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"ABSTRAKThe lahar flow that occurred after the 2012 Gamalama Volcano eruption, leading to the eastern valley flowing downstream through the Togurara River to the center of Ternate City and Sultan Babullah Airport. To overcome the potential of lahar flow in the river since 2013 - 2016, several sabo dams and building facilities have been built. Based on the results of the calculation of deposits that potentially become lahar flows in 2016, the built-in capacity of the Sabodam has not been able to control the volume of sediment in the upstream of the river, then in the year 2017, 2018 constructed several additional Sabodam. In order to determine the effectiveness, feasibility and conditions of the completeness of Sabodam, is done field assessment on 25 ~ 27 September 2018, the method used was a mathematical approach based on sabo technology. The assessment was in the form of a field survey, simple measurements, interviews with the Sabodam management agency and local residents related to the lahar flow that had occurred. With the capacity of several additional Sabodams built in series, the average river bed slope was originally 9.09% to 6.83%. After the construction of Sabodam, the maximum lahar flow was once as high as 7 m, but now it decreases do 4.2 m. As the slope of the Togurara River slopes progressively, the lahar flow rate and its destructive power are reduced, so that Ternate City and Sultan Babullah Airport are spared from lahar disaster."

" ABSTRAKPenelitian ini membahas tingkat kerentanan wilayah terhadap bencana letusan Gunungapi Guntur dengan faktor penentu kerentanan berupa keadaan sosial ekonomi. Daerah penelitian merupakan kawasan rawan bencana letusan Gunungapi Guntur yang didapat dari pemetaan kawasan terdampak letusan terakhirnya pada tahun 1847 masehi, dengan satuan unit analisis berupa desa/kelurahan. Metode penelitian yang digunakan adalah metode Social Vulnerability Index (SoVI) yang merupakan metode penelitian kuantitatif dalam penelitian kerentanan sosial. Metode ini mengonversi data-data sosial ekonomi wilayah ke dalam angka-angka, yang selanjutnya diolah untuk mendapatkan tiga kelas pembobotan: tinggi, sedang, dan rendah. Hasil pengolahan data sosial ekonomi dianalisis secara spasial dengan pembanding berupa data penggunaan tanah. Berdasarkan analisis dari hasil pengolahan data sekunder dan hasil survei lapang, desa dengan tingkat kerentanan tinggi dan sedang terletak pada daerah dengan dominasi penggunaan tanah berupa pertanian yang memiliki tingkat kesejahteraan sosial rendah. Desa dengan tingkat kerentanan rendah terdapat pada daerah dengan dominasi penggunaan tanah berupa kawasan terbangun yang memiliki kesejahteraan sosial tinggi.

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ABSTRACT

This study about area vulnerability level of Guntur Volcano eruption based on its social economy condition, a social vulnerability. The research area is the entire village that listed as disaster-prone area of Guntur Volcano based on its latest eruption in 1847 AD. Social Vulnerability Index (SoVI) is used as a quantitative method in area vulnerability studies to calculate the social vulnerability level in each village. SoVI convert eight type social economy data into numbers and classify it into three classes that represent the vulnerability level for each village, those classes are: high, moderate, and low. Furthermore, those classified data are analyzed spatially by land use in each village. The analysis result shows that areas with high and moderate vulnerability level are those villages that dominated by agriculture and commonly have a low social welfare. Areas with low vulnerability level are those constructed village and commonly have a high social welfare."

"Kompleks Gunungapi Rawa Danau berada di Provinsi Banten terbentuk akibat letusan dari gunungapi purba. Tersusun atas lava yang berumur kuarter berasal dari Gunung Karang, Gunung Parakasak, Gunung Tukung Gede, Gunung Marikangen dan Gunung Dano Purba yang berkaitan dengan subduksi lempeng Indo-Australia dan Eurasia di selatan Pulau Jawa. Tujuan dilakukannya penelitian ini untuk mengetahui jenis dari lava penyusun gunungapi, mengetahui evolusi magma serta tatanan tektonik pada daerah penelitian. Penelitian ini menggunakan metode petrografi dan geokimia dengan analisis X-ray Fluorescence (XRF). Daerah penelitian terdiri dari mineral plagioklas, piroksen, olivin, dan amfibol serta terdapat mikro-tekstur plagioklas berupa coarse sieve, glomerocryst, oscillatory, fine sieve, dan clear. Jenis batuan yang berada di daerah penelitian adalah andesit-basaltik, basaltik trachyandesite, andesit, trachyandesite, dasit, dan trachyte trachydacite. Daerah penelitian memiliki jenis magma yaitu kalk-alkalin. Berdasarkan diagram Harker, terlihat tren yang jelas sehingga magmanya bersifat ko-genetik. Berdasarkan keberadaan amfibolnya terbagi menjadi 3 tren yaitu tren Gunung Karang yang merupakan amfibol bearing, tren Gunung Parakasak merupakan amfibol free, dan tren Gunung Tukung Gede yang merupakan amfibol free dan amfibol bearing. Proses magmatisme yang dominan terjadi pada daerah penelitian berupa fraksinasi kristal dan Proses tektonik yang terjadi adalah subduksi busur benua yang memiliki kedalaman zona Benioff-Wadati sekitar ±118 Km - ±138 Km.

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The Rawa Danau Volcanoes complex is located in Banten Province. This volcano complex was formed by ancient volcanoes eruptions. It is Composed by quarterly lava originating from Mount Karang, Mount Parakasak, Mount Tukung Gede, Mount Marikangen and Mount Dano Purba which are associated with the subduction zone of the Indo-Australian plate and Eurasian plate in the southern Java. The purpose of this study is to find out the type of lava constituents of this volcano complex, to know the evolution of magma, and the tectonic history of Rawa Danau Volcanoes Complex as the study area. This study uses petrographic method and geochemical methods with X-ray Fluorescence (XRF) analysis. The study area consists of plagioclase, pyroxene, olivine, and amphibole minerals. There are also micro-textures of plagioclase in the form of coarse sieve, glomerocryst, oscillatory, fine sieve, and clear. Divided into two groups of rocks, namely the group of amphibole bearing rocks and amphibole free rocks. The SiO₂ content of this area is 55% to 71%, that is why the rock are andesite-basaltic, basaltic trachyandesite, andesite, trachyandesite, dacite, and trachyte trachydacite. The type of magma is calc-alkaline. Based on the Harker diagram, the study area has a clear trend so that the magma is co-genetic, then that trend is divided into two, namely positive trend and negative trend. However, based on the presence of amphibole mineral, it is divided into three trends, namely Karang trend, which is an amphibole bearing zone, Parakasak trend is an amphibole free zone, and Tukung Gede trend, which is an amphibole free zone and amphibole bearing zone. The dominant process of magmatism in the study area was fractional crystallization and the tectonic processes that occurred was continental arc subduction which had a Benioff-Wadati zone depth of approximately ± 118 Km - ± 138 Km."

"Penafsiran potret udara hitam putih (phanchromatic) tahun 1971 daerah lembah Kerinci dimaksudkan untuk mengidentifikasi elemen morfotektonik, tujuannya untuk mengkaji genesa (tektonika) pembentukan lembah Kerinci dan mendeliniasi zonasi potensi bencana alam. Hasil penafsiran potret udara menunjukkan adanya jejak elemen morfotektonik makro yang berkaitan dengan gerak-gerak tektonik masa lalu, antara lain sejumlah gawir sesar tua, gawir sesar muda, gawir sesar kecil, pergeseran alur sungai, kelurusan lembah dan beberapa bentuk kelurusan lainnya. Bentang alam lembah Kerinci merupakan hasil kegiatan struktur yang didominasi oleh gerakan vertical. Di samping itu diamati beberapa bentuklahan penyerta gerakan tektonik, berupa tumpukan kipas alluvial gunungapi dan endapan undak. Pola gawir sesaran tersebut membentang sejajar arah Pulau Sumatera dan akhirnya menyempit di bagian utara. Di wilayah ini sangat berpotensi menjadi gempa bumi. "

"Penggunaan energi yang effisien menjadi tantangan dunia saat ini untuk terus ditingkatkan. Berbagai metode terus dikembangkan oleh para peneliti dan ilmuan untuk mencapai apa yang diharapkan. Dalam sistem perpipaan, energi dibutuhkan untuk dapat menggerakkan fluida yang akan dialirkan. Ilmu mekanika fluida berperan penting untuk dapat mengkarakteristik  fluida saat mengalir. Secara umum fluida dibagi menjadi dua kelompok yaitu fluida Newtonian dan non-Newtonian.  Fluida dapat dapat mengalir dengan effisien dalam sistem perpipaan ketika hambatan dapat diatasi. Kerugian energi yang dibutuhkan untuk memindahkan fluida disebut kerugian jatuh tekanan. Singkatnya, sumber energi pompa untuk sistem perpipaan sebanding dengan hambatan dan fluida yang dialirkan. Pengurangan hambatan dapat dilakukan melalui kontrol aliran yang dibagi menjadi dua kelompok yaitu kontrol aktif dan kontrol pasif. Kontrol aktif diaplikasikan dengan cara menambahkan zat aditif sedangkan kontrol pasif dengan memberi perlakuan melalui geometri saluran perpipaan. Dalam penelitian ini kontrol aktif dan kontrol pasif diaplikasikan. Aplikasi kontrol aktif dengan menambahkan aditif serat nata de coco ke dalam fluida dasar air dan kontrol pasif dengan menggunakan pipa spiral 3-lobe untuk mengalirkan lumpur. Aplikasi serat nata de coco sebagai aditif untuk dapat mereduksi hambatandrag pada buffer region. Konsentrasi yang digunakan ialah 25 ppm, 50 ppm dan 100 ppm yang dialirkan pada rangkaian uji pipa horizontal dengan pengukuran nilai pressure drop pada jarak 1000 mm. Selain itu, aplikasi pipa spiral 3-lobe untuk mengatasi pengendapan aliran lumpur melalui kecepatan tangensial yang dihasilkan oleh geometri pipa spiral itu sendiri. Fluida kerja lumpur yang digunakan dalam penelitian ini divariasikan dalam beberapa konsentrasi yakni Cw 20%, 30% dan 40%. Fluida kerja yang dialirkan melalui sistem perpipaan disetup secara horizontal serta pengukuran 'pressure drop' melalui dua titik dengan jarak 1550 mm. Untuk pengujian debit pada dua metode ini digunakan untuk menghitung bilangan Reynolds. Dari hasil perhitungan diketahui bahwa aplikasi serat 'nata de coco' pada pipa dapat meningkatkan pengurangan hambatan 'drag' melalui mereduksi 'drag' yang terjadi pada 'buffer layer'. Selain itu, aplikasi pipa spiral untuk mengalirkan lumpur terbukti menurunkan kecepatan kritis pada aliran jika dibandingkan dengan pipa bulat.

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The efficient use of energy is a challenge for the world today to increase continuously. Various methods continue to be developed by researchers and scientists to increase the expected. In the piping system, the energy needed to flow the fluid. Fluid mechanics plays an important role in being able to characterize fluid flow. In general, fluids divided into two groups, namely Newtonian and non-Newtonian fluids. Working fluid will be flow efficiently in the piping system when obstacles can be overcome. Energy losses needed to flow the fluid is called the pressure drop. In brief, the energy source of the pump for the piping system is proportional to the obstacles and the streamed fluid. To reduce the obstacles, flow control is used and divided into two groups namely active control and passive control. Active control is applied by adding additives while passive control by treats or change the geometry of the pipeline channel. In this study, active control and passive control applied. Active control by adding nata de coco fiber additive becomes based fluid and passive control by using a 3-lobe spiral pipe to flow the slurry. The application of nata de coco fiber as an additive can reduce drag resistance in the buffer region. The concentrations used are 25 ppm, 50 ppm, and 100 ppm, which are flowed in the horizontal test pipe circuit by measuring the pressure drop at a distance of 1000 mm. In addition, the 3-lobe spiral pipe application to overcome the particle deposition in mudflow through tangential velocity generated by the geometry of the spiral pipe. The working fluid used in this study varied in several concentrations namely Cw 20%, 30%, and 40%. The working fluid that flowed through the piping system set up horizontally and the measurement of pressure drop through two points with a distance of 1550 mm. The mass flow rate testing on both methods used to calculate Reynolds numbers. From the calculation results, it is known that the application of nata de coco fiber in pipes can increase the drag reduction by reducing the drag that occurs at the buffer region. Also, the application of 3-lobes spiral pipe to flow the slurry has been shown to reduce the critical velocity inflow when compared to circular pipes."

"Gunung Agung is a stratovolcano type of volcano which has a height of 3,142 masl and is located in Karangasem Regency, Bali Province. At the end of 2017, Mount Agung's volcanic activity increased until it finally erupted several times in October to December. The government has prepared refuge pockets at the foot of Mount Agung, in areas that are not directly affected by eruption. There are 19 drilling plan points that will be carried out to meet the raw water needs at the evacuation site. This paper presents the groundwater recharge potential including the distribution of water sources, Hydrogeological conditions and the magnitude of groundwater recharge potential at hillside of Mount Agung and the surrounding area. The method used in this study is a field survey, calculation of potential recharge, analysis and evaluation of hydrogeological conditions, distribution of water sources and calculation of potential groundwater recharge. Groundwater at the foot of Mount Agung has the potential to be utilized and developed mainly to cover raw water needs in several refugee locations, namely in the Districts of Sidemen, Abang and Karangasem. The result of the analysis is that the largest groundwater potential is in Kubu Sub-District, namely 97,560,207 m3 / year, with a position that is relatively susceptible to primary hazards and secondary to Mount Agung eruption. For locations that are relatively safe and reachable in the area, they are in Tianyar, Sukadana, Baturinggit, Kubu, and Tulamben Villages, all of which are on the coast of the sea. These results are expected to be used by local governments in an effort to deal with the provision of water from the impact of the eruption of Mount Agung."