Baribis Fault Research Articles

Subsurface Characterization and Revealing Geometry of the Baribis Fault in the Eastern Part of West Java Fault Using Long-Offset Resistivity Tomography

Subsurface Characterization and Revealing Geometry of the Baribis Fault in the Eastern Part of West Java Fault Using Long-Offset Resistivity Tomography

Local cultural coping strategies to mitigate the impact of Baribis Fault disasters

Baribis Fault disasters caused the loss of human lives. This study investigates the strategies local communities employ in Indonesia to cope with disasters. A qualitative study was conducted on various cultural strategies used to mitigate disasters in relevant areas. These strategies were selected based on the criteria of locally based traditional oral and written knowledge obtained through intensive interviews. The study reveals that technological and earth science solutions are insufficient to resolve disasters resulting from Baribis Fault activity. Still, local culture and knowledge also play a crucial role in disaster mitigation. The study contributes to a deeper understanding of how cultural strategies avoid disasters and highlights the need to transform local knowledge regarding effective cultural strategies for mitigating such disasters. This transformation can have positive psychological implications and enhance community harmony.

The origin of Baribis Fault and its relationship to the dynamics of Sunda Arc

The origin of Baribis Fault and its relationship to the dynamics of Sunda Arc

Assistance in the Preparation of the Cikole Village Disaster Risk Reduction Handbook

West Java Province is one of the provinces in Indonesia that is prone to earthquakes. There are three faults that stretch across West Java, namely the Cimandiri Fault, the Lembang Fault, and the Baribis Fault. The Lembang Fault is a geological phenomenon located in the north of the Bandung Basin, stretching from the eastern part of Mount Manglayang to the western part of Parongpong-Csarua through the city of Lembang, for 22 km. The morphology along the Lembang Fault includes active tectonics which can cause large earthquakes in the surrounding area. Among them is Cikole Village, Lembang District. Initial search results show that the people of Cikole Village still have low-disaster risk reduction efforts. Increasing preparedness is one of the important elements of proactive disaster risk reduction activities before a disaster occurs. The priority problem that needs to be addressed through mentoring activities is to increase community preparedness through the preparation of guidelines in the form of a disaster risk reduction handbook. The method used in this activity is community involvement through focus group discussion (FGD). The developed pocketbook measures 7.4 x 10.5 cm and is designed with the dominant color orange. Because orange color denotes alert or ready. The contents of the book include disaster threats in Cikole Village and a guide to disaster preparedness for earthquakes and volcanic eruptions.
 Keywords: disaster risk reduction, handbook, Sesar Lembang

PELATIHAN KESELAMATAN TERHADAP GEMPA DI KELURAHAN BENDUNG KECAMATAN KASEMEN KOTA SERANG

Indonesia is an earthquake-prone country. Almost all of the islands in Indonesia lie in the ring of fire of the world's earthquakes. Earthquake disasters often occur and cause a lot of loss, both property and casualties. However, until now, education for the public to be prepared for earthquake disasters is still inadequate. The community is always unprepared and only resigned to fate in facing the earthquake. Earthquake disaster mitigation is generally the responsibility of the government, but the government itself cannot make effective efforts without the help of experts and the participation of the community itself. The PKM Earthquake Safety Training Program is aimed at the people of Kelurahan Bendung, Kecamatan Kasemen, Serang, Banten because based on the findings of the latest earthquake fault, namely the Baribis Fault, the area has the potential for a large earthquake to occur. This program aims to educate the people there about prevention efforts before an earthquake occurs, what to do when an earthquake occurs, and what to do after an earthquake occurs. It is hoped that the knowledge provided will be useful, and the people there can be prepared for earthquake disasters, so that loss of life and property due to the earthquake can be diminished.

3-D shallow shear velocity structure of the Jakarta Basin from transdimensional ambient noise tomography.

Situated on the northern coast of the Indonesian island of Java, Jakarta and its metropolitan area (Greater Jakarta) are subject to significant earthquake hazards from a subduction zone south of Java and nearby active crustal faults. The seismic risk may be even higher because Greater Jakarta resides on a sedimentary basin filled with thick Pliocene-Pleistocene sediments. A comprehensive study of Jakarta Basin's properties and geometry is important for creating robust seismic hazard and risk assessments. The main objective of this study is to develop a 3-D model of Jakarta Basin's shallow shear-wave velocity (VS ) structure and improve on previous models that did not cover the basin edge due to the extent of data coverage. Between April and October 2018, we deployed a new temporary seismic network to extend the spatial coverage beyond that of a previous deployment in 2013, and sampled 143 locations through sequential deployments of 30 broad-band sensors covering Jakarta and its adjacent areas. We conducted a 2-stage transdimensional Bayesian inversion of Rayleigh wave phase velocity dispersion curves derived from seismic noise. To begin, we applied tomography and constructed 2-D phase velocity maps for periods 1-5s. Then, at each point in a regular grid defined on these maps, we invert each dispersion curve into 1-D depth profiles of VS . Finally, these profiles at gridpoints with ∼2km spacing are interpolated to form a pseudo-3-D VS model. Our results reveal the edge of the Pliocene-Pleistocene sediments along the south. Also, we resolve a basement offset across south Jakarta that we suggest may be related to the western extension of the Baribis Fault (alternatively, the West Java Backarc Thrust). We recommend using this 3-D model of the Jakarta Basin for scenario earthquake ground motion simulations. Such simulations would help establish how important it might be to re-assess seismic hazard and risk in Greater Jakarta so that basin resonance and amplification are considered.

Geodetic Strain of the Baribis Fault Zone in West Java, Indonesia

The Baribis Fault’s status, which is located in the northern part of Java, as an active or inactive fault is a matter of considerable debate. In this study, we investigate the strain rate of the Baribis fault zone’s segment in northeastern West Java, Indonesia, as revealed by a dense network of GPS stations. We analyzed 17 surveyed GPS stations combined with continuous GPS sites over West Java from 2017 to 2021, then we estimate the GPS velocities fields. We calculated the strain rate and estimated it from the GPS velocities. In general, the Baribis fault zone experiences a significant strain rate (> 50 nano-strain/yr) with the compressional dilatation strain associated with the ongoing deformation in that area. The dilatation strain suggest that the northeastern Baribis fault in the West Java is an active thrust fault system. This information is essential to supporting a disaster mitigation program.

Implications for fault locking south of Jakarta from an investigation of seismic activity along the Baribis fault, northwestern Java, Indonesia

Recent borehole seismic deployments conducted along the Baribis Fault in northwestern Java reveal that it may be active. In this study, we exploit these data to locate proximal earthquakes using a relative relocation technique, estimate their moment magnitudes using a spectral fitting method and compute their focal mechanisms via waveform inversion. We observe that seismicity in the eastern part of the fault is significantly higher than in the west, where a previous GPS study of the region south of Jakarta demonstrated the existence of high compression rates. These observations imply that the western Baribis Fault is locked, and that neighbouring areas, including southern Jakarta and its surroundings, may be highly vulnerable to future sizeable earthquakes when accumulated elastic strain energy is eventually released during fault rupture. Significantly, the current generation of Indonesia’s national hazard maps have not considered seismicity along the Baribis Fault. Our new results therefore call for an urgent reappraisal of the seismic hazard in northwestern Java that carefully takes into account the Baribis Fault and its earthquake potential, particularly in light of its proximity to Jakarta, a megacity that lies at the heart of one of the most densely populated islands in the world.

Fault rupture in Baribis Fault possibly related to the 1847 major earthquake event in the Cirebon area

Baribis Fault is a recently identified active fault known to have thrust movement which located along the northern part of the West Java area. This E-W striking fault runs across high-populated areas, including Cirebon, Indramayu, Sumedang, and Subang area (with a probability of continuing to Jakarta and Banten areas). The last major historical earthquake occurred on November 16th, 1847 around the fault line with a radius of shaking area up to 400 km. The available high-resolution Digital Elevation Model from Geospatial Information Agency, called DEMNAS, has about 7.5-m grid data resolution but still not adequate to be used for identifying fault ruptures of this event. Hence, we conducted an Unmanned Aerial Vehicle (UAV) 3D Photogrammetry survey flown in the lower latitude (~100-m high) in the suspected sites. This study identified clear fault scarp associated with stream-valley offsets indicating strike-slip movement in the Ujung Jaya subdistrict, Sumedang. The trace of fault rupture has a 5±1-meter sinistral offset. This sharp fault deformation feature is possibly related to the 1847 earthquake in this area. This fact is different from regional morphology, which shows that the Baribis Fault is a thrust. Further study is necessary to get more detailed and precise information.

Tracing Baribis active fault continuity in the Subang region using gravity edge detection analysis

Elucidating the Baribis active fault in the central part of West Java is challenging due to the lack of physiography appearance. A gravity survey was conducted on 838 stations around the North of Bandung to Subang region to identify its buried spatial fault continuity. Regular processing routine reduced the observed gravity acceleration to generate the refined Bouguer anomaly map. Additionally, edge detection techniques (e.g., tilt derivative and analytic signal) were analyzed to delineate the proven fault emergence from the published active fault database and surface geological map. The results depict that the Baribis fault was continued to the Subang region and enhanced clearly by applying analytic signal attributes. Thereby, the Baribis fault continuity is better interpreted on the analytic signal anomaly map, whereas the tilt derivative technique explains the factor of unclear surficial discontinuity of Baribis fault on the zone.

Long and Short Wavelength of Geodetic Strain Rate Tapering Earthquake Potential in Western Java

Shallow earthquake produced by intra-island fault in a populated region could be a catastrophic disaster. Java island is the most populated area specifically in Western Java since there include Jakarta, the capital city of Indonesia. Cimandiri, Lembang and Baribis fault as main intra-island fault are considered to be responsible due to some shallow historical earthquake in Western Java. However, convergent plate margin such as Java Island generates a broad spectrum of deformation pattern that potentially distracts the deformation due to Baribis fault. In addition, slow relative motion of Sunda block and postseismic deformation due to the 2006 Java tsunami earthquake involve along those fault. Here, we intend to conduct a wavelength decomposition of strain rate calculated from GNSS (Global Navigation Satellite System) data. We expect to separate long wavelength due to wider-region deformation such as deformation due to the interacting plate and postseismic deformation to obtain Short wavelength due to each fault. We utilized the daily position of recent continuous geodetic data to produce strain rate. Therefore, we could apply a moving average filter to extract a short wavelength component. We obtained long wavelength (-150 to 150 nanostrain/yr) in Western Java shows extension indicating the postseismic effect is still continuous while short wavelength (-75 to 75 nanostrain/yr) varies in space.

TECTONIC AND GEOLOGICAL STRUCTURES OF GUNUNG KROMONG, WEST JAVA, INDONESIA

The Gunung Kromong complex is a solitary hill which physiographically located within the Jakarta Coastal Plain Zone. The research is mainly formed of primary data from observations and measurements of all geological elements especially morphological aspects and geological structures to reveal the tectonic background and its relation to the oil seepage. Sedimentary rocks outcrops appear in the western part around the cement plant surrounded by well exposed of igneous rocks. Oil seepage, gas and hot springs are found in limestone which has high fracture intensity and at low elevation. The distribution of sedimentary rocks is not only controlled by the folds and fault structures but also influenced by the igneous rock intrusion. The alignment of the structure in West Palimanan is formed by steep slopes on dacite igneous rock which is concluded as fault scarp. There are found abundance of fault indications in the form of slickenside, fault breccias, millonites, drag folds and have high intensity of shear joint. The KRG-7, KRG-8 and KRG-9 observation points, a slickenside with the same plane was found but has different slicken line, each shows a thrust fault and normal faults. The direction of slickenside divided into 4 units of fault groups. The series of hills in the south of the Baribis Fault occur because of the lifting through the fold and the thrust faults mechanism. The thrust fault in the Gunung Kromong complex is the hanging wall section of the Baribis thrust fault, so that it belongs to the leading thrust system.

VARIASI STRAIN DI SEKITAR SESAR BARIBIS BERDASARKAN DATA PENGAMATAN GPS KONTINYU (2016-2018)

Java island is one of big island with a high geodynamic condition, which in the southern part of Java Island occur subduction between Sunda Block and Indo-Australian Plate. The subduction zone forms a regional geological pattern in the maindland of Java which can be seen as fault pattern. Baribis fault is one of the active fault in the west Java, which consist west and east segment. The west segment called by inferred fault, while the east segment called by fix fault. This paper discusses about the strain variation along Baribis fault based on GNSS data, that used to see the geodynamic behavior between Indo-Australian plate and the Sunda block.The velocity and the coordinates of observation point is calculated using weight least square method in the GAMIT and GLOBK 10.7 software, while the principle strain rate calculated using least square collocation method in GeoStrain software. The result show compression happen in the northern part of Banten province, western part of DKI Jakarta and western part of West Java province. Meanwhile the extension happened in eastern part of DKI Jakarta till the southern part of DKI Jakarta.

Peak Ground Acceleration and Earthquake Intensity Microzonation in Watukumpul, Pemalang Regency

Watukumpul is located in Pemalang District, Central Java, which is adjacent to the fault seismotectonic line of Baribis fault in the north and subduction area of the Eurasian and Indies-Australian plates in the south. It makes Watukumpul often experiences an earthquake. This study aimed to map the peak ground acceleration calculated using the Kanai equation and earthquake intensity calculated using Wald equations in Watukumpul. This study used historical earthquake data occurred in 1988-April 2018 from the International Seismological Center and microtremor measurements of 33 points. Microtremor data were processed using the Horizontal to Vertical Spectral Ratio method and resulted the predominant period of study area ranged from 0.13 to 0.74 s. The results showed that the study area had a PGA value of 26.93 - 63.25 gal. The intensity calculation showed that the study area has the potential for earthquake damage with an III-IV MMI scale.
 
 Keywords: Kanai, Watukumpul, Intensity, Earthquake

Analisis Seismisitas Berdasarkan Data Gempa Bumi Periode 1958-2018 Menggunakan b-Value Pada Daerah Selatan Jawa Barat dan Banten

The area of West Java and Banten, especially is Southern is one of the areas prone to earthquakes, caused by the fact that the area is part of the ring of fire path and the presence of faults that are still active faults, such as the Cimandiri Fault, the Baribis Fault and the Lembang Fault. The purpose of this study is to determine the level of seismic activity, the fragility of the rocks and the level of the return period to make earthquake resistant buildings. The seismotechnical parameters of a region can be calculated using the Frequency-Magnitude relationship with the Guttenberg-Rithcher formulation, namely by using the Maximum Likelihood method. Based on the results of the research obtained from the combined data of USGS and BMKG, the magnitude of the 4 SR and the depths of 0-300 km. Based on the analysis and distribution of seismicity, it was found that the higher of the frequency the smaller earthquake magnitude is obtained. The results of the seismotechnical parameters provide variations of the b-value in South West Java and Banten around 0.95-1.45, with the highest value in the South of Pandeglang Regency (1.35-1.45) and the lowest in Tasikmalaya District (0.95-1.05). Variations of the a-values of an area around 6.5-9, while the highest value is in the South of Pandeglang Regency (8.5-9) and the lowest in Tasikmalaya Regency (6.5-7). The Seismicity Index is 0.632 and the Seismicity of the largest earthquakes is 0.004. Probability is at a time interval of 20 years with value as follows P (7.20) = 8%; P (7.40) = 15%; P (7.60); 21%. While variation of the return period are with variations of 5 SR = 1-4 years, 6 SR = 15-55 years and 7 SR = 150-550 years

Geology Structure Identification Using Pre-Stack Depth Migration (PSDM) Method of Tomography Result in North West Java Basin

North West Java Basin is a tertiary sedimentary basin which is located in the right of the western part of the Java island. North West Java Basin is geodynamic where currently located at the rear position of the path of the volcanic arc of Java that is the result of the India-Australia plate subduction to the south towards the Eurasian plate (Explanation of Sunda) in the north. Geology structure observation is difficult to be conducted at Quaternary volcanicfield due to the classical problem at tropical region. In the study interpretation of fault structures can be done on a cross-section of Pre-Stack Depth Migration (PSDM) used prayer namely Hardware Key Device, ie Central Processing Unit: RedHat Enterprise Linux AS 5.0, prayer Monitor 24-inch pieces, Server: SGI altix 450/SuSe Linux Enterprise Server 9.0, 32 GB, 32 X 2,6 GHz Procesor, network: Gigabyte 1 Gb/s, and the software used is paradigm, product: Seismic Processing and Imaging. The third fault obtained in this study in accordance with the geological information derived from previous research conducted by geologists. The second general direction is northwest-southeast direction represented by Baribis fault, fault-fault in the Valley Cimandiri and Gunung Walat. This direction is often known as the directions Meratus (Meratus Trend). Meratus directions interpreted as directions that follow the pattern of continuous arc Cretaceous age to Meratus in Kalimantan.

Slip Rate Estimation of the Lembang Fault West Java from Geodetic Observation

The Sunda arc forms the southern border of the Indonesia Archipelago, where the Indo-Australian plate is subducted beneath Eurasia. The age of subducting plate increases from Sumatra in the west to Flores in the east. The increase in age is consistent with an increase in plate dip along the arc and an increasing depth of seismic activity. The motion of Australia with respect to West Java is 68 mm/yr in a direction N11E orthogonal to the trench. A number of active faults characterizing this area include Cimandiri fault, Lembang fault and Baribis fault. This research uses campaign and continues GPS data to make a preliminary estimation of the slip rate of Lembang fault. Our GPS measurements suggest that Lembang fault has shallow creeping and deeper locking portion. The estimated slip rate is 6 mm/yr with fault locking at 3-15 km and shallow creeping with the same rate. While the results are preliminary and we need more data for reliable estimations, we point out that these data can contribute to earthquake risk assessment by constraining earthquake recurrence relationships.

CRUSTAL DEFORMATION STUDIES IN JAVA (INDONESIA) USING GPS

Along the Java trench the Australian–Oceanic plate is moving and pushing onto and subducting beneath the Java continental crust at a relative motion of about 70 mm/yr in NNE direction. This subduction-zone process imposed tectonic stresses on the fore-arc region offshore and on the land of Java, thus causing the formation of earthquake fault zones to accommodate the plate movement. Historically, several large earthquakes happened in Java, including West Java. This research use GPS surveys method to study the inter-seismic deformation of three active faults in West Java region (i.e. Cimandiri, Lembang and Baribis faults), and the co-seismic and post-seismic deformation related to the May 2006 Yogyakarta and the July 2006 South Java earthquakes.Based on GPS surveys results it was found that the area around Cimandiri, Lembang and Baribis fault zones have the horizontal displacements of about 1 to 2 cm/yr or less. Further research is however still needed to extract the real inter-seismic deformation of the faults from those GPS-derived displacements. GPS surveys have also estimated that the May 2006 Yogyakarta earthquake was caused by the sinistral movement of the (Opak) fault with horizontal co-seismic deformation that generally was less than 10 cm. The post-seismic horizontal deformation of the July 2006 South Java tsunami earthquake has also been estimated using GPS surveys data. In the first year after the earthquake (2006 to 2007), the post-seismic deformation is generally less than 5 cm; and it becomes generally less than 3 cm in the second year (2007 to 2008).

KARAKTERISTIK DISTRIBUSI MINERAL UBAHAN: JEJAK EPISODE KEGIATAN HIDROTERMAL DI DAERAH CUPUNAGARA, SUBANG, JAWA BARAT

Cupunagara Area, lies in the North-Northeastern of the Sunda Volcanic Complex, occupied by rough mountainous area consisting of two calderas and surrounded by several volcanic cones. The lithology of the studied area consists of intrusive rocks unit, andesitic – basaltic lava and pyroclastic, mostly had been altered into prophylitic and argillic zones. The prophylitic zone is distributed widely in the central part of the calderas, whilst the argillic zone is distributed confined to the Northwest-Southeast trending fault zones overprints the prophylitic zone and contains the remnants of quartz veins. Structural geology pattern of the studied area is affected by its position as the meeting area of the Cimandiri and the Baribis Fault Systems. Two main strike slip faults are recognized consist of the Northeast-Southwest trending sinistral fault and the Northwest-Southeast trending dextral fault. Two episodes of hydrothermal activities occurred in the studied area, in the first episode the hydrothermal fluid was relatively hot (temperature between >100 to 250 o C) and neutral (pH 5-6), whilst in the second its temperature was <100 o C and acid. The first episode was triggered by the Oligo-Miocene tectonic activity (the formation of the Northeast-Southwest fault zone), the controlling factor of the hydrothermal alteration distribution were the permeability of the host rocks and fault zones, altered the mineralogy of the host rocks into the prophylitic alteration assemblage and formed quartz veins. The second episode was triggered by the Plio-Pleistocene tectonic activity (the formation of the Northwest-Southeast fault zone), altered (overprinted) the wall rocks into the argillic alteration assemblage, the controlling factor was the fault zones.