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Analytic Hierarchy Process pada Evaluasi Kejadian Longsor di Kecamatan Samigaluh Kulon Progo, D.I. Yogyakarta Apriani, Ani; Putra, Bayurohman Pangacella; Alfariji, Moh.; Habib, Juhair Al; Trisnaning, Paramitha Tedja
Jurnal Lingkungan dan Bencana Geologi Vol 13, No 2 (2022)
Publisher : Badan Geologi

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.34126/jlbg.v13i2.403

Abstract

ABSTRAK Kondisi geografis Indonesia yang heterogen dengan kemiringan cukup tinggi menjadi potensi terjadinya bencana tanah longsor. Meskipun tanah longsor terjadi juga karena faktor yang memicu seperti curah hujan dan tata guna lahan. Daerah yang kerap terjadi tanah longsor yaitu Kecamatan Samigaluh Kabupaten Kulon Progo. Menganalisa penyebab terjadinya tanah longsor di daerah tersebut menjadi penting dilakukan agar penanganan dan pengendalian dilakukan sedini mungkin. Faktor pengontrol yang dianalisa yaitu kelerengan, litologi, kerapatan vegetasi dan jenis tanah sedangkan faktor pemicu yaitu curah hujan dan tata guna lahan. Tujuan dari penelitian ini untuk mengetahui seberapa besar faktor pengontrol dan pemicu tersebut terhadap terjadinya tanah longsor di Kecamatan Samigaluh Kabupaten Kulon Progo. Penelitian melalui beberapa tahapan yaitu pengambilan data primer dilapangan dan data sekunder yang didapatkan dari peta rupa bumi Indonesia, peta geologi dan pengolahan citra landsat. Analisa data dilakukan secara kuantitatif menggunakan AHP (Analytical Hierarchy Process). Hasil penelitian menunjukkan bahwa faktor kelerengan menjadi penyebab terbesar terjadinya tanah longsor di Kecamatan Samigaluh yaitu 33,3%, curah hujan 22,8%, litologi 17%, tata guna lahan 11,8%, kerapatan vegetasi 8,8% dan jenis tanah 5,8%. Dengan diketahuinya penyebab terjadinya tanah longsor diharapkan masyarakat lebih berhati-hati dalam pemilihan lahan permukiman serta pemerintah dapat membuat kebijakan tentang pola tata ruang.Kata kunci: AHP, Kelerengan, Samigaluh,Tanah longsor ABSTRACT The heterogeneous geographical condition of Indonesia with a fairly high slope is a potential for landslide disasters. Although landslides also occur due to triggering factors such as rainfall and land use. Areas that often occur landslides are Samigaluh District, Kulon Progo Regency. Analyzing the causes of landslides in the area is important so that handling and control is carried out as early as possible. The analyzed controlling factors were slope, lithology, vegetation density and soil type, while the trigger factors were rainfall and land use. The purpose of this study was to determine how much the controlling and triggering factors for the occurrence of landslides in Samigaluh District, Kulon Progo Regency. The research went through several stages, namely primary data collection in the field and secondary data obtained from Indonesian topographic maps, geological maps and landsat image processing. Data analysis was carried out quantitatively using AHP (Analytical Hierarchy Process). The results showed that the slope factor was the biggest cause of landslides in Samigaluh District, namely 33.3%, rainfall 22.8%, lithology 17%, land use 11.8%, vegetation density 8.8% and soil type 5,8%. By knowing the causes of landslides, it is hoped that people will be more careful in choosing residential land and the government can make policies on spatial patterns. Keywords: AHP, Slopes, Samigaluh, Landslide
Identification of Paleovolcanic Centers in the Bima District, East Sumbawa Island (Indonesia) as Guidance for Future Exploration of Cu-Au Deposits Habib, Juhair Al; Setijadji, Lucas Donny; Maryono, Adi; Rompo, Iryanto
Journal of Applied Geology Vol 9, No 1 (2024)
Publisher : Geological Engineering Department Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/jag.98713

Abstract

The formation of Cu-Au mineralization, such as porphyry and epithermal deposits, is strongly associated with volcanic processes in specific tectonic settings, such as subduction zones. The identification of the presence of ancient volcanoes is one of the important steps to finding mineral deposits. This study aims to identify the presence of ancient volcanoes in the Bima District, eastern part of Sumbawa Island, as a step toward determining the potential indication of Cu-Au mineralization. The methods used in this research consist of a literature study, image analysis and remote sensing, field survey and data collection, and petrographic analysis. Image analysis using DEMNAS (Digital Elevation Model), including texture and pattern analysis using the concept of volcanic anatomy, aims to identify the remaining forms of ancient volcanoes. Field surveys and data collection include volcano geomorphology, lithology and sampling, and also geological structures. Petrographic analysis is conducted to qualitatively characterize the texture, structure, and mineralogy of volcanic rocks. The identification results show that there are at least ten volcanoes (crown) identified through image analysis, namely Doro Mbangga, Doro Baku, Doro Donggo Masa, Doro Rompo, Doro Sape, Doro Kowo, Doro Jia, Doro Sambori, Doro Mangge, and Doro Lambu. Each of these volcanoes has one or more eruption center (hummock). The eruption center identified in the central, proximal, to distal facies of the volcano, even superimposing one volcano product with another, and spread around 80-90% in the study area. The volcanic facies in the study area are characterized by the central part being composed of lithologies such as intrusive rocks, lava, and diatreme breccia, while the proximal and distal facies are composed of breccia, volcanic breccia, and tuff.  Hydrothermal alteration zones are identified in the central and proximal facies of the volcano. These alterations were associated with the presence of eruption centers, where the abundance of eruption centers means that hydrothermal alterations are particularly well developed and pervasively formed. Identified argillic and advanced argillic alteration associated with stockworks forming a lithocap environment. In addition, the presence of intrusive rocks such as diorite and dacite with chloritic and sericitic alteration in the central facies of Doro Baku can be associated with the presence of deposits such as porphyry and epithermal, so the identification of ancient volcanic eruption centers in the Bima district has implications for the potential discovery of Cu-Au mineralization, such as porphyry and epithermal deposits.