bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of the distribution of flood area in Karawang Regency using SAR Sentinel 1A image
Authors: Dyah Sukowati Kusumaning Ayu , Kusratmoko E 
Published: August 2019

Abstract
Flood is one of the most frequent hydrometeorological disasters compared to other disasters. Floods cause more damage than other disasters. Karawang regency is one of the areas prone to national floods, due to floods that often hit the region. Detection of flood areas can be determined using multitemporal SAR Sentinel 1A image. Several factors can affect the occurrence of floods. The weighted index overlay analysis of each variable with the scoring method was done to construct a prediction model of flood hazard prone locations. Logistic regression analysis is used to analyze the variables that have the most significant effect on flood potential in Karawang. The result of analysis shows that flooding variable has significant correlation with the occurrence of flood inundation. Rainfall is the dominant factor of flood incident in Karawang regency that is in the class of 1500 - 2000 mm/yr, on the slope <2% and the type of flat entisol soil and the use of settlement land and rice field. The area is very vulnerable in the western part of central Karawang is a rice field area and close to the river flow in the District Rengasdengkol, Telukjambe Barat and Timur
Identification of fractured-basement reservoir based on integration of FMI Log and seismic attributes in hydrocarbon field “I”, Barito Basin, South Kalimantan
Authors: Halimatussa’diyah Nyiayu , Syamsu Rosid Mohammad , Indrajaya Helmi 
Published: August 2019

Abstract
As basement has very small matrix porosity, secondary porosity is needed to store hydrocarbon within the basement. Fracture is a secondary porosity, yet not all fracture can be a good secondary porosity. Open fractures have capability to store hydrocabon, also have important roles in productivity and quality of the pre-tertiary basement reservoir. This study is aimed to identify open fractures using FMI log and seismic attributes in the Field “I”, Barito Basin. Interpreted image log (FMI) on two wells gives the azimuth and dip orientation of open fractures are ENE –WSW, NNW-SSE and WNW-ESE and also the horizontal stress orientation. The stress orientation from image log combined with leak-off test (LOT) data and density log used to identify stress fields. Azimuth and dip orientation of the open fracture from FMI log is the input of the stereonet, as an orientation filter for ant-tracking. Ant-track attribute is based on ant-colony optimization algorithm that captures only continuous features and used as edge enhancement methods for fracture-sensitive attributes. Variance is a fracture-sensitive attribute that applied as input data for ant-track algorithm. The results of ant-track map are well correlated and confirmed by image log analysis. Also, by applying ant-track attribute to the fracture-sensitive attributes succesfully able to identify faults and fractures with better resolution and visualization than only using the fracture-sensitive attribute itself, so it makes easier to interpret and get the information.
Bayesian Inversion for Layered Spherical Symmetric Earth Conductivity Model from Global Magnetic Data
Authors: Grandis H , Tarits P 
Published: August 2019

Abstract
In the Bayesian perspective, inference on model parameters from observed data is performed by calculating the likelihood of the data given prior model parameters, i.e. to estimate the posterior probability of model parameters. With the advent of computational resources, there are increasing interests in resolving full non-linear inverse problems using global approach. Although the current trends are geared towards algorithms to efficiently explore the model space, we employed the classical “pure” Monte Carlo method to resolve the inverse problem in the global scale induction study. Observatory and satellite magnetic data are used to provide insight on the deep mantle conductivity. In this case, layered (1D) spherical symmetric conductivity model can be considered as adequate to represent the Earth’s conductivity variation with depth. Model parameters (resistivities and thicknesses) with uniform probabilities over predefined intervals are drawn as samples of the model space. Reliable posterior estimates are derived from a large number of samples which are still manageable with the current PC technology. Relatively small uncertainties of the posterior estimates suggest that the Monte Carlo method is adequately sampled the model space with a small number of model parameters. Our results are consistent with a monotonic increase of conductivity with depth with a marked inflexion at about 700-900 km, while discontinuities at 410 km and 660 km known from seismic and petrology data seem unresovable directly from EM data.
Preliminary Gravity Study of Pre-Tertiary and Tertiary Rock in Northern Kebumen, Central Java, Indonesia
Authors: Nizar Ahmady Faridz , Santoso Djoko 
Published: August 2019

Abstract
Luk Ulo Melange Complex is a Pre-Tertiary rock formation consisting of various lithological background and complicated geological structure. Located in Northern Kebumen Regency, this rock is originally interpreted as products of tectonic process caused by paleo-subduction between Indian Oceanic Plate beneath Eurasian Plate in Cretaceous age. According to previous study on geological surface investigation shows that the melange complex is tectonically overlain by Tertiary sedimentary formation. On the contrary, geophysical study of the subsurface condition of the area is still under discussion due to limited of measured data. In order to obtain detailed subsurface image, gravity profiling was measured and interpreted across both Tertiary and pre-Tertiary rock. Frequency domain filter and designed moving average filter were used to separate residual and regional anomaly. The results denote gravity value of residual anomaly varying from -5 to +5 mGal, while regional anomaly is ranging from 150-180 mGal respectively. The preliminary interpretation was developed by taking into account the geological information and also the data that was collected during field campaign. Overall, high gravity anomaly is interpreted as diabase intrusion in the middle of research area. Meanwhile, low gravity anomaly indicated clay rich rock material related to matrix content of Luk-Ulo Melange Complex in the northern area.
Impact of The 2004 Sumatra-Andaman Earthquake to The Stress Heterogeneity and Seismicity Pattern in Nothern Sumatra, Indonesia
Authors: Taufiq Rafie Muhammad , Sahara David P , Widiyantoro Sri , Dian Nugraha Andri 
Published: August 2019

Abstract
Sumatra Island is a highly seismic active region due to its close location to the convergent zone between the Indo-Australian and Eurasian plates, and the existence of the Great Sumatran Fault (GSF). These conditions caused the island of Sumatra suffered from hundreds of earthquakes with Mw > 4 per year. Particularly, a 9.0 Mw Sumatra-Andaman 2004 earthquake occured in northern Sumatra which changed the in-situ stress and seismicity pattern. In such case, quantifying the tectonic stress perturbation prior and after 2004 Sumatra-Andaman earthquake is becoming key issue in assessing the seismic hazard. To invert the in-situ stress information in Sumatra, first we identify the fault plane from its auxiliary plane in the focal mechanism solutions using the fault instability criterion. There are 354 focal mechanisms data of earthquake with Mw > 5 and focal depths < 250 km along northern Sumatra Island from 1976 to 2010. This catalogue was compiled by combining the data from Global Centroid Moment Tensor (GCMT) catalogue and the International Seismological Centre (ISC) bulletin. We then divided the focal mechanism catalogue into two parts, i.e. prior and after Sumatra-Andaman 2004 earthquake. An iterative joint inversion is then implemented to estimate the in-situ stress orientation and its magnitude ratio. The in-situ principal stress orientation and magnitude ratio obtained from this study will be used to build a Sumatran stress map and its correlation with the seismicity pattern variations in the region. Our results produce remarkable changes of maximum principal stress orientation after 2004 megathrust earthquakes along the region. As the seismic hazard potential is controlled by stress concentration, the obtained results from this study could also be used further for seismic hazard mitigation in northern Sumatra.
Near-surface S-wave Estimation base on Inversion of Rayleigh Wave Dispersion Curve Using Genetic Algorithm
Authors: Rubaiyn Al , Priyono Awali , Yudistira Tedi 
Published: August 2019

Abstract
Multi-channel analysis of surface wave (MASW) is a suitable technique to infer shallow structure of vertical shear-wave velocity profile from seismic record data. The processing stage is focused on obtaining the reliable dispersion curves, and the final stage of the method is that to obtain the shear velocity model that can explain the observation. The genetic algorithm (GA) method, one of the global optimization approaches, has been implemented to obtain shear wave model from Rayleigh wave dispersion curve. The GA method mimic biological evolution in order to obtain the optimum solution. Application of GA method to two synthetic models for normal velocity profile and low velocity anomaly give good results indicated with small misfit. Finally, we demonstrate the GA to Rayleigh dispersion curve for real data which calculated by using phase-shift method.
Processing and data analysis of time-lapse microgravity due to ground water level changing in baseline stage of CO2 injection
Authors: Darmawan Noviandi , Wahyudi E J , Kadir W G A , Sule R 
Published: August 2019

Abstract
Monitoring stability of the field in research area using time-lapse microgravity method has been done with data acquisition process in 2014 and 2016. This method requires high accuracy in µGal units. Since we use relative gravimeter, drift performance from instrument is also influential to the data significantly. In this paper we conducted reprocessing data using closer reference station from research area thus the drift effect cause by mobilitation time and duration of instrumental resting can be reduced. In conditions prior to injection, ideally the change in gravity value in the area would be very small with the assumption of the absence of injection activity. However, after the processing data stage we can see time-lapse microgravity anomalies within the range of ± 80 µGal. This anomaly was assumed occurred by instrument effect (typical for spring sensors) in field measurement and shallow hidrology effect (ground water level change). From the gravity surveys in 2014 and 2016, there is big difference in long term drift between 2014 and 2016 data, which is 2014 has average value of 320 µGal/day and 2016 has average value of 120 µGal/day. Other than that, in repeatability test, 2014 has 54% and 2016 has 77% from total data that is within the range of deviation ± 10 µGal (repeatability value in accuracy of ideal Scintrex CG-5). Analysis of gravity data measured in three benchmark (BM) was also performed to know the gravity variation rate in research area.
Lindu Software: An Open Source Seismological Data Processing Using Python Framework To Relocate Hypocenter (Preliminary Software)
Authors: Pradnya Andika Putu , Styawan Yudha , Suhendi Cahli , Firdaus Ruhul 
Published: August 2019

Abstract
Recorded seismogram of an earthquake data contains the earth structure information. Researchers developed the method to extract the information and derives it into the program codes. However, generally, the program codes developed only for specific function and work on only specific scale. Almost the existing programs have a limitation, for example, they work on command-line based and less user-friendly. Lindu software is developed to solve these problems. In this paper, we show the preliminary results of Lindu software, a GUI – based software which is open source and developed in python platform. This software integrates the common procedure of routine data processing in earthquake seismology and works in local and regional scale. It is designed to read multi-component data on multi-station. To identify events automatically, we employ SL Kurt’s method and use the results as guided auto–picking. However, the picked time also can be changed manually. Furthermore, we employ Joint Hypocenter Determination (JHD) algorithm to locate the hypocenter of earthquake events and update the 1D velocity model simultaneously. Then the events can be relocated by employing the double-difference method. The software was tested on the available data from IRIS and BMKG and shows the acceptable and reliable results.
Determining Source Model and Aftershocks of 2006 Yogyakarta Earthquake, Indonesia using Coulomb Stress Change
Authors: Budiman R , Sahara D P , Nugraha A D 
Published: August 2019

AbstractOn 26 May 2006 at 22:53:59 UTC, an earthquake with moment magnitude of 6.4 occurred in Yogyakarta, Indonesia. The source of the event is still debatable. Some believe the event was caused by the reactivation of the Opak Fault which has a left-lateral type movement. Previous studies indicated there are two possibilities to explain the mechanism of the Yogyakarta earthquake. First is based on the focal mechanism from NIED (National Research Institute for Earth Science and Disaster) Japan which indicated that the event occurred in an oblique reverse slip. This model states that the complex Opak fault is a flower structure (strike-slip) type. Second is based on NEIC (National Earthquake Information Center) US which indicated that the event was caused by a pure strike-slip fault (active Opak fault). The May 26thearthquake triggered many aftershock events around the old Opak fault. The majority of aftershock events on 3-6 June 2006 were located around 5 km east of Opak fault. It has a trendline of N45°E and lies parallel with the Opak fault. We use Coulomb Stress change to determine which type of source model fit better the aftershocks pattern. The target fault for Coulomb Stress analysis is a left lateral pure strike slip with an orientation of N45°E/90°SE.
Study on the Use of Ground-Penetrating Radar Technique to Recognize Tin deposits in Bangka Island
Authors: Parnadi Wahyudi W. , Amin Sarwo S. , Heriawan Mohamad N. , Parnadi Rizandi G. 
Published: August 2019

Abstract
Bangka Island, which is situated in the east of Sumatra, is included in the Indonesian tin belt, spanning from the Malayan Peninsula to the southeast direction until Bangka Island. After ten years of exploitation, intensive exploration to locate new tin deposits is needed to add new tin reserve from available resources. This research is aimed at applying Ground-Penetrating Radar (GPR) technique to recognize tin deposits at some location onshore. GPR method is selected among other geophysical methods due to its potential to image subsurface effectively, both in time and campaign cost. GPR Mala RAMAC system equipped with 100 MHz antenna came to use. Three blocks of 200m x 200m area comprising of around 9 in-line and 9 cross-line profiles were investigated. The acquired data were then processed using careful processing steps, including dewow, Butterworth bandpass as well as f-k filtering to avoid information loss. The processed data were then analyzed by using nine characteristic frequencies which are determined in frequency as well as in time domain. With the aid of borehole log data from all of measurements locations, we recognize specific signature associated with Tin layers at depths of 5 - 10 meters.
Bouguer anomaly comparison using elevation data measured with hand-held device and geodetic GPS in Blora and Pandan Mountain
Authors: Januari Wahyudi Eko , Santoso D , Kadir W G A , Aji W 
Published: August 2019

Abstract
Land gravity measurements for subsurface studies require good accuracy for three-dimensional measurement of station’s coordinate (X, Y, Z). These coordinate data will contribute to calculation of Bouguer anomaly correction in the research area. In this study, we compared the coordinate data measured using hand-held devices and geodetic GPS devices. A more accurate tool is a Trimble R4 geodetic GPS and then we select the acquired data as a reference (Ground Control Points). The hand-held devices that we used are consist of the SUUNTO Escape 203 altimeter and the Garmin GPSMAP 60CSx. The research areas of this studi are in Blora and Pandan Mountain. At that location, we conducted acquisition of elevation data and also gravity. The relative gravimeter used to observe variations of gravity in this study is Scintrex CG5. Gravitational data processing is performed until we obtain Complete Bouguer Anomaly (CBA). The results of this study, we get statistical comparison of the accuracy of elevation data as well as differences in CBA values from the study area. Accuracy of elevation data with hand-held devices based on field measurements in Blora and Mount Pandan reaches 6-53 and 54-95 times lower than a geodetic GPS device. The Bouguer anomaly comparison of the 50 point measurements at the two sites gave the difference range of -1.03 to 2.93 mGal.
Surface Wave Tomography Using Seismic Ambient Noise Data for Subsurface Imaging beneath Bandung Basin, West Java and Its Surrounding
Authors: Dwi Wuryani Sri , Yudistira Tedi , Widiyantoro Sri 
Published: August 2019

Abstract
Seismic interferometry was applied to estimate the shear wave velocity structure beneath the Bandung Basin, West Java. The empirical Green’s function (EGFs) were obtained by cross-correlate each pairs of seismic stations from the temporary seismic network installed in the research area. In this research, we use Rayleigh wave dispersion data as the input for surface wave tomography. The obtained dispersion curves of Rayleigh waves are in the period range 1 - 12 s. The dispersion characteristics of EGFs was also analyzed to estimate the distribution of the ambient noise sources. Based on the symmetricity characteristics of the dispersive signals of EGFs from all two station pairs oriented relatively in N-S and W-E the seismic noise sources was originated from oceanic activity at the Coastline of Java Sea. Furthermore, the dispersion curves also show that the group velocities vary within range of 1.6–2 km/s. The inverted dispersion data into depth models provide the variation of shear velocity structures at depth 1–5 km in the range of 1–2.1 km/s. At depth 1–4 km, there appear high and low velocity contrast in the south of Mt. Tangkuban Perahu, which is may be related to the existence of Lembang Fault. Meanwhile, velocity models at depth 1–3 km show the lateral variation of shear wave’s velocity in the Bandung Basin. The high velocity structures within range 1.8–2.1 km/s lies in the Southwest toward Northeast in the middle of Bandung Basin. This structures divide Bandung Basin into two parts, Western part and Eastern part.
Shear Velocity (VS) Estimation with HVSR (Horizontal to Vertical Spectrum Ratio) Curve Inversion Method of Microtremor Measurement in Bandung Basin
Authors: Luthfiyani N , Yudistira T , Rexha V Ry 
Published: August 2019

Abstract
From the geological aspect, Bandung is a basin surrounded by mountain area. The stratigraphical setting of Bandung is also dominated by thick and soft sediment which makes Bandung needs a mitigation plans needed to reduce the risk of ground motion. Horizontal to Vertical Spectrum Ratio (HVSR) is a popular method developed by (Nakamura, 1989) in microtremor study to use for seismic characterization which is used in this research. This method is used to determine the seismic characteristic in Bandung Basin. The seismic characterization estimated in this research are amplification and dominant frequency. Those values are obtained from HVSR curves which then used to determine the shear wave velocity and depth of Bandung Basin with inversion method. Amplification value in Bandung Basin and its surrounding area is between 2-11.5 with its highest value is in the south-eastern part of observation area. The segmented amplification values based on natural period of building are varies in values based on the range of period and location points. The other seismic characteristic in this research is dominant frequency which value is between 0,1-8 Hz with the highest values are in the north and south part of observation area, while the middle part has the lowest value. Bandung Basin has low shear wave velocity underneath it which less than 800 m/s within depth more than 200 m of depth. There is also a high velocity structure which divide Bandung Basing into two major parts: west part and east part. Those seismic characteristics can be used as a guide to carry-on mitigation procedures to minimize the risk if any disasters happen.
Analysis of Focal Mechanism for Determine Fault Plane Orientation Using The Moment Tensor Inversion Case Study : West Java Geothermal Field
Authors: Sultan Rhamadhana , Rachmat Sule Mohammad , Hendriyana Andri , Supendi Pepen 
Published: August 2019

Abstract
Micro earthquakes in geothermal field is used to monitor subsurface conditions especially in the reservoir. Micro earthquakes data can be used to determine focal mechanism or fault plane solution with moment tensor inversion method using ISOLA program in MATLAB-GUI. Focal mechanism or fault plane solution describes the orientation of the fault and slip on the fault relative to a geographical coordinate system. The arrival time of the P wave from the 3-component seismometer recording is used in moment tensor inversion and the frequency band that used is 0.02 to 0.08 Hz. The result of inversion with minor error indicated by the value of variance reduction approaching 1 calculated is from modelling waveform synthetic with green function and waveform observation. Fault plane solution in the field that represented by beach ball describes the dominant fault in the North is oblique fault with dip 30–90 degree and in the South is reverse fault with dip 20-85 degree.
Evaluation of Continuous Wavelet Transform (CWT) Attribute in Analysis of Gas Reservoir Distribution on Talang Akar Reservoir in “QDR” Field of Northwest Java Basin
Authors: Qodri M N , Mulyani M C , Kaisagara A W , Sukmono S , Ambarsari D S 
Published: August 2019

Abstract
The presence of seismic data as a non-stationary signal is a challenge to be processed with good resolution. Frequency value that change with increasing time make processing in the time domain no longer able to be used optimally, so that a tool is needed to be able to change the domain into the frequency domain. Spectral decomposition with continuous wavelet transform (CWT) method is one of the tools that can be used. The window width used by the CWT method can be applied flexibly with wavelets contained in seismic data and become superior compared to the short time fourier transform (STFT) method. The “QDR” research location in the Talang Akar Formation has a reservoir with a target zone in the form of thin layers (below the thickness of tuning). The purpose of this study was to evaluate how well the CWT method was in mapping the distribution of gas reservoirs at the study areas. The wavelet used in the CWT analysis is a selected Mexican Hat wavelet from two other wavelets (Morlet and Gaussian). The interpretation stage is done by combining CWT maps with log data and TAF 3 and TAF3.2 structural maps. The presence of a gas reservoir can be seen in the CWT section for a frequency of 60 Hz after being validated with log data for the QDR-02 and QDR-04 wells. The frequency value will affect the thickness of the reservoir, the thicker the frequency value will be lower. The distribution of amplitude values for some frequency values at the study location tends to be randomly distributed. So that the CWT method is not good enough to map the distribution of the reservoir in the “QDR” field.