bluuebunny/crossref_metadata_2025_split huggingface dataset:
Physical parameters for the estimation of the return coefficient in the sewer of the La Chivera watershed
Authors: Cely-Calixto N J , Bonilla-Granados C A , Gallardo-Amaya R J 
Published: November 2021

Abstract
Estimating the amount of flow carried by the sanitary sewer system in a locality is essential for the design of new facilities. Having a record of the flow rates allows the adequate hydraulic design of a drainage system. The objective of this work is to determine the physical parameters for the estimation of the return coefficient that allows estimating the flow rates for the sanitary sewer of the La Chivera watershed, San José de Cúcuta, Colombia. In this sense, dry weather monitoring of the wastewater in the study area was carried out. The data collected in the field were used to construct the hourly flow variation curve or inflow hydrograph in the drainage system. The average hourly flow parameters were estimated with a value of 205.7 m3/h, a value recorded at the 11th hour of the day. Similarly, the average daily flow was determined with a value of 180.3 m3/h, while the maximum peak factor was 1.14. Finally, through the physical parameters of the sanitary sewer, the return coefficient was determined, which is 0.72, a value that represents the conditions of the study area.
The 3rd Southeast Asian Conference on Geophysics (SEACG) 2020: Future Challenges and Opportunities in Geophysics (Preface)
Authors: Zulfakriza  , Hendriyana Andri , Saygin Erdinc , Chhun Chanmaly 
Published: November 2021

The issue of IOP Conference Series: Earth and Environmental Science contains the outstanding papers presented at Southeast Asian Conference on Geophysics (SEACG) 2020. Due to Covid-19 Pandemic, the 3rd SEACG 2020 Conference was held online on 3 – 5 November 2020.
List of Committees SEACG 2020, Documetation, Images are available in this pdf.
Earthquake Swarm Analysis around Mt. Salak, West Java, Indonesia, Using BMKG Data from August 10 to November 24, 2019
Authors: Supendi Pepen , Puspito Nanang T. , Nugraha Andri Dian , Widiyantoro Sri , Abdullah Chalid Idham , Daryono  , Karnawati Dwikorita , Rohadi Supriyanto , Zulfakriza  , Sahara David P. 
Published: November 2021

AbstractEarthquake swarms commonly come approximately active tectonic and volcanic area. Interestingly, the swarm events occurred ~23 km southwest from Mt. Salak-Bogor, West Java, Indonesia, from August 10 to November 24, 2019, and were recorded by local/regional network of the Indonesian Agency for Meteorology, Climatology, and Geophysics (BMKG). Our previous study showed that in this area a destructive ML4.6 earthquake with thrust faulting occurred on September 8, 2012. The double-difference method was applied to update the hypocenter locations from the BMKG data. In the time period of ~3.5 months, we relocated 79 swarm events with ~9.4 km depth average for local magnitude (ML) 2.2 to 4.2. The source mechanism result for selected events shows a strike-slip faulting. Our interpretation is that these swarm events are probably related to stress change due to volcano-tectonic activity.
The Estimation of Seismic Site Amplification of Bukittinggi City, West Sumatera, Indonesia
Authors: Marjiyono  , Setiadi I , Setiawan J 
Published: November 2021

Abstract
Bukittinggi city area is exposed substantial risk of both, close to seismic source line and site amplification due to soft surface sediment / soil layer. The Great Sumateran Fault (GSF) which is crossing this area, notorious as a very active seismic source. Its responsible to some major earthquake in the vicinity of the fault line. Generally, Bukittinggi area is covered by volcanic product as pumiceous tuff. We applied combined array and single station microtremor measurement to characterize near surface sediment in this area. Based on analysis microtremor single station and array using spatial autocorrelation (SPAC) method, weathered surface layer thickness is in the range of 0-108 m with shear wave velocity in the range of 62-190 m/s, while the fresh pumiceous tuff is in the range of 375-629 m/s. The estimation of site amplification in this area which is indicated by mean amplification is in the range of 1-1.95. The high amplification zone is occupies the northernmost area and some area locally in the southern part of Bukittinggi city.
The Spatio-temporal Analysis of b-value in the Banda Arc, Indonesia
Authors: Al-Rasyid Muhammad Bani , Rusman Mira Nailufar , Hamonangan Daniel , Supendi Pepen , Kirana Kartika Hajar 
Published: November 2021

Abstract
Banda arc is a complex tectonic structure manifests by high seismicity due to the collision of a continent and an intra-oceanic island arc. Using the relocated earthquakes data from ISC-EHB and BMKG catalogues from the time period of 1960 to 2018, we have conducted a spatial and temporal variation of b-value using the Guttenberg-Richter formula in the area. Our results show that the spatial distribution of low b-values located in the south of Ambon Island and southeast of Buru Island. On the other hand, the temporal variation of b-value shows a decrease in the northern part of the Banda sea probably high potential to produce large earthquakes in the future. Therefore, further mitigation is needed to minimize the impact of earthquakes in the area.
Frequency Dependent Magnetic Susceptibility in Topsoil of Bandung City, Indonesia
Authors: Kirana K H , Apriliawardani J , Ariza D , Fitriani D , Agustine E , Bijaksana S , Fajar S J , Nugraha M G 
Published: November 2021

Abstract
Soil contains lithogenic components as well as anthropogenic components including combustion residues from traffic activities. The high traffic activities in major cities such as Bandung have caused the air pollution level to increase significantly. These activities might also produce significant combustion residues that accumulate, among others, in the topsoils. Compared with lithogenic components in topsoil, the anthropogenic combustion residues might have different magnetic signatures that could be detected by magnetic measurements. In this study, 38 topsoil samples from 19 roadside sampling points in Bandung City were collected and magnetically analysed to map the magnetic signatures due to traffic activities. The samples were measured for magnetic susceptibility using Bartington MS2B Susceptibility Meter and hysteresis parameter analysed from Vibrating Sample Magnetometer (VSM). The results show that the values of mass-specific magnetic susceptibility (χLF) vary from 391.20 to 1835.20×10-8 m3/kg with the average value of 1012.16 × 10-8 m3/kg while the values of frequency dependent susceptibility (χFD%) vary from 0.54% to 4.48% with the average value of 1.9%. The relatively high value of magnetic susceptibility indicates higher concentration of magnetic minerals compared to that of pristine topsoil around Bandung. This is in agreement with similar studies on roadside topsoil elsewhere. The poor correlation between mass-specific magnetic susceptibility and frequency dependent magnetic susceptibility infers that the magnetic minerals are predominantly non superparamagnetic. This finding is supported by magnetic hysteresis parameters showing that the predominant grains are likely to be pseudo-single domain (PSD) if magnetite is assumed to be the predominant magnetic mineral. Similar studies in German and China reported that the predominant magnetic mineral is mixture of single domain to multi domain magnetite.
Geomagnetic inverse modeling to estimate the volume of magnetization in areas with topographic variations
Authors: Wahyudi Eko J 
Published: November 2021

Abstract
A three-dimensional geomagnetic modeling is proposed to obtain information about a magnetization over topographic area from magnetic total force from land data survey. The model is divided into three-dimensional mesh grid of rectangular prisms that cover a finite depth below topographic elevation. The model parameter is assigned to each prism describing magnetization. A set of linear equations was formulated in terms of volume magnetization for each prism. The inverse calculation is obtained using the solution of over-determined problems. In this inverse calculation over three-dimensional mesh grid, the weighted matrix will be used to determine distribution of volume magnetization in the subsurface and keep the zero value of volume magnetization above the surface. A computer program has been tested with artificial topographic data and applied to digital elevation model of Bandung. The result of the inversion shows the comparison between synthetic model and inverse model to provide several analysis of algorithm performance. The high magnetization value can be characterize using inverse model up to 77% of volume area with average success recovery of model parameter value up to 56%.
Characteristic of the 2010-2020 Earthquakes in North Arm of Sulawesi based on Focal Mechanism and b-value
Authors: Astuti A P , Elsera E M , Massinai M F I , Akbar M A 
Published: November 2021

AbstractThe north arm of Sulawesi has a fairly high level of seismicity. The North Sulawesi arm is bounded in the south by the Palu-Koro Fault, the northern part is bounded by the North Sulawesi Trench and the Molluca Sea Thrust in the east. Therefore, this study aims to analyze the characteristic of the 2010-2020 earthquakes in the north arm of Sulawesi by analyzing the earthquake’s focal mechanism and mapping the b-value using the maximum likelihood method. From this study, we obtained the focal mechanism consist of thrust and strike-slip, this is due to the activity of faults and subduction zones in the North arm of Sulawesi such as the Palu-koro fault, the Gorontalo Fault, North Sulawesi Trench, Molucca Sea Collision, and several other faults that affect the seismicity of this region. The variation of the b-value ranging from 0.5-1.1 These studies indicate that thrust fault regions have lower b-values, while strike-slip fault regions have intermediate b-values. Meanwhile, areas with active volcanoes tend to have high b-values. The results of this research can be used as a basis for decision making related to earthquake mitigation in this area in the future.
Focal Mechanism Analysis of the September 25th, 2019 Mw 6.5 Ambon Earthquake and Its Implication for Seismotectonics
Authors: Daniarsyad Gatut , Vita Aprilia Nur , Wei Shengji 
Published: November 2021

Abstract
On September 25th, 2019, an Mw 6.5 earthquake occurred in Ambon, Maluku Province, Indonesia, and caused casualties and infrastructures damages. The epicenter located in a tectonically active region with the potential strike-slip and thrust faulting earthquake sources, yet the responsible fault is still not well understood. Based on focal mechanism solutions from available seismological agencies, i.e. USGS, GFZ, GCMT, and BMKG, the earthquake has a similar strike-slip focal mechanism, although there are discrepancies on detailed source parameters. To provide a better understanding of the earthquake mechanism and seismotectonic, we apply the Cut-and-Paste (CAP) focal mechanism inversion method to broadband seismic waveforms from regional and teleseismic distances. The CAP inversion results on the regional data grouped in different distance ranges show a robust strike-slip solution. We then refine the earthquake focal depth by performing the CAPtele inversion and resulted in a depth of 12 km with similar fault plane solution as the regionals. The ruptured fault plane is resolved by a directivity analysis using azimuthal pattern of the apparent source durations, which indicates an obvious unilateral rupture propagation toward SSE direction. Our result suggests the NNW-SSE orientated fault is the ruptured fault plane, which is also consistent with the near N-S distributed aftershocks. This fault is located in a narrow sea between Seram, Ambon and Haruku island and was not reported yet in previous studies. The Coulomb failure stress (CFS) changes analysis of the mainshock shows that the Ambon earthquake has promoted the off-fault aftershocks which occurred to the west of the ruptured fault.
Results of land subsidence measurement using GPS method in the Jakarta groundwater basin in 2015-2019
Authors: Abdullah F M , Andriyanto H , Nababan J R , Abdillah F , Sulistyawan R I H 
Published: November 2021

Abstract
The development of population and development activities in big cities in Indonesia, especially in the city of Jakarta and surrounding areas is very rapid. From several land subsidence studies, several factors have been identified that cause land subsidence, namely: excessive groundwater extraction, reduction due to building/infrastructure loads, subsidence due to natural consolidation of soft soil layers, and subsidence due to tectonic forces. At present the exploitation of ground water for industrial and residential needs is at a level that needs attention. Excessive pumping of groundwater will cause a decrease in the quantity of ground water, entry of seawater into the land (sea water intrusion) and land subsidence. Symptoms of the negative impact of land subsidence have been felt in several areas, especially in industrial areas located in the northern part of Jakarta. This land subsidence can be measured by GPS or satellite geodetic method, which have begun to develop in Indonesia in the past two decades. Measurements were made using the radial method at 53 GPS points in 2015 up to 100 measurement points in 2019 in Jakarta Groundwater Basin. The result of these campaign GPS surveys that is northern part of Jakarta relatively had higher subsidence rate than the southern. The largest subsidence almost reached 6.2 cm/year in Muara Baru in northern area which is southern area only suffered an average rate of 1.16 cm/year.
The determination of prospective reservoirs in the slope environment of the Tarakan Basin (Indonesia) by using sequence stratigraphy, rock physics and AI inversion
Authors: Aminulloh D , Tampubolon B T , Sukmono S 
Published: November 2021

Abstract
Prospective reservoirs in the Tarakan Basin are mostly deposited in the Middle Miocene to Pliocene and related to the change of depositional environment from transgressive to regressive sedimentary environment. Log sequence stratigraphic analysis in well AST 1 shows that transgressive and lowstand system tracts were deposited during the study area. Hashin-Shtrikman method is used in the rock physics analysis to identify the relative rock hardness and integrated with gamma ray log, NPHI, and resistivity data analysis. The result show that potential reservoir exist at the depth range of 7650-7725 feets and associates with low velocity, low gamma ray, low NPHI, high resistivity values. The potential reservoir interval was deposited under low stand system tract of slope depositional environment. The acoustic impedance (AI) map shows that the low AI’s are mostly located in the northwestern part of the study area.
Exploring Reservoir within Hugin Formation in Theta Vest Structure using 4-D Seismic and Machine Learning Approach
Authors: Hardanto Lilik T. , Abdurrachman Mirzam , Nugroho Dwiharso 
Published: November 2021

Abstract
This paper aims to identify the oil distribution using 4-D seismic below a complex 3-D surface in Hugin Formation using machine learning and geobody detection. The exploration well 15/9-19-SR, drilled to the Theta Vest structure, was based on the interpretation of reprocessed ST8215R 3-D seismic survey data from 1991 in the Sleipner area, encountered oil in the Jurassic Hugin Formation. The drills stem test showed outstanding production capacities through time, with low water cut and low GOR. 4-D seismic has all the traditional benefits of 3-D seismic. A significant additional potential benefit is that fluid-flow processes can be directly imaged. The 4-D seismic analysis was conducted in 2012 to repeat the 3-D seismic surveys and analyze images in time-lapse mode to monitor time-varying fluid-flow processes during reservoir production. A comprehensive study of the structure and the discovery has been performed and is reported. The DNN method to predict facies far away from existing production wells by using facies log well to supervise seismic inversion created by the Seismic Color Inversion method. It can detect some oil pockets distribution and risk the well planning and the right candidate for new proposed wells.
Extensive Investigation of the Land Subsidence Impressions on Gedebage District, Bandung, Indonesia
Authors: Gumilar I , Sidiq TP. , Meilano I , Bramanto B , Pambudi G 
Published: November 2021

Abstract
Gedebage district is presently experiencing rapid and mass infrastructure development and becoming one of the developed districts in Bandung, Indonesia. A football stadium, several luxury housing, the grand mosque of West Java province, and a business center have been built in this district. However, it is well known that the Gedebage district has turned into one of the Bandung districts that suffers from land subsidence phenomena. Since 2000, the Gedebage district has suffered land subsidence at an average rate of 10 cm per year and becoming one of the fastest sinking districts in Bandung. This fast land subsidence phenomenon is suspected of affecting the infrastructure in this district. Therefore, this work aims to capture the current subsidence rate in the Gedebage district using the geodetic approach of the combination of the Global Navigation Satellite System (GNSS) with Interferometric Synthetic Aperture Radar (InSAR) and investigate the impact of land subsidence on infrastructures in Gedebage district. We use GNSS campaign datasets from the years 2016 and 2019. Each GNSS campaign was performed at least 10-12 hours of observations. We also utilize a similar period of 2016 to 2019 for the InSAR datasets. Utilizing both GNSS and InSAR datasets, we can capture the subsidence with the rate reaching 4 -15 cm per year between 2016 and 2019, and it occurs uniformly in this district. The impact of land subsidence occurred in almost all urban areas in the Gedebage district. These impacts include cracks in buildings, bridges and roads, and also tilted buildings.
Verification of the Jakarta Geoid Model from the Gravity Data of 2.5 km Resolution with Gravimetric Geoid
Authors: Ramdani D , Safi’i A N , Hartanto P , Oktaviani N , Hariyono M I 
Published: November 2021

Abstract
To use the Global Navigation Satellite System (GNSS) correctly, the height information should be transformed into orthometric height by subtracting geoid undulation from it. This orthometric height is commonly used for practical purposes. In 2015 geoid of Jakarta has been produced, and it has an accuracy of 0.076 m. In the year 2019, airborne gravimetry has been done for the entire Java Island. The area of DKI Province cannot be measured because there is inhibition from Airnav. For this reason, terrestrial gravimetric measurements are carried out in this region by adding points outside the previously measured area. To compute the geoid in the Jakarta region is needed the Global Geopotential Model (GGM). In this paper, the GMM used is gif48. The “remove and restore” method will be used in calculating the geoid in this Jakarta region. Besides that in this geoid calculation also uses Stokes kernel and FFT to speed up the calculation. The verification of the resulting geoid is carried with 11 points in DKI Jakarta Province. This verification produces a standard deviation of 0.116 m and a root mean square of 0.411 m.
Early Results of Time Domain Receiver Function Data Processing in Mt Merapi and Mt Merbabu
Authors: Ilahi A K , Auly M F R , Zaky D A , Abdullah A , Nugroho R P , Suhardja S K , Nugraha A D , Zulfakriza Z , Widiyantoro S , Métaxian J P , Ramdhan M 
Published: November 2021

Abstract
The receiver function method is a method to image the earth subsurface by utilizing Ps conversion waves that are formed due to the velocity boundary. In general, the receiver function method estimates depth of structures such as the mantle-crust boundary by deconvoluting the vertical component from the horizontal component. Typical receiver function data processing is done in the frequency domain where the deconvolution process can be seen as a division between two components. In this study, we tried to reprocess the data using a deconvolution technique in time domain, popularly known as iterative time-domain deconvolution. The principle of iterative time domain deconvolution consists of iterative cross-correlation between the horizontal and vertical component. We use data from the DOMERAPI seismic station network located in the vicinity of Mt Merapi and Mt Merbabu. Mt Merapi is one of the most active volcanoes in the world with frequent eruptions and located at the ring of fire chain volcano in Indonesia. Note that the previous receiver function study in this region showed complex signals at some stations that may be related to sediment at shallow sediment and possible layers of low velocity zone that interfering main signal for a crust-mantle boundary. Our current results show iterative time domain RFs have clearer and smoother signal than the frequency domain that help interpreting the waveform signals. We estimate a range of crust thickness between 26-31 km near Mt Merapi. However, we noticed that iterative time domain calculation requires longer computation time and input signal.
Analysis of M 5.3 Sumbawa, Indonesia earthquake 2020 and its aftershocks based on hypocenter relocation from BMKG seismic stations
Authors: Ramdhan M , Priyobudi  , Mursityanto A , Palgunadi K H , Daryono  
Published: November 2021

AbstractThe 2020 Sumbawa earthquake of moderate magnitude (M 5.3) produced very significant aftershocks. Based on the computation of Utsu’s method, those aftershocks would be ended after the 20th day. Those earthquakes along 20 days were relocated using double-difference method. The relocation results show the southwest-northeast orientation and getting deeper into the northwest direction. Those two directions show the strike and the dip from the fault plane of the earthquake which was consistent with the focal mechanism released by the Indonesian Agency for Meteorology, Climatology, and Geophysics (BMKG). Those results showed the majority of earthquakes occurred at a depth of shallower than 20 km. Those earthquake depths were fit with the previous study showing the crustal thickness beneath Sumbawa Island that was about 28 km. We also found that those earthquakes occurred at splay faults propagating to decollement structure. This study is beneficial for earthquake disaster mitigation especially in updating active faults on Sumbawa Island.
Determination of Earthquake Hypocenter Distribution using the Modified Joint Hypocenter Determination (MJHD) Method throughout the Palu-Koro Fault (Case Study: August-October, 2018)
Authors: Swastika Dewi Ayu , Lestari Harmita , Astuti Aulia Puji , Aswad Sabrianto , Ismullah Massinai Muhammad Fawzy 
Published: November 2021

Abstract
The area of Sulawesi, especially along the Palu Koro Fault, is an area that is largely influenced by the confluence and movement of plates as well as regional fault activity pathways with high levels of seismicity. Determining the location of the hypocenter accurately through relocation is required in identifying the detailed tectonic structures in the area. Relocation of the hypocenter using the Modified Joint Hypocenter Determination (MJHD) method using the IASP91 velocity model in the period August to October 2018 with the arrival time data from BMKG catalog. The results of hypocenter relocation using the MJHD method show that from 132 earthquake distribution points to 63 earthquake hypocenter points after the relocation. The change in the location of the hypocenter was much denser along the Palu Koro Fault route than before the relocation as evidenced by the mean value of rms (root mean square) before relocation was 1.31 and after relocation it became smaller (0.61). Changes in parameter values after relocation using the MJHD method caused the distribution of the earthquake hypocenter to be tighter towards the Palu Koro fault than before the relocation, where the distribution had a random and scattered pattern.