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Geologi Kuarter dan Cuaca Daerah Lampung Barat, Kaitannya dengan Kejadian Longsor (Studi Kasus Jalur Jalan Transek Lampung Barat) Iqbal, Prahara
Jurnal Geologi dan Sumberdaya Mineral Vol 19, No 3 (2018): Jurnal Geologi dan Sumberdaya Mineral
Publisher : Pusat Survei Geologi

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (224.803 KB)

Abstract

Deposition characteristic study in the West Lampung transect road based on field observation, soil mechanic analysis, and the weather of west Lampung study have been done to get its relationship to the landslide. The methods were used are geological mapping, laboratory analysis, and Lampung Barat weather data. Lampung Barat is an area with equatorial rainfall type, this type has ≥ 2000 mm of rainfall annually. The geological condition of Lampung Barat transects road illustrates that the area is predominantly composed by clay and sandy tuff that loose, unconsolidated, and high capacity expands characteristic. This condition caused the soil sediments of West Lampung transect road which form slope would be potentially to form landslides through intensely weightiness of rainwater.Keywords: Lampung Barat transect road, equatorial rainfall type, landslide.
Kondisi Geologi dan Pemodelan Kestabilan Lereng Jalur Transek Liwa-Ranau, Liwa, Lampung Barat Iqbal, Prahara; Aribowo, Sonny; Mulyono, Asep; Syahbana, Arifan Jaya
Jurnal Geologi dan Sumberdaya Mineral Vol 18, No 3 (2017): Jurnal Geologi dan Sumberdaya Mineral
Publisher : Pusat Survei Geologi

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Abstract

Landslide investigations and slope stability modeling have been carried out on the Liwa-Ranau transect road, West Lampung, with the aim of finding the relationship between geological conditions and landslide events. The research methods that be used in this investigation are geological mapping, disturbed and undisturbed soil sampling, laboratory analysis, slope stability analysis, and structural geology analysis. The Liwa-Ranau transect road has a hills topography with a NE-SW, north-south, and NW-SE direction and relatively sharp curve lineament. Based on the field observations, there are four points of landslides which are distributed in the middle of the transect road. Result of field observation shows soil translational slides and debris flow slides which developed with a 12-15 m wide, 15-55 m height, and 37-75 o slope angle. The sliding soil and rock types consist of sandy tuff, clay soil, and claystone.Keywords: Liwa-Ranau transect road, West Lampung, landslide, slope stability modeling, clay soil, sandy tuff
EVALUASI CADANGAN MINYAK ZONA A DAN B, LAPANGAN RAMSES, BLOK D, MELALUI PEMODELAN GEOLOGI BERDASARKAN DATA PETROFISIKA Iqbal, Prahara; Mardiana, Undang
Teknologi Indonesia Vol 32, No 1 (2009)
Publisher : LIPI Press

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14203/jti.v32i1.55

Abstract

Geology modelling has been done in Zone A and B, Ramses field, Blok D. The modelling was conducted by determining Zone A and B as zone having to be checked based on gamma ray, resistivity, and densitiy curve integrity reading (qualitative analysis) and petrophysic analysis which used GS software (quantitative analysis). Then the data were entered into IRAP RMS 7.3 software. The results are Zone A and B geology modelling and also oil concentration modeling which describe the biggest area of oil concentration, plus the oil amount. the result showed that, the biggest area of oil concentration is at south of each zone. The oil amount are: Zone A=82,78 million barrel, Zone B=36.08 million barrel.
Perbandingan pemodelan respon spektra menggunakan analisis discreet point dengan standar perencanaan ketahanan gempa untuk bangunan gedung dan non gedung tahun 2010 (Studi kasus Kecamatan Cilacap Selatan, Kota Cilacap, Provinsi Jawa Tengah) Arifan Jaya Syahbana; Prahara Iqbal
Jurnal Lingkungan dan Bencana Geologi Vol 5, No 2 (2014)
Publisher : Badan Geologi

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (2750.694 KB) | DOI: 10.34126/jlbg.v5i2.69

Abstract

ABSTRAKPemodelan respon spektra berdasarkan metode Discreet Point dan Standar Perencanaan Ketahanan Gempa Untuk Bangunan Gedung dan Non Gedung Tahun 2010 telah dilakukan dengan mengambil lokasi di Kecamatan Cilacap Selatan, Kota Cilacap, Provinsi Jawa Tengah. Pengeboran teknik dilakukan di dua titik di Kota Cilacap, yaitu BH-02 dan BH-03 untuk mengetahui stratigrafi tanah dan karakteristik fisik tanah daerah penelitian. Studi mengenai respon spektra mutlak dilakukan terutama pada daerah dengan nilai ekonomi dan sosial yang tinggi. Hal ini guna mengantisipasi kegagalan struktur bangunan saat gempa bumi terjadi. Metode yang dilakukan pada studi ini adalah Discreet Point. Metode ini menganggap tanah akan menjadi beban pada suatu sistem pemodelan di tengah lapisan. Input yang dimasukkan adalah Gempa Bumi Chichi, Kobe, dan Kocaeli. Alasannya adalah adanya kesamaan mekanisme dengan gempa bumi yang melanda Kota Cilacap pada tahun 2011. Hasil penelitian memperlihatkan bahwa: input gempa bumi yang mempunyai karakteristik percepatan sama dapat menghasilkan respon spektra yang berbeda apabila durasi efektif gempa bumi berbeda, daerah Cilacap pada titik BH-02 dan BH-03 mengalami deamplifikasi apabila ditinjau menggunakan Standar Perencanaan Ketahanan Gempa Untuk Bangunan Gedung dan Non Gedung (ditulis: SPKGUBG&NG) 2010, sedangkan penelitian ini menghasilkan deamplifikasi untuk lokasi BH-02 dan amplifikasi yang kecil pada lokasi BH-03. Hasilnya, lokasi BH-02 percepatan di batuan dasar dari 0,457g menjadi 0,33g sedangkan lokasi BH-03 dari 0,462g menjadi 0,51g.Kata kunci: Discreet Point, SPKGUBG&NG 2010, respon spektraABSTRACTComparison of response spectra based on modeling method of Discreet Point and Building and Non-Building Earthquake Resistance Planning Standards 2010 has been conducted in South Cilacap District, Cilacap City, Central Java Province. Drilling technique was carried out at two locations in Cilacap City, named BH-02 and BH-03, to know soil stratigraphy, sampling, and physical characteristics of the research areas. Study on response spectra is should be conducted absolutely mainly at the areas of high economic and social values. This study is is carried out to anticipate structural failures when earthquake occurs. The Mmethod applied in this study is Discreet Point. This method assumes that soils will become the load on a modeling system in the middle of the layer. Earthquake inputs applied in the simulation are Chichi, Kobe, and Kocaeli. The reason is that there is similarity in mechanism with the one that hit Cilacap City in 2011. Research results show that: earthquake inputs that have the same acceleration characteristics can result in different response spectra when effective duration of the earthquake is different, the Cilacap area at BH-02 and BH-03 experienced deamplification when viewed using SPKGUBG&NG 2010, while this study resulted in unamplification to the location of BH - 02 and a small amplification at location BH – 03. In this study, the acceleration at BH-02 the bedrock was unumplified from 0, 457g to become 0, 33g, while at location of BH-03 it underwent umplification from 0, 462g to 0, 51g. The result shows that at location of BH – 02 the acceleration in the bedrock which was 0,457g became 0,33g, whereas at location BH – 03 which was of 0,462g became 0,51g.Keywords: Discreet Point, SPKGUBG&NG 2010, response spectra
Pemodelan Hidrologi Longsoran di Lereng Km 1, Jalur Lintas Barat Liwa - Krui, Lampung Barat Prahara Iqbal; Asep Mulyono; Arifan Jaya Syahbana
Jurnal Lingkungan dan Bencana Geologi Vol 7, No 2 (2016)
Publisher : Badan Geologi

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (883.443 KB) | DOI: 10.34126/jlbg.v7i2.95

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ABSTRAKKejadian longsoran di jalur lintas barat Liwa - Krui sering terjadi yang menyebabkan putusnya jalur perekonomian antar- daerah. Longsoran yang terjadi dominan berjenis longsoran translasi tanah yang diakibatkan oleh infiltrasi airhujan. Pemodelan hidrologi di salah satu lereng jalur lintas barat Liwa - Krui Km 1 telah dilakukan dengan tujuan untuk mengetahui proses terjadinya longsoran dan untuk memilih solusi penanggulangan yang tepat. Metode yang digunakan adalah pemetaan geologi, analisis geoteknik, dan pemodelan hidrologi. Pemodelan hidrologi dilakukan dengan simulasi numerik yang menggunakan data laboratorium. Hasil analisis menunjukkan bahwa longsoran yang terjadi di lereng jalur lintas barat Liwa - Krui Km 1 adalah longsoran translasi dangkal yang disebabkan oleh penjenuhan tanah akibat infiltrasi air hujan. Penanggulangan yang dapat dilakukan untuk mengatasi masalah tersebut adalah dengan memasang lapisan impermeabel berupa lapisan semen.Kata kunci: jalur lintas barat Liwa - Krui, longsoran, pemodelan hidrologiABSTRACTLandslide phenomena at Liwa - Krui west cross road oftenly occur causing loss of inter-regional economic lines. The landslide type predominantly is soil translational slide, caused by rain water infiltration. Slope hydrological modeling at Liwa - Krui west cross road Km 1 was conducted with purposed to determine the occurrence of landslide and choose the right mitigation solution. The methodology used consists of geological mapping, geotechnical analysis, and hydrological modeling. Hydrological modeling was carried out by numerical simulation using laboratory data. The analysis show that the landslide on the Liwa - Krui west cross road slopes is translational shallow landslide, triggered by the soil saturation due to rainfall infiltration. The mitigation method that can be applied to overcome this problem is to place an impermeable layer such as cement on the slope face.Keywords: Liwa - Krui West Cross road, landslide, hydrological modeling
Fasies sedimen Kuarter berpotensi likuifaksi Pesisir Kota Padang, Provinsi Sumatra Barat berdasarkan data inti bor dan CPTu Prahara Iqbal; Adrin Tohari; Imam A. Sadisun; Dwiharso Nugroho
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 (5817.602 KB) | DOI: 10.34126/jlbg.v5i1.61

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ABSTRAKKajian fasies dan sifat fisik sedimen Kuarter kaitannya dengan potensi likuifaksi di daerah Pesisir Kota Padang dan sekitarnya dilakukan dengan tujuan mendapatkan hubungan antara fasies dan karakteristik fisik sedimen Kuarter terhadap potensi likuifaksinya. Metode yang digunakan adalah observasi inti bor dan pola kurva CPTu untuk menentukan fasies yang berkembang, analisis laboratorium, dan analisis potensi likuifaksi untuk mengetahui karakteristik fisik setiap fasies. Berdasarkan asosiasi litologi, pengamatan pola kurva CPTu, analisis laboratorium, dan analisis potensi likuifaksi, terdapat tiga fasies yang berkembang di daerah penelitian dengan potensi likuifaksi yang berbeda. Fasies pasir fluvial memiliki potensi likuifaksi yang lebih tinggi daripada fasies pasir pematang pantai dan fasies lempung rawa, sedangkan fasies lempung rawa memiliki potensi likuifaksi yang paling rendah di antara fasies-fasies tersebut.Kata Kunci: Fasies sedimen Kuarter, CPTu, Likuifaksi, Kota PadangABSTRACTThe study of Facies and physical property of Quaternary sediments and its relationship with liquefaction potential was conducted at the coastal area of Padang city, West Sumatra Province in order to get the relationship between facies and physical characteristics of the Quaternary sediments and its liquefaction potential. The method used are core and CPTu patterns observations to determine the developed facies, laboratory analysis, and liquefaction potential analysis to determine the physical characteristics of each facies. Based on lithological associations, CPTu pattern observations, laboratory analysis, and liquefaction potential analysis, there are three facies that develop at the research areas with different liquefaction potential. Fluvial sand facies has greater liquefaction potential than the beach ridge sand facies and marsh clay facies, while marsh clay facies has the smallest one among two facies.Keyword: Facies and Quarternary sediments Kuarter, CPTu, liquefaction, city of Padang
Karakteristik Fisik Tanah Longsoran di Jalur Transek Liwa-Bukit Kemuning, Lampung Barat Asep Mulyono; Prahara Iqbal
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 (2044.141 KB) | DOI: 10.34126/jlbg.v6i1.72

Abstract

ABSTRAKJalur transek Liwa–Bukit Kemuning merupakan akses jalan utama menuju beberapa wilayah di Sumatra Selatan, Bengkulu, dan wilayah lainnya di Sumatra. Longsor di lereng sepanjang jalur ini sering terjadi yang mengakibatkan jalan terputus. Penelitian ini bertujuan untuk memetakan sebaran titik potensi longsoran dan mengetahui karakteristik fisik tanah di zona longsoran. Identifikasi ini diharapkan dapat menambah data kebencanaan daerah serta rekomendasi guna peningkatan kewaspadaan terhadap bencana longsoran di sepanjang jalur lintas barat. Longsoran pada jalur transek Liwa-Bukit Kemuning teramati sebanyak empat titik lokasi dan yang berpotensi untuk terjadi longsoran teramati sebanyak dua puluh sembilan titik lokasi. Longsoran terjadi pada Formasi Hulusimpang sebanyak satu lokasi, pada Formasi Ranau sebanyak satu lokasi, dan dua lokasi pada Formasi Gunung Api Kuarter. Karakteristik tanah di jalur transek Liwa-Bukit Kemuning menunjukkan tingkat kompresibilitas pasir halus dan plastisitas tanah lanau yang tinggi dan tergolong pada pasir halus diatomae serta lanau anorganik dengan batas plastis lebih dari 50%. Jenis tanah di daerah ini sangat umum berupa hasil pelapukan material vulkanik dan endapan abu vulkanik. Tipe tanah tersebut rentan terhadap kenaikan tekanan air pori dan perubahan sifat fisik sebagai penyebab faktor utama pemicu terjadinya longsoran.Untuk mengurangi terjadinya longsoran di jalur transek Liwa-Bukit Kemuning diperlukan perbaikan pada proses pemotongan lereng jalan agar lebih landai, penanaman tanaman penutup tanah untuk mengurangi erosi dan jaringan drainase serta mengoptimalkan bronjong atau dinding penahan lereng.Kata Kunci: Longsoran, pemetaan, Jalur transek Liwa – Kemuning, Sumatra.ABSTRACTLiwa-Bukit Kemuning transect road is an access point to some regions in Sumatra main roads such as South Sumatra, Bengkulu, and other regions located in Sumatra. Landslide occurrence on the slopes along the roads often resulted in access disconnecting. This study aims to map the distribution of landslide potential and knowing the soil/rock landslide zone physical properties. This identification is expected to add the disaster data/information and public awareness along the roads. Landslide events at the Liwa - Bukit Kemuning transect road are observed in four locations and there are twenty nine potential locations. Landslide occured in one location at Hulusimpang Formation, one location at Ranau Formation, and two locations at Quaternary Volcanic Formation. The characteristics of the Liwa-Bukit Kemuning transect road soil indicates the level of high soil compressibility and plasticity. This soil is classified as diatomaceous fine sand and inorganic silt with plastic limit of more than 50%. The type of soil in this area is very common as the result of weathering volcanic material and deposition of volcanic ash. The soil types are prone to rise in pore water pressure and changes in physical properties as the main factor for triggering the occurrence of landslide. Efforts to reduce the occurrence of landslide at the Liwa-Bukit Kemuning transect road are gentle slope cutting, planting cover crops to reduce erosion and to optimize the gabion or retaining wall.Keywords: Landslide, mapping, Liwa - Kemuning transect road, Sumatra.
POTENSI DAN KARAKTERISTIK BATUAN SUMBER HIDROKARBON DARI CONTO PERMUKAAN DI DAERAH KARAWANG, JAWA BARAT Praptisih Praptisih; Kamtono Kamtono; Prahara Iqbal
JURNAL RISET GEOLOGI DAN PERTAMBANGAN Vol 23, No 2 (2013)
Publisher : Indonesian Institute of Sciences

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1186.768 KB) | DOI: 10.14203/risetgeotam2013.v23.74

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ABSTRAK Penelitian batuan sumber hidrokarbon yang dilakukan di daerah Karawang bertujuan untuk memperoleh data permukaan endapan klastik berbutir halus serta karakteristik litofasies yang diduga sebagai batuan induk hidrokarbon. Metode yang dipakai adalah penelitian lapangan dan laboratorium. Penelitian lapangan meliputi pengamatan stratigrafi detil dan pengambilan conto batuan. Analisa laboratorium terdiri dari analisa kandungan TOC dan pirolisis Rock Eval. Hasil analisa TOC terhadap 17 conto batulempung yang diambil dari Formasi Jatiluhur menunjukkan nilai berkisar antara sebesar 0,53-2,02%. Tmax delapan  conto sebesar 422o-432oC menunjukkan tingkat kematangan thermal yang belum matang. Delapan conto lainnya masuk dalam kategori matang dengan nilai Tmax sebesar 436o-462oC, sedang satu conto dengan nilai Tmax 467oC menunjukkan kategori pasca matang. Nilai HI berkisar antara 33-143 mg HC/TOC, dan termasuk dalam Fasies D, CD dan C. Berdasarkan nilai tersebut, batuan sumber di daerah penelitian dapat menghasilkan gas dengan kuantitas kecil. Potensi hidrokarbon di daerah penelitian menunjukkan kategori kekayaan material organik rendah hingga menengah, dengan kerogen yang termasuk type II dan III. Kualitas batuan sumber berdasarkan nilai HI termasuk dalam kategori gas prone.