydrothermal systems pose significant challenges with respect to monitoring and forecasting eruptions, but they also provide new opportunities to enhance our understanding of magmatic–hydrothermal processes. Their lakes and hydrothermal systems serve as reservoirs for magmatic heat and fluid emissions, filtering and delaying the surface expressions of magmatic unrest and eruption, yet they also enable sampling and monitoring of geochemical tracers. Here, we describe the outcomes of a highly focused international experimental campaign and workshop carried out at Kawah Ijen volcano, Indonesia, in September 2014, designed to answer fundamental questions about how to improve monitoring and eruption forecasting at wet volcanoes.
A Simple and Low-Cost Data Acquisition System with Multi-Nodes Facility for Geophone Array Sensors
Didik R. Santoso, Sukir Maryanto, Ahmad Nadhir, and Toko Sugiharto
In this paper, a simple data acquisition (DAQ) system, which dedicated for commercial geophone array sensors, has been developed with small budget. The DAQ system was built based on RS-485 Fieldbus network; it can handle many sensors in a distributed style. The DAQ system is a modular system; it consists of a master module as a control unit and several slave modules as sensing units. On each slave module, signals from several geophones will be filtered, amplified, converted to digital data, and then sent to the master module to be displayed and processed. On the experimental test, the developed DAQ system can detect seismic signals from several installed geophone sensors simultaneously. The system has capability to identify frequencies of the seismic signals properly. The delay time among the geophone sensors is possible calculated by using software that was installed on the master module.
Keywords: DAQ-system, multi nodes, geophone array.
Interpretation Capacity of Natural Waters (Sediments) and Depth at Belawan Kaligedang around Ijen Mount with Geoelectric Methods Resistivity Mapping and Metal Content (Fe, Pb) of Natural Waters
Wiyono, Soemarno, Sukir Maryanto, Arief Rachmansyah
The study was conducted by using geoelectric resistivity method with locations in village Belawan, Kaligedang of Ijen Mount about the source 1, position (S 7° 59.706’ E 114° 11.531’), altitude 1029 m above sea level and source 2, position (S 7° 59.66’ E 114° 11.545’), altitude 1000m above sea level. Measurements and analysis date from serounding source 1 and source 2 found the cross-section figures 1 and 2 and found that the depth of the water. With table 1 Resistivities of mineral (Telford W.M, Applied Geophysics edition 1976), We found varies of depth from 0 to approximately 15 m with a maximum depth of approximately 24.9 m, a width of nearly all the 200 m. Meanwhile, sources 2 to the depth of the water varies from 0 to about 9.94 m, with a maximum depth of approximately 17.3 m. From the results of chemical analyzes of water samples taken from the source above (1) and the bottom source (2) is attached as Atomic Absorption Spectroscopy using result The above source containing Fe with average levels (0.15 ± 0.00) mg/L and lower resource containing Fe with average levels (0.19 ± 0.01) mg/L. And the second water source does not contain Pb.
Keywords: Interpretation, Geoelectric, Natural waters, Resistivity, Ground water
Interpretation of Natural Water (Sediments) Depth Patterns around the River Banyuputih Situbondo East Java with Method Geoelectric Resistivity Sounding
Wiyono, Soemarno, Sukir Maryanto, Arief Rachmansyah
The study was conducted using the method of geoelectric resistivity configuration Schlumberger conveniently Around River Banyuputih Situbondo, East Java with the number of points Sounding as much as 11 Datum points and then having processed using software progress 3 obtained the depth of ground water also by using a reference table Telford page 452 that the resistivity of the water soil or Natural waters (sediments) ranges between 1 – 100 ohm meter. Interpretation (from table) obtained depth of the Naturalwater below the dots sounding, found variations in the depth of 1 m to 46 m. And the pattern variation depth after drawn using software surfer obtained unique pattern of depth soilwater. From the analysis of dats found that the interpretation of depth of groundwater the southern lowland and getting high towards the north of The research area (east beside of The river Banyuputih) and east of the sea and at its peak on the coordinates (500m; 2000m) on the research area or coordinate (114° 14’ 16.2’’ Long. East; 7° 46’ 4.9’’ Lat. South).
Keywords: Interpretation, Geoelectric, Resistivity, Resistivity, Natural water, Sediments
Magnetotelluric-Geochemistry Investigations of Blawan Geothermal Field, East Java, Indonesia
An integrated magnetotelluric (MT) and geochemical study of the Blawan geothermal field has been performed. The character of the hot springs, the reservoir temperature, and geothermal reserve potential of Blawan geothermal field are assessed. MT measurements, with 250 m up to 1200 m spacings, were made at 19 sites, and 6 locations at the Blawan hot springs have been sampled for geochemical survey. The results of 2D modelling indicated that the geothermal system in the research area consisted of a cap rock zone (≤32 Ω•m), reservoir zone (>32 – ≤512 Ω•m), and heat source zone (>512 Ω•m), and also identified faults. The characteristics of the hot spring water were identified through analyzing the major and minor elements. A ternary diagram (Cl-SO4-HCO3) showed that the Blawan hot springs consist of bicarbonate water (at locations of AP-01, AP-02, AP-03) and chloride water (at locations of AP-04, AP-05, and AP-06), with a reservoir temperature of approximately 90 °C based on the Na–K–Ca geothermometer results. An estimate of the geothermal energy using the volumetric method, gave a total geothermal reserve potential of 1.823 MWe.
Keywords: magnetotelluric, geochemistry, geothermal, Blawan, reservoir.
Temporal Changes of Complete Bougeuer Anomalies at Bromo Volcano, East Java, Indonesia
Sukir Maryanto, Sri Dwi Wuryani, Aulia Kharisma Nugraha, Andre Prayogo, Syegi Lenarahmi Kunrat, Ahmad Basuki
Bromo is one of the most active volcanoes located in Tengger Caldera, East Java, Indonesia. Historically, Bromo volcano was erupted about 50 times since 1775. Temporary gravity observation has been conducted at Bromo volcano in 1997, 2001 and 2014 to identified the temporal changes of Complete Bouguer Anomaly (CBA). The results of the research noted that for 17 years, subsurface conditions from Bromo volcano has changed. The changes in this period caused by volcanic activity from Bromo eruption, especially after eruption in 2000, 2004, 2010, and 2011. Based on the results of the gravity survey, Bromo volcano’s structure has changed both in terms of morphology as well as geologically. This temporal changed was identified in the value of CBA around Bromo volcano. The CBA data is representative to determine the dynamic of magma chamber beneath Bromo volcano. In 1997, CBA obtained with range from 200 to 620 mGal and in 2001, the CBA contour’s range is wider than 1997, that is from -320 to 120 mGal. The wide range affected by large distribution observed data with high vertical-horizontal topographic. The CBA 2014 distributed in the range of 454 to 496 mGal from 250 m and mean height as 350 m vertical topographic each datum.
Keywords: Bromo, Volcano, Gravity, Complete Bouguer Anomaly, Temporal Changes.
Polarization of Volcanic Tremor Recorded at Bromo Volcano, East Java, Indonesia
Maryanto Sukir, Arisalwadi Meidi, Syahra Vanisa and Triastutty Hetty
Bromo volcano is one of series of active volcanoes in Indonesia, located in Tengger caldera, Probolinggo, East Java. Bromo volcano has increased the volcanic activity in the end of 2015 to early 2016. This research was conducted to determine the characteristic of Bromo’s volcanic tremors and the depth of its source using polarization method. The polarization of the volcanic seismic signal is part of the monitoring system. The basic parameters related to seismic wave polarization analysis are azimuth angle, back azimuth angle, incidence angle, and hypocenter. The obtained depth from the analysis of polarization is about 1500 meters beneath the crater as the source of volcanic tremor.
Keywords: volcanic tremor, polarization method, azimuth angle, back azimuth angle, incidence angle, depth source.
Geo Techno Park potential at Arjuno-Welirang Volcano hosted geothermal area, Batu, East Java, Indonesia (Multi geophysical approach)
Arjuno Welirang Volcano Geothermal (AWVG) is located around Arjuno-Welirang Volcano in Malang, East Java, about 100 km southwest of Surabaya, the capital city of East Java province, and is still an undeveloped area of the geothermal field. The occurrence of solfatara and fumaroles with magmatic gasses indicated the existence of a volcanic geothermal system in the subsurface. A few hot springs are found in the Arjuno-Welirang volcanic complex, such as Padusan hot spring, Songgoriti hot spring, Kasinan hot spring, and Cangar hot spring. Multi geophysical observations in AWVG complex was carried out in order to explore the subsurface structure in supporting the plan of Geo Techno Park at the location. Gravity, Magnetic, Microearthquake, and Electrical Resistivity Tomography (ERT) methods were used to investigate the major and minor active faulting zones whether hot springs circulation occurs in these zones. The gravity methods allowed us to locate the subsurface structure and to evaluate their geometrical relationship base on density anomaly. Magnetic methods allow us to discriminate conductive areas which could correspond to an increase in thermal fluid circulation in the investigated sites. Micro-earthquakes using particle motion analysis to locate the focal depth related with hydrothermal activity and electrical resistivity tomography survey offers methods to locate more detail subsurface structure and geothermal fluids near the surface by identifying areas affected by the geothermal fluid. The magnetic and gravity anomaly indicates the subsurface structure of AWVG is composed of basalt rock, sulfide minerals, sandstone, and volcanic rock with high minor active fault structure as a medium for fluid circulation. While using micro-earthquake data in AWVG shown shallow focal depth range approximate 60 meters which indicates shallow hydrothermal circulation in AWVG. The geothermal fluid circulation zones along the fault structure resulted in some hot springs in a central and north-western part of AWVG detected by the Electrical Resistivity Tomography, appear to be well correlated with corresponding features derived from the gravity, magnetic, and micro-earthquake survey. We just ongoing process to develop Arjuno Welirang Volcano & Geothermal Research Center (AWVGRC) located at Universitas Brawijaya Agro Techno Park, Cangar in the flank of Arjuno Welirang volcano complex. Due to our initial observations, AWVG has a great potential for a pilot project of an educational geo technopark development area.