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The ever-increasing use of fossil fuels causes the climate to become unbalanced due to the resulting pollution. Renewable energy is gaining widespread adoption because it is more cost-effective and eco-friendly. Using water as micro-hydro power plants or PLTMH can be a viable alternative to non-renewable fuel sources. Indonesia is one of the countries with the greatest application potential for micro-hydro power plants or PLTMH, particularly in Batang Regency, Central Java Province. This study focused on reducing the use of fossil fuels as a source of electricity in Batang Regency by utilizing water resources. Environmental approaches and hydrological analysis were employed in this study to achieve precise and optimal PLTMH planning outcomes. The results of the analysis indicated that the total discharge required to operate the PLTMH turbine is 2.22 m3/s with an 80% mainstay discharge, while the design flood discharge is 113,679 m3/s (Q100year). Implementing micro-hydro power plants or PLTMH in Batang Regency could be the first step in Indonesia’s transition from fossil fuels to renewable energy sources.

In rock magnetism, Vibrating-Sample Magnetometer (VSM) data displays magnetic moment in specific magnetic field applied in descending and ascending magnitude, which results in a pattern called hysteresis loop. This loop characterizes different magnetic materials depending on its shape. In recent years, the usage of computer software to analyze hysteresis loop has become necessary due to its precision. Easily executable, intuitive, and user-friendly open-source programs for analyzing VSM data are still not widely available despite their necessary utilization. HYSGUITS was designed with this issue in mind to further improve the development of tools in this field. HYSGUITS is a Graphic User Interface (GUI) to analyze the hysteresis loop of VSM data. MATLAB is a suitable base for producing this GUI compared to other programming language due to its sophisticated features and clean data visualization. This software is able to visualize hysteresis loop in different ways, mainly through the difference of ascending with descending magnetization value and its 1stderivative. The GUI displays the graph as an interactive plot window which provides detailed observation on each data points, supported by features such as interpolation and smoothing. This article introduces of the functionalities of HYSGUITS and demonstrates its utilization with example use case.

Referring to the Indonesian earthquake source and hazard map published by the National Earthquake Center (Pusgen) in 2017, it was stated that there were 34 active faults on the island of Java and could potentially be a source of earthquakes with earthquake strength more than the 6.5 M scale. Each potential source of earthquake needs to be carried out detailed research on each fault that is declared active so as to reduce uncertainty in the seismic hazard analysis. Due to limited funding and human resources researching, it is necessary to make research priorities based on the level of urgency. By utilizing decision making analysis techniques, priority of research is carried out by considering several aspects, such as the magnitude of the earthquake that may occured possible economic impact factors, population density and the level of importance of a region on a national and international scale. From the modeling results, it is shown that faults that have the potential to become earthquake sources that are located near large cities are a top priority for detailed research such as the Lembang, Semarang and Surabaya Faults.

Arjuno-Welirang Mountain is located in East Java province, which is a type of stratovolcano with an altitude of 3,339 m for Arjuno and 3,156 m for Welirang. The Arjuno-Welirang geothermal system is a volcanic geothermal system. Magnetotelluric is the most commonly used geothermal exploration method because of its deep penetration and sensitivity to conductive zones. The Magnetotelluric method measures 103 MT points in the field of geothermal systems in the South of Mount Arjuno-Welirang. In this study, the 3D inversion model of Magnetotelluric data was used to reduce the ambiguity of 2D Magnetotelluric inversion data. 3D Model Inversion uses WinGlink and 3DModEM. The steps of Magnetotelluric processing consist of time-domain conversion to the frequency domain, cross power selection, data smoothing, static effect correction, 2D and static strips, interpolation, masking, 3D inversion, and interpretation of inversion models. The 3D model inversion consists of 3D mesh grid parameters used by the NonLinear Conjugate Gradient Algorithm. 2D Inversion Modelling was done by the NLCG method, which produces a 2D model with an RMS error of 1.7%. 3D Inversion modeling was done by the NLCG method producing a 2D model with a value of RMS error of 2.83%. The geothermal system of the Arjuno-Welirang geothermal region consists of a layer of veil rock with a type of resistivity value of 5-11 Ωm, a middle resistivity zone with a value range of 11-76 m acting as a reservoir, and a high resistivity zone with a range of 76-500 Ωm or commonly called heat source. The results of the 3D inversion model indicated a range of low resistance types (hood rock layers) that have a thickness of 1200 - 1700 m, the value of this type of resistance is below the surface with a thickness of ±500-600 m. Thus, the Mt. Arjuno-Welirang is a geothermal prospect area.

A noise that recorded at magnetotelluric acquisition data makes the data quality not good enough, so the information obtained after data processing might not be correct or not suitable for the subsurface condition. Several characters of noisy magnetotelluric data are the spiky shaped and non-stationarity time-series curves. This non-stationarity character can't be handled by the Fourier Transformation process. This research used Empirical Mode Decomposition (EMD) in the original of Huang as a filtering method in order to overcome the non-stationarity. This method decomposed the signal into a group of oscillation mode called Intrinsic Mode Decomposition (IMF). It is one of the best IMF chosen as the filtering result by spectrum analysis in the frequency domain. This work used magnetotelluric data from a station that had three components with different frequency sampling, which was 15 Hz, 150 Hz, and 2400 Hz. IMF filtering method then applied to the data resulting in a smoother times-series curve with the suppressed non-stationarity character. This research showed that EMD filtering can be implemented at magnetotelluric data processing and emphasized the effect caused by noise.

Volume magnetic susceptibility measurements have been widely used in numerous studies related to river sediment characterization. A study of the transport distance effect toward the frequency-dependent volume magnetic susceptibility is needed to identify the superparamagnetic grain behavior in river sediments. The purpose of this study is to identify the presence of superparamagnetic grains and to obtain the relation between transport distances and frequency-dependent volume magnetic susceptibility in river sediments. The sediment samples were taken and measured by using the Bartington MS2B Susceptibilitymeter at two different frequencies of 470 Hz and 4700 Hz. The measurement results show that the sediment transport distance is directly proportional to the frequency-dependent volume magnetic susceptibility. Superparamagnetic grain content is identified to tend to be higher as the distance of sediment transport increases.

Earthquake can be caused by several things, one of which is due to an active fault. To mitigate earthquake disasters that can be caused by the Probolinggo Fault, measurement of the microtremor geophysical method is carried out to analyze seismic vulnerability. In this study, the microtremor measurements were carried out on 30 measurement points. The data obtained from measurements are then processed using EasyHVSR software to obtain natural frequency (f0) and natural amplification (A0) values. This value is then used to create a microtremor microzonation map, which is seismic vulnerability index, based on natural frequency and amplification . it founded that low natural frequency mostly founded on eastern of measurement area, caused by thick sedimentary from Lamongan volcanic. High amplification mostly founded from middle to western area, and high seismic vulnerability index founded on western of measurement area, include Maron and Krucil Sub-district. It means seismic wave can very destructive on those area.

Magnetotelluric (MT) research was conducted to map the fault structure in the western part of East Java. The advantage of the magnetotelluric method is its deep penetration because it propagates at a low frequency so that it can detect resistivity anomalies that are thought to be faults. The measuring path of the magnetotelluric method covered the Surabaya and Gresik areas. Research conducted in densely populated areas thus it requires a noise reduction process to improve the quality of the data. Performing the robust processing with Rho Variance parameters and editing XPR is an effort to reduce noise and to improve the quality of magnetotelluric data. The robust processing result of 5 (five) sounding MT data using the Rho Variance parameter can improve the quality of magnetotelluric data by increasing the coherence value of 2.128% (MT01), 2.804% (MT02), 2.378% (MT03), 3.508% (MT04), and 3.129% (MT12). Meanwhile, the editing XPR process can increase the coherence value of 0.184% (MT01), 7.155% (MT02), 9,364% (MT03), 0.784% (MT04), and 0.628% (MT12). Escalation of coherence value by implemented the Rho Variance and Editing XPR means that two methods are sufficient effectively to raise the confidence level of MT data processing and interpretation result.

The pull-up effect is the condition of lithology elevated in seismic imaging because of rapid seismic wave propagation through carbonate build-up on it. Pull-up effect conditions can lead to misinterpretation, so it needs to be corrected until the actual geological conditions are obtained. This research was conducted in the JAX-field working area of PT Pertamina Hulu Energi ONWJ. The target reservoirs of this study are in the Main (Upper Cibulakan) Formation under the Carbonate Parigi Formation. The reflectors of the target reservoirs show pull-up effect in time domain seismic data. Thus, building a velocity model for velocity anomaly correction is needed to reduce uncertainty for structure maps and oil in place calculation. The method of correcting the pull-up effect in this study uses three variations of the velocity model: variation structurally controlled model, variation RMS velocity with well control, variation calibrated RMS velocities model. The three variations of the velocity model result can correct the pull-up effect on JAX-Field. Velocity model with variation RMS velocity with well control had the lowest error with 17,31 feet average of depth difference with actual depth from well. Based on three velocity models, the value of original oil in place on the JAX-32 reservoir surface had a range of 59,14-84,59 mmbo, while on the JAX-35A surface has a range of 27,77-31,23 mmbo. These values can be considered in reserve calculation sensitivity.

Environmental education can be applied to attitudes and behavior from an early age. This service activity is carried out to increase the understanding and awareness of SMPN 1 Sumbang students about the environment through productive aquaponic cultivation. Besides that, it also develops student character, so that they are active in protecting the surrounding environment through positive activities during the Covid 19 pandemic. Student responses were carried out by pre and post test with six questions. The results of the activity showed a change in behavior and an understanding level of 60%, this shows that the introduction of aquaponic cultivation can help students better understand the importance of protecting the environment both at school and at home.

Gravity survey is one of the passive geophysical techniques commonly used to delineate geological formations, especially in determining basement rock and the overlying deposit. Geologically, the study area is made up of thick quaternary alluvium deposited on top of the older basement rock. The Muda River basin constitutes, approximately, of more than 300 m of thick quaternary alluvium overlying the unknown basement rock type. Previous studies, including drilling and geo-electrical resistivity surveys, were conducted in the area but none of them managed to conclusively determine the basement rock type and depth precisely. Hence, a regional gravity survey was conducted to determine the thickness of the quaternary sediments prior to assessing the sustainability of the Muda River basin. Gravity readings were made at 347 gravity stations spaced at 3–5 km intervals using Scintrex CG-3 covering an area and a perimeter of 9000 km2 and 730 km, respectively. The gravity data were then conventionally reduced for drift, free air, latitude, Bouguer, and terrain corrections. These data were then consequently analyzed to generate Bouguer, regional and total horizontal derivative (THD) anomaly maps for qualitative and quantitative interpretations. The Bouguer gravity anomaly map shows low gravity values in the north-eastern part of the study area interpreted as representing the Main Range granitic body, while relatively higher gravity values observed in the south-western part are interpreted as representing sedimentary rocks of Semanggol and Mahang formations. Patterns observed in the THD anomaly and Euler deconvolution maps closely resembled the presence of structural features such as fault lineaments dominantly trending along NW-SE and NE-SW like the trends of topographic lineaments in the study area. Based on power spectral analysis of the gravity data, the average depth of shallow body, representing alluvium, and deep body, representing underlying rock formations, are 0.5 km and 1.2 km, respectively. The thickness of Quaternary sediment and the depth of sedimentary formation can be more precisely estimated by other geophysical techniques such as the seismic reflection survey.

Reservoir’s quality is very important in exploration of oil and gas. This quality can be used to determine the productive field including the reserve itself. To analyse the reservoir quality, net pay thickness needs to be determined. However, different quality of logging tools will affect the log reading and thickness interval. Therefore, it needs to be normalized in order to equalize the reading of minimum and maximum log values in interest zone. This study is intended to interpret the impact of gamma ray normalization on net calculation. The net pay calculation is carried out with and without normalization. To do normalization, cumulative percentile used are 3% and 93%. For instance, before normalization, the highest net pay in PE_35 is 12ft. After P93 and P3 normalization, the highest net pay value become 13.5ft and 51.5ft respectively. If the net pay value of PE_35 using P3 normalization is compared to the net pay value before normalized, then the normalized value is optimized more than 5%, which is a good amount of optimization. Thus, to obtain an optimistic net pay value, normalization must be done. To conclude this study, 3% cumulative percentile normalization method has shown the most optimistic net pay value increase.

Ancient civilizations in Jombang left many historical relics in the form of temples, artifacts, and other archeological sites. Kedaton site is one of the newly discovered archeological sites. This site is buried under a few meters thick of Mount Kelud’s pyroclastic flow. Therefore, the distribution patterns of the site is needed to improve the excavation plan in order to maintain the structure of the site. One of the technical approaches that can be applied to map the site’s distribution in detail is geophysical survey. Geomagnetic method is a method commonly used in the case of archeological site investigations because of its non-destructive nature. The mapping process on Kedaton site is conducted by applying geomagnetic survey that utilizes physical parameters in the form of magnetic susceptibility. The reduce to pole filter is applied to magnetic data processing to aid interpretation, coupled with horizontal gradient method and analytic signal method further clarify the boundaries of magnetic anomaly sources. Reduce to pole filter indicates that the site’s brick detected as moderate to high magnetic anomaly values (more than 450 nT). This research succeeded in mapping clearly the boundaries of the site with an area of up to 6000 meters2 with the shape of the site resembling a building with several chambers. The main chamber is in the north which is the widest chamber, and small chambers are found on the south side.

Some heavy metals of Cd, Cu, Pb, and Hg polluted in Segara Anakan Cilacap, but no information on a specific heavy metal pollution in this area and an edible mud crab of Scylla serrata. The research aimed to know their distribution in this area and their accumulation of heavy metals from waters and sediments to Scylla serrata. The study was done using a survey method with purposive random sampling at six stations from Station SA-2-28 and SA-3-46 (with a high percentage mangrove canopy cover) to Station SA-2-24, SA-3-35, SA-1-10, and SA-3-16 (with a low percentage mangrove canopy cover). Three replications were done in the dry season conditions from July to September. The researcher took all samples with the water sampler tool, sediment core, and baited trap for sampling. Then, they were analyzed using Atomic Absorption Spectrophotometry (AAS) method. The result showed that the lowest heavy metals were at Station SA-2-28 and SA-3-46 and followed by Station SA-2-24, SA-3-5, SA-1-10, and SA-3-16 due to the high percentage of mangrove canopy cover, while the reserve order was due to the increased pollution in east side areas of Segara Anakan Cilacap. The heavy metal accumulation of Cd, Cu, Pb, and Hg has occurred from waters and sediments to Scylla serrata.

The subsurface geological condition of East Java is an area that is crossed by an active fault geological structure. The National Earthquake Center revised the Indonesian Earthquake Hazard and Source Map of 2017 with the discovery of new active faults surrounding the Kendeng Zone, East Java. This research was conducted using Magnetoteluric (MT) method which has high penetration therefore it was able to map the geometry of active deep fault structures beneath the surface. Measurements were made at 11 measuring points focusing on the Blumbang Fault (M6.6) in Lamongan District. 4 (four) lines were made from 11 existing measuring points. The lines were then modelled in 2D to describe the distribution of subsurface resistivity. The results showed an anomaly with low resistivity value which was indicated as Blumbang Fault in 4 section models. Section of line 1 and 2 indicated a fault in the NS-SE direction continuity to the northwest which became deeper to the south from 6 km to 9 km. Lines 3 predicted the fault with low resistivity value (

In recent years, formation evaluation and well logging analysis have been evolving from its measurements, accuracy and applicability to determine tough downhole environments. Thin bed Reservoir is one of the most challenging well logging analysis due to the complexity of the high content of clay minerals in the shaly-sand lamination layer (thin bed) which inherently affects the log data response in the form of high gamma ray values and low resistivity. This causes the thin lamination zone is identified as a non-reservoir zone. Meanwhile, worldwide 30 to 40% of the oil in-place resources are confined within thin beds. Seeing the problem in the prediction of thin bed reservoirs, this research is focusing on Enhancing and developing thin bed potential by reevaluating petrophysical analysis, applying Laminated Shally Sand Analysis and Monte Carlo Uncertainty Probabilistic for calculating petrophysical parameter distribution and validating the parameter with Log Image. Laminated Shally Sand Analysis implements Thomas Steiber Plot in order to give laminated shale distribution and porosity, whereas the water saturation is calculated using Waxman Smith’s Equation. From this research, well SSK has thin bed potential at 2521.45 - 2543.45 ft. Laminated Shally Sand Analysis also capable to improve thickness of netpay with the range of 40.35% based on probabilistic delivered from Monte Carlo.

Monitoring sumber panas bumi perlu dilakukan untuk memaksimalkan kegiatan eksplorasi dan pemanfaatan sumber energi, dengan melihat adanya aktivitas yang terjadi dibawah permukaan yaitu gempa mikro. Uji lokasi pada penelitian ini menggunakan metode Double Difference yang terdiri dari 2 tahap yaitu clustering dan relokasi, hasil relokasi hiposenter gempa mikro pada lapangan panas bumi “X” menunjukkan bahwa clustering terbagi menjadi 1 kelompok dengan jumlah event 260 data. Secara kuantitatif hasil dari proses relokasi hiposenter dengan metode Double Difference menghasilkan nilai eror yang jauh lebih kecil dibandingkan metode yang digunakan dalam penelitian sebelumnya yaitu Geiger Adaptive Damping. Metode Double Difference memiliki rata-rata nilai RMS eror sebesar 0.078 sedangkan, metode Geiger Adaptive Damping menghasilkan rata-rata nilai RMS eror sebesar 0.29. Secara kualitatif, hasil relokasi hiposenter terletak tepat dibawah jalur sumur pada daerah penelitian, dapat dibuktikan dengan hasil layout antara titik relokasi hiposenter dengan penampang 2D lintasan pengukuran metode Magnetotellurik pada daerah penelitian. Lintasan C,D dan E menujukkan hasil hiposenter berada pada sumur PPL-04ST, PPL-04AST, PPL-07, PPL-06, PPL-02AST, dan PPL02ST. Adanya titik relokasi hiposenter yang berada tepat dibawah jalur sumur produksi mengindikasikan adanya aktvitas pada zona tersebut seperti aliran-aliran fluida yang mengalir pada reservoir panas bumi. Maka dapat disimpulkan bahwa event gempa mikro yang terjadi merupakan akibat aktivitas-aktivitas produksi yang terjadi didalam sistem geothermal.

The industrial revolution 4.0 has required collaboration on the oil and gas industry sector. One of the problems is the technology transfer and the increasing of oil reserves supply. It needed to productivity analysis for reservoir rock characterization and subsurface profile that will determine technology transfer. This study was aimed to obtain the hydrocarbon reservoirs quality based on petrophysical parameters. The reservoir zone of JEONA_35 well in 1527.77 - 2067.21 ft. From NPHI and RHOB logs, there is a cross over in 1990-2020 ft that interpreted as oil fluid. The PHIE is 30 %, Sw is 20 % and Vclay is 10 %. Electrofacies analysis shows that the reservoir zone was located in Bekasap and Menggala Formations (1527.77 - 1889.25 ft). In Bekasap Formation, the gamma ray log pattern is a cylinder block shape and thick from the top until base formation, it deposited in the channel fill distribution with thin sandstones lithology. In Menggala Formation, gamma ray log pattern shows the uptrend bell shape that was deposited in the fluvial - delta distribution with thick sandstone. So, it can be concluded that JEONA_35 reservoir has a good quality with the water saturation is low relatively, so the oil saturation is high relatively.

This study aims to analysis the profile of data literacy ability by utilizing the local potential in Kampung Adat Kuta for junior high school students in Ciamis. This study used quantitative descriptive study with the test method. Subjects were 235 junior high school students in the academic year of 2019/2020 determined using purposive sampling techniques. The description test instrument was used to measure data literacy with four indicators, namely: exploring data, selecting data, converting data and maintaining decisions or making new decisions; this instrument has been validated by several lecturers. Data analysis generated was quantitative percentage. From the results of this study, test instruments for data literacy in junior high schools in Ciamis showed that the highest indicator was exploring data (39.32%), while the poorest was maintaining or making new decisions from data (29.47%). The results of this study indicate that the data literacy ability of secondary school students in Ciamis falls into the category of poor, so we need attention from educators to overcome the poor data literacy ability by practicing data literacy ability.

The existence of the kendeng fault passing Surabaya is still the subject of study by the researchers after being declared active by the National Earthquake Centre. The Surabaya was passed by two segments of the Kendeng fault, the Surabaya segment and the Waru segment, the two segments had an earthquake potential of 6.5 M. In the context of disaster mitigation and earthquake analysis, more detailed information is needed relating to the geometry and position of the earthquake source with certainty, so that the identification of earthquake sources is needed in more detail. The magnetotelluric method is one of the geophysical methods that is able to properly identify anomalous objects in tens of kilometers depth. Kendeng fault as a potential earthquake source, one of its segments across Surabaya can be identified using the magnetotelluric method. Megnetolelluric measurements were carried out as many as 15 points in the Surabaya region in order to identify the geometry of the kendeng fault. From the 3D resistivity model, the inversion of magnetotelluric data can be identified well with the Kendeng fault that crosses the city of Surabaya, both the Waru segment and the Surabaya segment at a depth of less than 8 km

Summary Geodetic study using Global Positioning System (GPS) has been done against the measurement of surface deformation in Java. Fault Kendeng is an active fault that extends from the eastern part of Java East to the western part of Central Java. The Java region obviously had a larger density difference because subduction rate is higher. This study indicated a new major earthquake will threat through East Java and causes tsunami to Bali, Lombok, Nusa Tenggara, and other beaches along the Flores Sea. Geological sheet of Surabaya showed the area of Surabaya and its surrounding are traversed by several structures geology liked the Lidah and Kedung Waru active faults which are associated with Lidah Anticline, Gayungan Anticline and Kedung Waru Anticline. Therefore, Surabaya and its surrounding areas had the potential of an earthquake. The measurement with gravity method can describe the condition of the structure under the surface which includes the interpretation of lithology as well as identify the presence of fault in the city of Surabaya. This study will become additional information for mitigation efforts and reviewing the spatial plan and territory in Surabaya.

Summary Java Island which is located north of the meeting between the two plates, that is The Indo-Australian Plate and the Eurasian Plate have several tectonic faults, as a form of stress accommodation generated by adjacent subduction South. Tectonic fault is a local deformation zone accommodate the movement of the plates through the deep aseismic creeping as well as episodic earthquakes or creeping in more layers shallow. Several previous GPS studies in the Java Island region were conducted by focusing in a localized deformation study located around the main fault region. Information on the near-surface fault in East Java (Kendeng Zone) is the reason for obtaining geometry information and the location of the fault in the deeper zone so that this information can add data on the earthquake potential in Java for mitigation actions and spatial interests. This research is expected to produce comprehensive and more detailed information about the process of deformation of East Java’s subsurface structure from Northern to Southern region with Magnetotelurics Method (MT).

Summary Traditional geotechnical approach for identifying basement soil in construction usually done by using borehole method such as Standart Penetration Test (SPT). SPT measures the soil strength by counting the number of blow of the device for a standart penetration to happen. SPT method is very useful in general for measuring the soil strength of a point, but it faces some disadvantages and difficulties. So, thisresearch correlate the N-SPT and Transverse Resistivity of two borehole and two VES data obtained in Gunung Anyar Regency, Surabaya. The correlation shows a minimal error with correlation value of 0.9008 and 0.8199. This results may help further research for consideration of VES substituting traditional SPT method for geotechnical application.

Kabupaten Lumajang merupakan wilayah yang rentan terhadap tsunami karena berbatasan langsung dengan Pantai Selatan yang menjadi pusat gempa bumi serta keadaan pesisir pantai selatan Lumajang yang memiliki tingkat kepadatan penduduk dan pemukiman, aktivitas pemerintahan dan perekonomian yang tinggi. Pemetaan tingkat kerentanan tsunami perlu dilakukan sebagai informasi mitigasi dan rencana tata ruang wilayah. Lokasi penelitian adalah 5 (lima) kecamatan di pesisir Pantai Selatan Lumajang yaitu Yosowilangun, Kunir, Tempeh, Pasirian, dan Tempursari. Tujuan penelitian ini adalah membuat peta kerentanan tsunami Kabupaten Lumajang menggunakan Sistem Informasi Geografis (SIG). Pendekatan variabel kerentanan meliputi elevasi daratan, kemiringan, morfometri pantai, penggunaan lahan, jarak dari pantai dan jarak dari sungai. Metodologi penelitian antara lain pengumpulan data primer dan sekunder, pengolahan data parameter yang mewakili tiap variabel kerentanan serta pemberian bobot dan skor. Hasil kajian ini menghasilkan peta-peta variabel kerentanan wilayah penelitian yang selanjutnya dapat digunakan untuk kebijakan pemerintah daerah dan tindakan mitigasi seperti pemetaan tingkat risiko tsunami.

Study on water balance in a small island is essential to be conducted. A small island normally has small catchment areas so that most of the surface rain water flows quickly into the sea. Consequently, it causes limited recharge of rainwater into groundwater. When the usage of groundwater is high, the water demand-supply could be unbalance. It will certainly cause problems, such as seawater intrusion or water crisis. There are numbers of small islands in Indonesia; in most of these islands, the water balance has not been studied yet. This paper discusses water balance in Poteran- a small island in East Java, Indonesia. The island area is only 49.8 km 2 with population of nearly 50,000 people. The land use in the island is dominated by agricultural areas. In this study, some investigations are conducted including survey of land-surface area, collecting meteorology and climatology data. Thornthwaite approach is used for computing evapotranspiration in water balanced calculation. The results show soil texture dominant is clay loam, with a land use is corn farming (root depth is 0.8 meters), field capacity is estimated 0.25 and permanent wilting point values is 0.12. Precipitation is 1790 mm, the potential evapotranspiration is 2047 mm, water surplus is 300 mm and water deficit is 557 mm a year. The results suggest that the Poteran Island has limited recharge water that could be lead to a water crisis in the future.

Indonesia lied among the three of world major plates so that several districts along the southern coast of Java Island were vulnerabled to the tsunami including Lumajang. South coast of Lumajang had high population density and settlements and high levels of government and economic activity. Therefore, it is necessary to know the level of insecurity and vulnerability to the tsunami in order to be utilized as input of mitigation data for the preparation of regional spatial plans (RTRW) based on tsunami risk level. The objective of this research is to arrange the regional risk map for tsunami in Lumajang Regency using Geographic Information System (GIS) through approach of insecurity and vulnerability analysis of tsunami. The insecurity rate is analyzed based on seismicity map and run-up data of tsunami event in Lumajang District. Vulnerability approach used multicriteria such as land elevation, slope, coastal morphometry, land use, distance from the coast and distance from the river. The methodology that was used included data collections of both primary and secondary data such as satellite imagery of earth map, Lumajang statistical data. Each vulnerability data variable was processed to result a weighting and scores that its become the parameters for making a regional tsunami vulnerability map. The results showed three level of risks in five subdistricts that directly adjacent to the Southern Coast such as Yosowilangun, Kunir, Tempeh, Pasirian, and Tempursari. The high tsunami risk which covered almost along the coast, the ramps morphology, without any protective vegetation and human activities at the site while the medium of tsunami risk which were in areas with elevation more higher than the coastal and the low of tsunami risk had variations of topography, quite far from the coast and less human activities.

Salah satu metode geofisika yang dapat digunakan untuk memodelkan fitur geologi dalam, seperti subduksi, adalah metode gaya berat. Terdapat korelasi yang bersifat kuantitatif antara data gaya berat dan model geologi subduksi. Penelitian ini mengamati pengaruh bentukan dan persebaran densitas dari model geologi subduksi terhadap bentukan dan besar nilai data gaya berat, atau yang biasa disebut dengan forward modelling . Tujuan dari penelitian ini adalah untuk mengkarakterisasi efek yang muncul pada data gaya berat akibat dari bentuk model geologi subduksi di Pulau Jawa. Hasil yang didapatkan menunjukkan bahwa bentukan model subduksi yang sangat berpengaruh terhadap bentuk data gaya berat ,dengan jarak antar titik sejauh satu kilometer, hanyalah model dengan kedalaman 0 hingga 15 kilometer. Model subduksi pada kedalaman 15 hingga dasar model hanya memengaruhi kecenderungan atau kemiringan profil data gaya berat.

Lapangan Teapot Dome, Wyoming terletak di Powder Basin yang merupakan cekugan prospek hidrokarbon. Data yang digunakan pada penelitian ini yaitu data seismik 3D Post Stack dan 7 data sumur. Zona target terletak pada F1WC dan Redpeak. Zona target memiliki litologi berupa sand dan shaly sand. Dilakukan karakterisasi reservoar pada kedua zona target guna mengevaluasi zona. Kedua data diintegrasi menggunakan metode inversi berbasis model dan metode seismik multiatribut. Metode inversi berbasis model dilakukan guna memprediksi impedansi akustik. Metode seismik multiatribut menggunakan lebih dari satu atribut untuk memprediksi parameter sumur. Parameter yang dicari pada penelitian ini yaitu porositas sehingga didapat persebaran porositas dalam volume seismik. Digunakan pula metode Probabilistic Neural Network guna meningkatkan hasil korelasi antara data seismik dengan data sumur saat memprediksi porositas. Berdasarkan hasil yang didapatkan diketahui bahwa karakter reservoar zona F1WC yaitu impedansi akustik pada rentang 27000-34000 (ft/s)(gr/cc) dan porositas 8-11%. Sedangkan untuk zona RDPK mempunyai rentang nilai impedansi akustik 34000-49000 (ft/s)(gr/cc) dan porositas 5-10%. Berdasarkan justifikasi karakter log, inversi, dan multiatribut diketahui bahwa kedua zona target merupakan zona prospek hidrokarbon.

Salah satu penyebab terjadinya tanah longsor yaitu adanya zona water content atau zona tersaturasi air dimana terdapat kondisi terakumulasinya air pada suatu lapisan tanah yang sukar meloloskan air. Kondisi tersebut dapat diketahui dengan metode geolistrik resistivitas dengan konfigurasi Wenner-Schlumberger karena dapat menerjemahkan kondisi bawah permukaan secara horizontal maupun lateral dengan baik berdasarkan nilai resistivitas. Nilai zona water content yang terlihat yaitu antara 4,39 – 9,29 Ωm. Berdasarkan peta rawan bencana yang telah dibuat, faktor penyebab terjadinya tanah longsor adalah curah hujan, tutupan lahan, dan kelerengan. Hasil pemetaan yang telah dilakukan menunjukkan bahwa Kecamatan Selorejo merupakan salah satu daerah yang kerawanan longsornya bernilai sedang, yakni diantara 24,03.

Untuk melakukan prediksi sebaran litologi suatu reservoir, dapat dianalisis melalui nilai impedansi akustik dari tiap batuan, dikarenakan tiap bnatuan akan memiliki nilai impedansi akustik yang berbeda ketika berbeda jenis litologi. Dengan adanya data seismik, data sumur, serta data pendukung lainnya, kita dapat memperoleh informasi kondisi bawah permukaan secara detail. Penelitian kali ini bertujuan untuk memprediksi sebaran reservoir batu pasir Dakota pada lapangan Teapot, hak milik RMOTC dan U.S.Department of Energy, berdasarkan pada parameter impedansi akustik dari masing-masing batuan. Metode yang digunakan pada penelitian kali ini adalah menggunakan inversi berbasis model. Hasil yang didapat merupakan sebaran litologi batupasir formasi Dakota, disajikan dalam bentuk peta impedansi akustik. Berdasarkan hasil inversi seismik, diketahui lokasi rekomendasi yang memilki litologi batu pasir baik sebagai reservoir adalah daerah dengan nilai impedansi relative lebih rendah, dengan range nilai 27.000 ft/s*g/cc – 29.000 ft/s*g/cc, dan berarda pada lokasi tengah menuju ke selatan dari daerah penelitian.

Salah satu penyebab munculnya semburan lumpur Sidoarjo yang masih diperdebatkan hingga saat ini yaitu mengenai reaktivasi patahan watukosek. Studi yang telah dilakukan sebelumnya menunjukkan adanya manifestasi di permukaan akibat patahan watukosek, contohnya Tebing Watukosek dan pembelokan geomorfologi Kali Porong. Penelitian dengan menggunakan metode tahanan jenis dilakukan untuk memetakan patahan yang berada di daerah Kali Porong dan Patahan Watukosek. Lintasan yang digunakan memiliki bentangan 400m dengan arah Barat – Timur untuk memotong patahan yang berarah Barat Daya – Timur Laut dari Gunung Penanggungan menuju semburan lumpur Sidoarjo. Kedalaman pengukuran mencapai ±74.8m dengan anomali tahanan jenis terendah 1.05 Ohm.m hingga yang tertinggi 33.3 Ohm.m.

Jambi Province has an extraordinary treasure of Genetic Resources. This fact is supported by geographic conditions and supported by four national parks. Jambi Province has supported the use and protection of genetic resources, one of its efforts is to establish a Regional Commission on Genetic Resources. As a chief executive of the daily implementation of this commission, Research and Regional Development Board (Balitbangda) through its duty conducting study and research activities because if not managed well so the availability of genetic resources be threatened. This study aims to determine the role of Balitbangda of Jambi Province to preserve the genetic resources in Jambi Province. This research is qualitative research with a phenomenological approach. This research was carried out at Balitbangda Jambi as a chief executive of the daily implementation of The Regional Commission in Jambi Province. The sampling technique using purposive random sampling and types of data used are primary and secondary data collected by in-depth interviews and document searches. The results showed that the role of Balitbangda in Jambi Province in its efforts to preserve genetic resources were conducting research and development activities, active in the Regional Commission of Genetic Resources, cooperated with competent institutions, conducted seminars on the results of studies, socialized to teachers/education staff in the district/city about the genetic resources, and supported the acceleration of registration of geographical indications of Pineapple Tangkit Baru. The roles were still not optimal because there are still obstacles in the implementation.

The southern part of Java Island is located between the two plates of the subduction zone, therefore this region had an active tectonic and volcanic activities. Those made a deformation of the geology around the southern part of Java island. This research was conducted to know the volume of deep geological structures to provide an overview of disaster warning systems in southern East Java region. The research that has been carried out using numerous active geophysical methods such as seismic methods had not been able to indicate internal structures. The needed for innovation used the integration of gravity and magnetotellurics methods. Bouguer anomaly gravity map became the supported data for interpretation. It showed low-density zones (0-80 mGal) between Pacitan-Trenggalek and beneath the Lumajang area which indicates the fault structure. Magnetotellurics (MT) which had a high penetration so that it is able to map deep active geological structures below the surface. The research area covered 8 regencies at the southern of East Java namely Pacitan, Trenggalek, Tulungagung, Blitar, Malang, Lumajang, Jember, and Banyuwangi. Magnetotelluric 1D processing showed indications of faults with orientations tend to be NE-SW between Pacitan and Trenggalek with depth (500 m – 8000 meter). Indications of faults with orientation tend to be NorthEast-SouthWest in Lumajang (100 - 500 meter).

Gravity survey plays an important role in early stage of subsurface imaging in geothermal system. The aim of this study is to understand the subsurface structure and possibly the heat source based on rock density distribution with three dimensional inversion modeling (3D). In 2010, Center of Mineral Resources, Coal and Geothermal of Indonesia was performed gravity survey at Lili Sepporaki geothermal area with 205 stations within a 10 x 10 km coverage area. The complete Bouguer anomaly was obtained with the density of 2.8 g/cm3 and this density was used to do 3D modelling. Bouguer anomalies ranging from 40 mgal to 62 mgal were observed in the study area with low anomalies values located in the northern part and high anomalies located in the southern part of the study area. Based on the 3D inversion modeling results, there are low density rocks with values between 2.0 - 2.3 g/cm3 around the hot springs of the research area with a depth of 2 km. This rocks are interpreted as intrusive igneous rocks and are thought as the heat source of geothermal systems in the study area.

Measurements of the 3D resistivity method have been carried out in the Terung Site, Terung Wetan Village, Krian, Sidoarjo Regency. The study was conducted to determine the distribution pattern of the Terung Site subsurface structure. Many archaeological sites from ancient times have been buried or deliberately buried beneath the surface. The process of searching archaeological sites that have been carried out only based on the results of stories that developed in the community. The 3D resistivity method can be used as a method for conducting site searches. The 3D resistivity method gives the image of the resistivity distribution in a vertical and horizontal cross section therefore to produce a more resolutive image. Based on measurements with the 3D Wenner configuration resistivity method, there is a structured continuity of Kadipaten Terung Site in the depth of 1.5-3.5 meters with resistivity values of 30 Ωm - 80 Ωm.

Penelitian menggunakan metode inversi post-stack dan geostatistik telah dilakukan pada Formasi Lakota Lapangan Teapot Dome, Wyoming, Amerika Serikat. Tujuan dilakukannya penelitian ini adalah untuk mengkarakterisasi reservoar Batupasir Formasi Lakota, hak milik RMOTC dan U.S.Department of Energy. Metode yang digunakan pada penelitian ini adalah inversi post-stack metode modelbased untuk mendapatkan nilai AI dari volume seismik dan aplikasi geostatistik menggunakan analisis variogram, Kriging with External Drift dan Simulasi Gaussian bertujuan untuk mendapatkan distribusi sifat fisis reservoar secara lateral dari data sumur. Hasil inversi modelbased menunjukkan nilai impedansi Formasi Lakota berada pada rentang 28000-36000 ft/s*g/cc yang mengindikasikan bahwa Formasi Lakota merupakan interbedded shaly sand. Pembuatan layering reservoar dari volume AI menjadi empat map bertujuan untuk mendapatkan persebaran sifat fisis reservoar yang lebih akurat menggunakan metode geostatistik. Hasil dari metode geostatistik menghasilkan nilai porositas total berada pada rentang 20 – 30 % dan Vshale memiliki rentang nilai 10 – 40 % pada keempat layer map tersebar pada daerah Barat Laut yang termasuk ke dalam zona tight (nilai AI > 30000 ft*s/g*cc). Daerah tersebut diindikasikan sebagai area yang berprospek dan rentang nilai sifat fisis tersebut diklasifikasikan sebagai karakteristik reservoar yang baik. Reservoar batupasir yang tersturasi gas berlokasi di sekitar sesar normal dengan orientasi Timur Laut – Barat Daya, yang dapat ditunjukkan dengan bright amplitude pada data seismik dan nilai impedansi rendah. Dua sesar normal mayor berorientasi Timur Laut – Barat Daya membentuk two way dip closure trap berpreran sebagai jebakan hidrokarbon gas pada Formasi Lakota yang telah terbukti dengan adanya sumur produksi 41-2-X-3, 53-LX-3 dan 56-LX-10 berdasarkan data produksi Lapangan Teapot.Kata Kunci: Formasi Lakota, Geostatistik, Inversi Post-stack, Shaly-sandThe research using post-stack inversion and geostatistical method has been conducted on Lakota Formation, Teapot Dome Field, Wyoming, USA. The aim is to obtain reservoir characteristics and physical properties of Lakota Sandstone, copyrights of RMOTC, U.S Department of Energy. The method used in this research consist of Post-stack inversion modelbased method to obtain Acoustic Impedance of seismic volume and geostastical method using variogram analysis, Kriging with External Drift and also Gaussian simulation to obtain physical properties distribution laterally from well data. The result of modelbased inversion shows the impedance value of Lakota Formation has the range 28000-36000 ft/s*g/cc. It indicates that Lakota Formation has interbedded shaly-sand characteristics. The inversion result is divided into four layers and sliced into four maps to obtain physical properties distributin of Lakota Formation more accurately. The result of geostatistical method yields Total Porosity value of four maps on Lakota Formation has 20 – 30 % and Vshale 10 – 40% scattered in Northwest area of Teapot Field represents a tight zone (Acoustic Impedance value > 30000 ft/s*g/cc), which is indicated as prospective area and also those physical properties values classified as good reservoar characteristics. Sandstone reservoir which saturated by gas is located around normal fault with Northeast – Southwest orientation. It can be seen by bright amplitude on seismic data and low impedance value. Two major normal fault with Northeast – Southwest orientation forming two way dip closure trap has the role of gas brine zone trap of Lakota Formation. The existing of gas zone was proven by production wells 41-2-X-3, 53-LX-3 dan 56-LX-10 from Teapot Production Data.Keywords: Geostatistics, Lakota Formation, Post-stack Inversion, Shaly-sand

Hazardous waste is a waste with properties which can pollute and damage the environment, human health, and other living things. Lakardowo is a village that is suspected of being contamination by hazardous waste derived from industrial activities. Measurements with the VLF-EM and Resistivity method were used in this study. In addition, ground water level mapping and soil sampling in locations around the industry were conducted for the XRF test. Groundwater mapping results show that groundwater flow lead to the Northeast-South and Southwest of the industrial site. The soil samples that have been tested by XRF show the presence of heavy metals, wherein hazardous wastes generally contain various types of heavy metals that are conductive or have low resistivity values. Quantitative interpretation of VLF-EM data shows the presence of low resistivity anomalies at several measurement sites, which are suspected to have been contaminated with soil by waste. Resistivity data processing results, showing a low resistivity anomaly (≤ 3 Ω.m) located to the north (near an industrial site) and spreading towards the southwest along the measurement path. The result of a combination of quantitative interpretations of both methods, obtained, the direction of anomalous flow of hazardous waste moves southeastward and towards deeper soil coating following the direction of rock coating.

Sebuah kawasan yang memiliki aktivitas vulkanik, mempunyai potensi SDA yang dapat dimanfaatkan sebagai sumber energi panas bumi hingga cadangan hidrokarbon. Tujuan dari penelitian ini ialah untuk mengkarakterisasi fisis dan analisa hubungan antara parameter densitas, kecepatan Vp, atenuasi, dan resistivitas pada batuan vulkanik studi kasus Gunung Arjuno-Welirang. Penelitian diawali dengan pengambilan sampel di lapangan dan pembuatan coring batuan sehingga didapatkan 45 coring batuan, dari 16 sampel batuan, yang mewakili 6 satuan batuan, kemudian dilakukan pengukuran parameter resistivitas dengan metode konfigurasi axial resistivity, pengukuran densitas dengan prinsip Archimedes, dan pengukuran kecepatan Vp serta atenuasi dengan transmisi gelombang ultrasonik. Maka didapatkan hasil rentang parameter densitas batuan vulkanik Arjuno Welirang berkisar antar 2400 – 2900 kg/m3, sedangkan rentang resistivitas bervariasi dari 30-185 kOhm.m, kemudian rentang nilai kecepatan Vp bervariasi dari 5100-6700 m/s, dengan koefisien atenuasinya memiliki rentang 0.05–0.23x10-3dB/m, dimana nilai densitas akan berbanding lurus dengan kecepatan Vp, dan nilai resistivitas akan berbanding terbalik dengan densitas-kecepatan Vp. Berdasarkan analisa petrologi batuan vulkanik Arjuno-Welirang memiliki tipe intermediate-mafik dengan nama batuan dominasi andesit-basaltik dan basalt.

The existence of mud volcano system in East Java is known from the ancient period, especially in Surabaya. Gunung Anyar mud volcano is one of the mud volcano system manifestation was appeared close to the residence. Because of this phenomenon we have to learn about the impact of this mud volcano manifestation to the neighbourhood. The microtremor study was conducted to evaluate the possible influence effect of the mud volcano to the environment and get more information about the subsurface condition in this area. Microtremor is one of the geophysical methods which measure the natural tremor or vibration of the earth, the dominant frequency of the tremor represent thickness of the soft sediment layer overlay above the bed rock or harder rock layer beneath our feet. In this study 90 stations was measured to record the natural tremor. The result from this study shows the direct influenced area of this small mud volcano system is close to 50m from the centre of the mud volcano and bed rock of this area is range between 66 to 140 meter.

Daerah penelitian ini beririsan dengan peta Cekungan Air Tanah (CAT) Palu yang merupakan gabungan beberapa akuifer. Digunakan Vertical Electrical Sounding (VES) yang merupakan penggambaran sebaran nilai lapisan resistivitas secara vertikal 1 dimensi. Penelitian ini menggunakan konfigurasi schlumberger pada daerah penelitian dengan 12 titik ukur VES (VES1 – VES12). Hasil pengolahan VES dimodelkan 3 dimensi, selanjutnya dikorelasikan dengan peta CAT Palu untuk determinasi zona yang berpotensi sebagai akuifer. Geologi daerah penelitian terdiri dari Qap dan QTms yang masing-masing memiliki komponen pasir yang dapat berpotensi sebagai akuifer. Hasil pengukuran VES menunjukan sebaran nilai resistivitas sebesar 13 s.d. 1202 Ohm.m. Nilai resistivitas 20-120 Ohm.m merupakan zona interest yang diduga sebagai litologi batu pasir atau endapan pasir. Titik pengukuran yang terkorelasi dengan CAT Palu terdiri dari titik VES3, VES4, VES6, dan VES8 memiliki lapisan yang berpotensi lebih kuat sebagai akuifer dengan rentang kedalaman masing-masing 4,5-58,2 m; 8,7-36,3 m; 3,6-97,5 m; dan 33,2-99,2 m. Penentuan daerah resapan air dilakukan dengan analisis topografi, dihasilkan area tersebut berada pada timur laut daerah penelitian dengan rentang elevasi 1400 s.d. 300 m. Pada daerah penelitian telah ditunjukkan potensi zona akuifer dengan tanda resistivitas yang cenderung lebih rendah dan litologi batu pasir atau endapan pasir yang memungkinkan adanya aliran fluida. Masalah ketersediaan air tanah diduga berkaitan dengan Masalah ketersediaan air tanah diduga berkaitan dengan kemampuan saturasi batuan

Kecepatan gelombang kompresional batuan dapat diketahui melalui pengukuran secara langsung atau melalui prediksi secara matematis menggunakan parameter lain. Tujuan dari penelitian ini adalah untuk memperoleh kecepatan gelombang kompresional teoritik Vhitung pada batuan vulkanik berdasarkan komposisi mineralogi, memperoleh nilai kecepatan gelombang kompresional hasil pengukuran Vukur pada batuan vulkanik, serta membandingkan nilai Vhitung dengan Vukur. Penelitian ini dilakukan terhadap 20 core batuan vulkanik kompleks gunungapi Arjuno-Welirang yang memiliki struktur masif dengan komposisi basaltik hingga andesitik. Seluruh core dikelompokkan berdasarkan kesamaan petrologi menjadi enam kelompok sampel. Sebuah sayatan tipis diekstrak dari setiap kelompok sampel untuk keperluan kalkulasi Vhitung. Vhitung diperoleh menggunakan pendekatan Voigt-Reuss Bounds dengan parameter input modulus elastik (K; μ), densitas, dan persentase mineral konstituen. Komposisi mineral pada sampel diidentifikasi melalui analisis sayatan tipis menggunakan mikroskop polarisasi dan perangkat lunak pengolahan citra Jmicrovision. Vukur diperoleh dengan uji kecepatan pulsa ultrasonik. Rentang nilai Vhitung yang diperoleh adalah 6082.37 - 6417.21 ms -1 . Rentang nilai Vukur yang diperoleh adalah 3708.14 - 4950.45 ms - 1 . Nilai Vhitung dan Vukur yang tidak proporsional disebabkan oleh diterapkannya berbagai asumsi yang muncul pada proses identifikasi mineral kedalam kalkulasi Vhitung. Asumsi-asumsi tersebut menyebabkan nilai Vhitung yang diperoleh tidak mendekati kondisi ideal sebagaimana pada Vukur

Jawa timur bagian utara merupakan daerah prospek dalam industri Minyak dan Gas Bumi. Sebagai zona RMKS (Rembang, Madura, Kangean, dan Subala). Cekungan Jawa Timur utara memiliki kerangka geologi didominasi oleh graben, half-graben, dan sesar lain akibat fase rifting pada periode ekstensional zaman Paleogen dan arah sedimentasi berawal sisi utara cekungan, seiring terbentuknya gunung api hasil subduksi lempeng dibagian selatan maka sedimen terendapkan dari bagian selatan cekungan. Secara regional terdapat potensi reservoar yang terbentuk dari batuan pasir dan karbonat. Berlatarbelakang sumur tua yang terletak di desa Sumberwaru, Kecamatan Wringinanom, Gresik. Indikasi awal daerah tersebut memiliki petroleum system sehingga, penelitian bertujuan mengidentifikasi arah persebaran sedimen dalam tinjauan awal eksplorasi kembali pada daerah tersebut. Data yang digunakan adalah data primer pengukuran metode mikrotremor berdimensi 36.000 m 2 (122 titik) selama 6 hari, dengan frekuensi natural 4-8 Hz.

Peristiwa gempa bumi dan Tsunami merupakan bencana yang tidak bisa dihindari oleh masyarakat Indonesia sebagai negara yang terletak pada jalur tektonik aktif dunia. Akibat adanya pertemuan lempeng Indo-Australia pada daerah bagian Selatan Indonesia, menyebabkan kawasan ini memiliki nilai seismitas yang cukup tinggi. Salah satu kawasan yang sering terjadi peristiwa gempa dan Tsunami yaitu berada di jalur subduksi Sunda. Pada kawasan ini, terjadi beda densitas subduksi antara Pulau Jawa dan Pulau Sumatera akibat adanya perbedaan gaya kompresi pada kedua kawasan tersebut. Perbedaan densitas subduksi diketahui dari inversi data anomali gravitasi pada jalur subduksi Sunda untuk mengintepretasikan struktur regional pada area yang pernah terjadi gempa besar yang menyebabkan Tsunami. Setelah dilakukan inversi 2D terhadap data gravity pada tujuh lintasan yang searah dengan arah subduksi di jalur Sunda, dimana line 4 di daerah Jawa dan line 5 sampai 7 di daerah Sumatera. Didapatkan beda densitas pada line 1 sebesar -0.24 ~ -0.26 g/cm3; line 2 sebesar -0.25 ~ -0.5 g/cm3 ; line 3 sebesar -0.3 ~ -0.5 g/cm3 ; line 4 sebesar -0.19 ~ -0.24 g/cm3 ; line 5 sebesar -0.3 ~ -0.55 g/cm3 ; line 6 sebesar -0.1 ~ -0.26 g/cm3 dan line 7 sebesar -0.05 ~ -0.2 g/cm3. Berdasarkan beda densitas ini, diketahui bahwa daerah Jawa memiliki beda densitas lebih besar karena laju subduksi lebih tinggi dibandingkan daerah Sumatera.