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JLBG (Jurnal Lingkungan dan Bencana Geologi) (Journal of Environment and Geological Hazards)
ISSN : 20867794     EISSN : 25028804     DOI : -
Core Subject : Science, Social,
Jurnal Lingkungan dan Bencana Geologi (JLBG) merupakan terbitan berkala Pusat Air Tanah dan Geologi Tata Lingkungan, yang terbit triwulan (tiga nomor) dalam setahun sejak tahun 2010. Bulan terbit setiap tahunnya adalah bulan April, Agustus dan Desember. JLBG telah terakreditasi LIPI dengan nomor akreditasi 692/AU/P2MI-LIPI/07/2015.
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Articles 218 Documents
Potensi Penguatan Gelombang Gempabumi oleh Sedimen Permukaan Kota Mataram, Nusa Tenggara Barat Marjiyono Marjiyono
Jurnal Lingkungan dan Bencana Geologi Vol 7, No 3 (2016)
Publisher : Badan Geologi

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (3060.058 KB) | DOI: 10.34126/jlbg.v7i3.104

Abstract

ABSTRAKKerusakan bangunan dan infrastruktur oleh goncangan gempa bumi di suatu wilayah tidak hanya disebabkan oleh magnitudo atau kekuatan dan jarak ke pusat gempa bumi, tetapi juga sangat dipengaruhi oleh kondisi geologi permukaannya. Karakterisasi litologi permukaan perlu dilakukan dalam rangka untuk memperkirakan tingkat penguatan gelombang gempa bumi. Kombinasi pengukuran mikrotremor single station dan array telah dilakukan di Kota Mataram untuk memodelkan kondisi geologi bawah permukaan. Perhitungan nilai faktor penguatan gelombang dilakukan dengan menggunakan pendekatan fungsi alih gelombang geser horizontal 1D. Hasil perhitungan menunjukkan nilai faktor penguatan gelombang Kota Mataram berkisar antara 1,1 - 2,2. Potensi penguatan gelombang tinggi berada di bagian barat Kota Mataram.Kata kunci: fungsi alih gelombang geser horizontal, kecepatan gelombang geser,mikrotremor, penguatan gelombangABSTRACTDamage of infrastructure and building due to ground shaking within a region is not merely caused by the magnitude and distance from earthquake source, but it is also affected by surface geological condition. In order to find out site amplification level of Mataram City, the single station and array microtremor survey have been conducted to identify its soil properties. The site amplification is calculated using 1DSH transfer function approximation andthe result rangesin 1.1-2.2. The western part of Mataram shows higher amplification area.Keyword : SH transfer function, shear wave velocity,microtremor, site amplification
Ekstraksi Aspek Geomorfologi (Scarps)Pada Citra Fusi Landsat 7 dan Terrasar-X untuk Meningkatkan Tingkat Kedetailan Zonasi Kerentanan Gerakan Tanah (Kasus Kabupaten Cianjur) Fitriani Agustin; Sukristiyanti Sukristiyanti; Yukni Arifianti
Jurnal Lingkungan dan Bencana Geologi Vol 6, No 1 (2015)
Publisher : Badan Geologi

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1377.816 KB) | DOI: 10.34126/jlbg.v6i1.71

Abstract

ABSTRAKMorfologi scarp (gawir) yang berbentuk concave/cekung dapat dijadikan indikasi adanya potensi gerakan tanah dan dapat di identifikasi melalui interpretasi citra satelit. Wilayah Kabupaten Cianjur dan sekitarnya adalah salah satu daerah yang rentan terhadap bencana gerakan tanah. Hampir 80% desa di Cianjur berpotensi terhadap bencana tersebut, dengan zona kerentanan gerakan tanah tinggi sebesar 17,24% dari total wilayah Kabupaten Cianjur (Sumber: Peta Zona Kerentanan Gerakan Tanah – PVMBG). Tujuan penelitian ini adalah mengidentifikasi bentukan scarp dan mendelineasi area potensi gerakan tanah di wilayah Cianjur dan sekitarnya. Metode yang digunakan adalah interpretasi visual pada citra hasil fusi antara Landsat 7 dan DSM TerraSAR-X, dan memvalidasi lokasi bentukan scarp dengan titik lokasi gerakan tanah (bersumber dari BPBD Kabupaten Cianjur) dan Peta Zona Kerentanan Gerakan Tanah - PVMBG. Hasil penelitian menunjukkan bahwa sebagian besar bentukan scarp merupakan indikasi area gerakan tanah. Selain morfologi scarp (gawir), bentukan geomorfologi lain seperti kipas vulkanik juga berpotensi gerakan tanah yang harus diwaspadai. Daerah berpotensi gerakan tanah di sekitar scarp bisa dipergunakan untuk melakukan revisi Peta Zona Kerentanan Gerakan Tanah dan juga dimanfaatkan untuk penataan ruang. Data citra penginderaan jauh terutama DSM dari citraTerraSAR-X dengan resolusi menengah sekitar 9m, dapat dijadikan data dasar untuk mengidentifikasi bentukan scarp dan zona gerakan tanah yang disebabkan oleh bentukan morfologi tersebut.Kata kunci: scarp, gerakan tanah, Cianjur, Landsat 7, TerraSAR-XABSTRACTScarp morphology in concave form can be an indication of the availability of earth movement potential and it can be identified through satellite image interpretation. Cianjur Regency and the surrounding areas are areas that are prone to have earth movement disasters. Almost 80% of villages in Cianjur have the potential to have the earth movement disaster with the high earth movement prone zone of 17.24% out of the whole areas of Cianjur Regency (source: Map of Earth Movement Prone Zone-Centre for Volcanology and Geological Disaster Mitigation). The aim of this research is to identify scarp form and to delineate areas which are potential to have earth movement in Cianjur Regency and surrounding areas. The method used in this study is visual interpretation on images as the result of fusion between Landsat 7 and DSM TerraSAR-X, and validating scarp formed locations with location points of earth movement (from BPBD of Cianjur Regency) and Map of Earth Movement Prone Zone-Centre for Volcanology and Geological Disaster Mitigation. The research result shows that most of scarp forms are indications of areas of earth movement. Besides scarp morphology, another geomorphology form like volcanic fan is also potential to have earth movement which need to be considered. Areas of potential to have earth movements around the scarp can be used to revise the Map of Earth Movement Prone Zone and for landuse planning. Data of remote sensing image, especially DSM of TerraSAR-X image with moderate resolution of about 9 m, can be used as basic data to identify scarp form and earth movement zone caused by the morphology form.Keywords: scarp, earth movement, Cianjur, Landsat 7, Terra SAR-X
Vulkanisme dan prakiraan bahaya Gunung Api Anak Ranakah, Nusa Tenggara Timur Deden Wahyudin
Jurnal Lingkungan dan Bencana Geologi Vol 3, No 2 (2012)
Publisher : Badan Geologi

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (792.816 KB) | DOI: 10.34126/jlbg.v3i2.39

Abstract

ABSTRAKGunung Anak Ranakah (2247,5 m dpl) adalah gunung api termuda yang baru lahir pada 28 Desember 1987, terletak di Kabupaten Manggarai, Flores, Provinsi Nusa Tenggara Timur. Gunung api muda ini muncul di antara pegunungan Mandosawu dan Ranakah yang sebelumnya diketahui sebagai kompleks gunung api yang sudah tidak aktif. Berdasarkan batuan penyusun Kompleks Gunung Mandosawu-Ranakah dan pola erupsi Gunung Anak Ranakah tahun 1987-1988, karakter, tipe, dan skala erupsi berikut pola penyebaran produk erupsinya di masa mendatang tidak akan jauh berbeda dengan erupsi sebelumnya, kecuali ada perubahan yang sangat drastis. Dengan memperhatikan jenis, volume, dan jarak/pelamparan produk erupsi di masa lalu, erupsi Gunung Anak Ranakah dapat diklasifi kasikan ke dalam erupsi eksplosif dan efusif bertipe Stromboli-Vulkano berskala kecil sampai menengah. Potensi bahaya primer erupsi Gunung Anak Ranakah terdiri atas aliran piroklastika (awan panas), jatuhan piroklastika (lontaran batu dan abu vulkanik), gas beracun, dan aliran lava. Sementara jenis bahaya sekunder adalah guguran batuan dan lahar. Dari potensi bahaya erupsinya, kawasan rawan bencana gunung api Anak Ranakah dapat dibagi menjadi tiga kawasan yaitu Kawasan Rawan Bencana III, II dan I.Kata kunci: Anak Ranakah, gunung api muda, vulkanisme, prakiraan bahayaABSTRACTAnak Ranakah volcano (2247,5 m asl) is the youngest volcano which was born on 28 December 1987, located in Manggarai Regency, Flores, East Nusa Tenggara Province. This young volcano appeared in between Mandosawu and Ranakah Mountains which was formerly known as an extinct volcanic complex. Based on the rock forming of Mandosawu-Ranakah volcanic complex and eruption type of Anak Ranakah volcano in 1987-1988, the character, type, and scale of future eruption could be not much different from the latest eruptions, except there is a substantial change of eruption style. Based on the type, volume, and distribution of the latest eruption products, the eruption of Anak Ranakah Volcano, can be classifi ed as explosive and effusive of small to medium scale of Strombolian-Vulcanian eruption types. The potential primary hazard of Anak Ranakah eruption consists of pyroclastic fl ows (nue ardantes), pyroclastic falls (ballistic trajectory rocks and volcanic ash), poisonous gas and lava fl ows. Meanwhile, the secondary hazards are rock avalanches and lahars. Based on its potential hazards the volcanic hazard of Anak Ranakah can be divided into three volcanic hazard zones namely Volcanic Hazard Zone III, II and I.Keywords: Anak Ranakah, young volcano, volcanism, hazards assessment
Semburan gas dan dampaknya terhadap lingkungan di sekitar Lumpur Sidoarjo Hanik Humaida; Akhmad Zaennudin; N. Euis Sutaningsih; Y. Sulistiyo
Jurnal Lingkungan dan Bencana Geologi Vol 1, No 1 (2010)
Publisher : Badan Geologi

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (967.231 KB) | DOI: 10.34126/jlbg.v1i1.5

Abstract

SARIFenomena lain yang muncul bersama semburan Lumpur Sidoarjo adalah semburan gas. Munculnya semburan gas ini menimbulkan pertanyaan, antara lain, jenis dan dampaknya terhadap lingkungan, terutama bagi pendudduk sekitarnya, untuk menjawab pertanyaan tersebut dilakukan penelitian geokimia. Hasil penelitian menunjukkan bahwa gas yang keluar adalah gas hidrokarbon dengan komposisi utama gas metana (CH4) dan gas karbondioksida (CO2). Berdasarkan jenis dan sumbernya, gas tersebut merupakan gas termogenik yang sumbernya diperkirakan adalah bahanorganik pada level di atas “Oil Window”. Dari nilai isotop menunjukkan bahwa gas tersebut mempunyai tingkat kematangan termal yang cukup. Akibat semburan gas hidrokarbon ditengah-tengah pemukiman penduduk tersebut berdampak pada lingkungan, terutama air. Air sumur penduduk menjadi keruh dan berbau menyengat sehingga tidak dapat dipergunakan untuk kebutuhan sehari hari.Kata kunci: Semburan gas, Sidoarjo, dampak lingkunganABSTRACTAnother fenomenon which is ocurred in the mud extrution of Sidoarjo is gas abruptions. At first that are become a big question. Due to this reason, an investigation of geochemistry of the gases are needed. These results show that gas abruptions are dominated by hydrocarbon gases with the main composition of methane (CH4) and is followed by carbondioxide (CO2). Based on the kind and its source, these gases are thermogenic gas which derived from organic matter above the level of “Oil Window”. The carbone isotope of the hydrocarbon gases show a mature of thermal maturity degree. Gases abruptions which are occurred in the area of a densed population, caused the water of people shallow well become turbid with strong bad smell which could not be used for daily used.Keyword: Outpouring of gas, Sidoarjo, environment impact
KERENTANAN WILAYAH RENCANA TAPAK RDE SERPONG BERDASARKAN NILAI MEAN AMPLIFICATION MIKROTREMOR Marjiyono Marjiyono; Satianegara R.; Setiawan J. H.; Sopyan Y.; Yuliastuti Yuliastuti
Jurnal Lingkungan dan Bencana Geologi Vol 7, No 1 (2016)
Publisher : Badan Geologi

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (386.042 KB) | DOI: 10.34126/jlbg.v7i1.92

Abstract

ABSTRAKLapisan permukaan pada umumnya merupakan lapisan sedimen termuda dan belum terkonsolidasi. Secara fisis, lapisan ini berpotensi memperkuat goncangan gelombang bila terjadi gempa bumi. Karakterisasi geologi permukaan dalam rangka pengembangan wilayah untuk pemukiman, perkantoran, dan sarana vital lainnya sangat diperlukan dalam rangka mengurangi dampak bencana di kemudian hari. Pemetaan nilai faktor penguatan gelombang berdasarkan perhitungan fungsi alih gelombang geser horizontal (SH transfer function) mikrotremor telah dilakukan di sekitar rencana pembangunan tapak RDE (Reaktor Daya Eksperimental), Serpong. Hasil pengolahan data menunjukkan nilai faktor penguatan gelombang berkisar antara 1,21 - 1,77. Daerah rencana lokasi tapak sendiri berada pada nilai faktor penguatan antara 1,4-1,5.Kata kunci: penguatan gelombang, gelombang geser, mikrotremor, tapak RDEABSTRACTSite amplification is generally caused by youngest and unconsolidated sediment surface layers. Physically, these layers potentially strengthen the wave amplification if an earthquake takes place.The surface geology characterization for the purpose of spatial development for settlement, office, and other vital facilities is needed to mitigate the impact of disasters in the future. An amplification factor mapping based on microtremor SH transfer function was perfomed around the experimental power reactor (EPR) site plan, Serpong. The result of data processing shows the amplification factor values ranged from 1.21 to 1.77. The site plan location itself is in the values of between 1.4 to 1.5.Keywords: site amplification, shear wave, microtremor, EPR site
Pengaruh letusan Gunung Sinabung pada 15 September 2013 terhadap pengukuran deposisi asam di SPAG Bukit Kototabang Agusta Kurniawan
Jurnal Lingkungan dan Bencana Geologi Vol 5, No 1 (2014)
Publisher : Badan Geologi

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (6677.495 KB) | DOI: 10.34126/jlbg.v5i1.62

Abstract

ABSTRAKMakalah ini meneliti tentang pengaruh letusan Gunung Sinabung pada 15 September 2013 terhadap pengukuran deposisi asam di Stasiun Pemantau Atmosfer Global (SPAG) Bukit Kototabang, Kabupaten Agam, Provinsi Sumatra Barat. Ada dua jenis deposisi asam yang dikaji yaitu deposisi kering dan deposisi basah. Deposisi kering meliputi pengukuran gas (SO2, NO2, dan O3) dan partikel (PM10 dan TSP). Sedangkan deposisi basah meliputi pengukuran tingkat keasaman (pH) dan daya hantar listrik (DHL) air hujan. Data agregat harian sebelum dan setelah letusan Gunung Sinabung dibandingkan untuk mengetahui adanya indikasi perubahan. Sebagai batas toleransi yang dipersyaratkan digunakan nilai baku mutu udara ambien menurut PP No. 41 Tahun 1999. Hasil analisis menunjukkan bahwa letusan Gunung Sinabung pada 15 September 2013 tidak berpengaruh terhadap pengukuran deposisi asam di SPAG Bukit Kototabang. Simulasi menggunakan model yang datang ke Bukit Kototabang bukan berasal dari Gunung Sinabung. Hysplit Volcanic Ash BMKGNOAA, menunjukkan bahwa arah material letusan Gunung Sinabung ke timur sampai utara dan menyebar menjauh dari Bukit Kototabang. Simulasi pergerakan massa udara menggunakan Model Flextra Backward Trajectory menunjukkan bahwa massa udara yang sampai ke Bukit Kototabang bukan berasal dari Gunung Sinabung.Kata kunci: Gunung Sinabung, Bukit Kototabang, Deposisi Asam, Hysplit Volcanic Ash NOAA-BMKG,Flextra Backward TrajectoryABSTRACTThis paper studied the impact of Mount Sinabung eruption to acid deposition parameters in Global Atmosfer Watch (GAW )Bukit Kototabang Station, District of Agam, West Sumatra Province on September 15th, 2013. Two types of acid deposition were studied: dry and wet deposition. Dry deposition measurement includes the gases (SO2, NO2, and O3) and particles (PM10 and TSP). Meanwhile, wet deposition studied includes acidity level (pH) and rainwater conductivity. Daily average data, before and after the eruption, are compared to find indications of any change.  As tolerance limits used ambient air quality standard value according to PP No. 41 of 1999. Results showed that Mount Sinabung eruption on 15 September 2013 did not show a significant impact on the measurement on the wet and dry deposition parameters. Simulation of volcanic ash trajectory from BMKG-NOAA HYSPLIT Volcanic Ash also suggested that the ash moved east to north, spreading away from Bukit Kototabang. Simulation of air mass movement using backward trajectories Flextra Model showed that air mass arrived to Bukit Kototabang wasn’t from Mount Sinabung.Keywords: Mount Sinabung, Bukit Kototabang, acid deposition, Hysplit Volcanic Ash NOAA-BMKG, Flextra Backward Trajectory
Gempa Bumi Bandung 22 Juli 2011 Cecep Sulaeman; Sri Hidayati
Jurnal Lingkungan dan Bencana Geologi Vol 2, No 3 (2011)
Publisher : Badan Geologi

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (633.89 KB) | DOI: 10.34126/jlbg.v2i3.30

Abstract

SARIPada tanggal 22 Juli 2011 pukul 05.46 terjadi gempa bumi di kawasan kota Bandung. Getaran gempa bumi tersebut terasa di Bojongkoneng, Ujungberung, dan Pasir Impun, Kota Bandung dengan intensitas II – III MMI. Berdasarkan data dari enam stasiun seismik yang ada di Bandung dan sekitarnya telah ditentukan pusat gempa bumi terletak pada koordinat 107,72° BT dan 6,84°LS dengan kedalaman 6 km, berada pada jarak 12,5 km timur Lembang dan 16 km timurlaut Bandung. Lokasi sumber gempa bumi tersebut berada pada jalur Sesar Lembang. Magnitudo gempa bumi tersebut 3,4 Richter dan memiliki mekanisme fokal dengan pergerakan sesar normal.Kata kunci: gempa bumi Bandung, sesar Lembang, 3,4 RichterABSTRACTA felt earthquake occurred on July 22, 2011 at 05:46 am. It was felt in Bojongkoneng, Ujungberung, and Pasirimpun, Bandung City with intensity II – III MMI. Hypocenter of earthquake was obtained from six seismometers installed around Bandung. The earthquake was originated at 107.72°E and 6.84°S with 6 km deep, 12.5 km east of Lembang and 16 km northeast of Bandung. The earthquake source is located at Lembang fault lines. It has a magnitude of 3.4 Richter and normal fault solution.Keywords: Bandung earthquake, Lembang fault, 3.4 Richter
Daya Dukung Tanah Fondasi Dangkal Pada Bukit Hambalang Bagian Selatan, Kecamatan Citeureup, Kabupaten Bogor Rifki Asrul Sani
Jurnal Lingkungan dan Bencana Geologi Vol 8, No 3 (2017)
Publisher : Badan Geologi

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (2603.163 KB) | DOI: 10.34126/jlbg.v8i3.127

Abstract

ABSTRAKSeiring dengan terjadinya longsoran di beberapa titik wilayah di bukit Hambalang, maka diperlukan kajian data kondisi geologi teknik berupa sifat fisik dan mekanik tanah serta batuan bawah permukaan, terutama mengenai daya dukung tanah dalam menahan beban bangunan di atasnya agar tidak terjadi penurunan. Metode yang digunakan dalam penelitian ini dibagi menjadi tiga, yaitu metode penelitian studio dengan memanfaatkan data-data sekunder yang telah ada, metode penelitian di lapangan melalui pemetaan geologi untuk mendapatkan data litologi yang tersingkap di permukaan, zonasi longsoran yang terjadi, dan identifikasi kekuatan tanah hasil pemboran geoteknik dengan Standard Penetration Test (SPT), serta metode penelitian di laboratorium untuk mendapatkan parameter sifat fisik dan mekanik tanah sebagai penunjang data daya dukung tanah serta geologi teknik daerah penelitian. Hasil perhitungan fondasi dangkal untuk general soil shear condition dan local soil shear condition dapat disimpulkan bahwa daya dukung tanah yang diizinkan (qa) untuk setiap kedalaman yang paling tinggi pada fondasi bujur sangkar (square footing) dan nilai tertinggi yang terdapat pada kedalaman 2 m, yaitu 57,32 ton/m2 dan 36,11 ton/m2. Fondasi yang paling rendah untuk semua kedalaman pada fondasi menerus (continuous footing) untuk kedalaman 2 m memiliki nilai 34,49 ton/m2 dan 21,25 ton/m2. Berdasarkan data SPT, nilai daya dukung yang diizinkan (qa) pada masing-masing titik bor berkisar pada rentang 2,85 ton/m2 sampai 16,85 ton/m2. Kata kunci: longsoran, daya dukung, Standard Penetration Test (SPT). ABSTRACTAlong with the landslide in some areas on the Hambalang Hill, it needs data of engineering geological study such as mechanical and physical properties of soil also subsurface rocks. Especially regarding the soil bearing capacity in order to restrain the building from settlement. There are three methods which used in this research, those are studio research by using secondary data, fieldwork research that is geological mapping conducted to obtain data on lithological rocks at surface, landslide zone and soil strength identification from geotechnical drilling with Standard Penetration Test (SPT) and laboratory research to obtain the soil parameters of physical and mechanical properties, which used to support soil bearing capacity data and engineering geology in research area. The calculation results of the shallow foundation for general soil shear condition and the local soil shear condition it could be concluded that the allowable bearing capacity for all depth which is highest at the square footing and the highest value found to a depth of 2 m, that is 57.32 ton/m2 and 36.11 ton/m2. The lowest foundation for all the depth of the continuous footing to a depth of 2 m had value 34.49 ton/m2 and 21.25 ton/m2. Based on data from SPT, the allowable bearing capacity on each of borehole ranging from 2.85 ton/m2 to 16.85 ton/m2. Keywords: landslide, bearing capacity, Standard Penetration Test (SPT).
The behaviour of fluorine, chlorine, and sulphur in the magma of Merapi Vulcano Central Java – Indonesia E. Kadarsetia; J. Hirabayashi; T. Ohba; K. Nogami
Jurnal Lingkungan dan Bencana Geologi Vol 1, No 3 (2010)
Publisher : Badan Geologi

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (2023.705 KB) | DOI: 10.34126/jlbg.v1i3.20

Abstract

ABSTRACTMerapi volcano, located at Central Java - Indonesia, is one of the world’s most active volcano. In order to gain better understanding on volcanism and magmatism of this calc-alkaline volcano, various researches have been carried out. Some valuable information concerning volcanism of Merapi volcano can be indirectly obtained through the investigation of fluorine, chlorine and sulphur behavior in the magma. To accomplish this study, sixteen rock samples have been taken from the summit. Petrographic and chemical analysis of the rocks had been carried out. Major elements composition, analyzed by X-ray fluoresence method, shown that during the last 100 years chemical composition of magma have not been significantly changed, about 55 wt% of SiO2. Chemical composition of individual minerals, determined by EPMA, suggested a constant composition the magma. Bulk compositions of fluorine and chlorine were determined by wet analytical methods, Ion-selective Electrode “by Trymethylsilylating distillation” method and spectrophotometer determination by Mercury Thiocyanate method respectively. On the other hand, sulphur was determined by a fluorescence instrumental method. The concentration of fluorine, chlorine and sulphur are 210 - 390 ppm, 60 - 540 ppm (water insoluble) and 17 - 82 ppm respectively. The relationship between Cl with Si02 and CaO could be observed. F in agreement with CaO, and in general correlate with the volume of hydrous minerals. Most of F/Cl atomic ratio of Merapi rocks >1, and decrease with increasing Si02, or F is more reactive than Cl to the magma, especially in the earlier stage of crystallization. The equal size of fluorine and hydroxyl ions permits fluorine to substitute easily for OH- in hydrous minerals or melt, Cl may be expelled during crystallization when in the fluorine present. In more residual magma the larger ionic radius of chlorine and its renown ability to form complex molecules should lead to greater concentration of chlorine than fluorine; these facts as well as the water solubility of chlorine compounds, that have been advanced as an explanation for the high Cl/F ratio obtained in volcanic gases. Sulphur has parallel correlation with FeO. It is shown that sulphur was more partioned into Fe rich magma, whereas Fe-S mineral is more likely. Therefore, the low sulphur content of Merapi lava might be as the characteristics of island arc volcanism.Keywords: Composition magma of Merapi, chlorine, fluorine, sulphur
Analisis Kerentanan Longsoran Menggunakan Proses Hirarki Analitik di Daerah Sukatani dan Sekitarnya, Kabupaten Purwakarta, Jawa Barat Landslide Susceptibility Analysis Using Analytic Hierarchy Process In Sukatani And Its Surroundings, Purwakarta Regency, West Java Misbahudin Misbahudin; Abdullah Husna; Rusdi Toriq; Agus Marwantho
Jurnal Lingkungan dan Bencana Geologi Vol 8, No 1 (2017)
Publisher : Badan Geologi

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (9747.603 KB) | DOI: 10.34126/jlbg.v8i1.167

Abstract

ABSTRAKDaerah penelitian terletak di wilayah Sukatani dan sekitarnya, Kabupaten Purwakarta, Jawa Barat. Daerah tersebut memiliki kondisi geomorfologi yang berbukit-bukit akibat pengaruh produk vulkanik berupa lahar, aliran piroklastika, dan intrusi. Pada daerah tersebut terdapat laporan mengenai longsoran yang terjadi di beberapa lokasi dekat tempat tinggal penduduk. Atas dasar tersebut, peta kerentanan longsoran dibuat untuk memberikan informasi mengenai persebaran tingkat kerentanan longsoran pada daerah penelitian. Peta yang digunakan sebagai dasar pembuatan adalah peta sebaran litologi, struktur geologi, kemiringan lereng, relief relatif, kebasahan lahan, dan tutupan lahan. Parameter tersebut dikelaskan berdasarkan faktor evaluasi bahaya longsoran. Tingkat kerentanan terhadap longsoran diperoleh dengan metode proses hirarki analitik dan pengujian rasio konsistensi. Tahapan penggabungan peta menggunakan cara tumpang susun. Secara umum, peta kerentanan longsoran yang telah dibuat menunjukkan korelasi yang baik sesuai dengan kondisi di lapangan. Tingkat kerentanan sangat rendah meliputi 43% daerah penelitian, tingkat kerentanan rendah meliputi 40,5% daerah penelitian, tingkat kerentanan sedang meliputi 14,5% daerah penelitian, dan tingkat kerentanan tinggi meliputi 2% daerah penelitian. Kemiringan lereng adalah kontrol utama faktor-faktor penyebab longsoran di daerah penelitian. Zona kerentanan menengah hingga tinggi umumnya berada pada lereng terjal dengan material berupa breksi piroklastika.Kata kunci: Kerentanan longsoran, proses hirarki analitik, Purwakarta, SukataniABSTRACTThe researched area is located in Sukatani and surrounding areas, Purwakarta, West Java. The area has a hilly geomorphological condition due to the influence of volcanic products in the form of lava, pyroclastic flows, and intrusion. In that area there are reports of landslide that occurred at several locations near residences. On that basis, a landslide susceptibility map was made to provide information about the distribution of susceptibility level of landslides in the researched area. Maps which are used as the basis are maps of lithology, structural geology, slope, relative relief, soil wetness, and land cover. Those parameters are classified based on the landslide hazard evaluation factors. Landslide susceptibility index was obtained by using the method of analytic hierarchy process and by testing the consistency ratio. Stages for merging maps used the overlaying method. In general, a landslide susceptibility mapthat has been made shows a good agreement with conditions in the field. The level of very low susceptibility covered 43% of the studied area, the low level covered 40.5%, the medium level covered 14.5%, and the high level included2% of the researched area. A slope is the main control of factors that cause landslides. Medium to high susceptibility zones are generally on steep slopes with pyroclastic breccia materials.Keywords: Analytic Hierarchy Process, landslide susceptibility, Purwakarta, Sukatani

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