POTENSI DAN KARAKTERISTIK BATUAN SUMBER HIDROKARBON DARI CONTO PERMUKAAN DI DAERAH KARAWANG, JAWA BARAT

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

IZGLAĐENI MREŽNI SEIZMIČKI UČINAK PRIMIJENJEN ZA UPORABU ZEMLJIŠTA, STUDIJA SLUČAJA NA OTOKU KALIMANTAN, INDONEZIJA

Smoothed gridded seismicity is an analysis model in seismicity that allows for the obtaining of a rate based on the b-value and the same magnitude range. The data study has been collected and analyzed from a background source gathered by PusGen, referred to as the PusGen catalogue, with approximately 70 thousand data points. Two software programs (i.e. USGS PSHA and OpenQuake) were utilized in this study, and both programs have been proven as reliable in the creation of the 2017 Indonesia Earthquake Hazard Map. The final steps are to compare the acceleration map results with the Kalimantan Island land-use map and to analyze suitability development planning against potential hazards and earthquake risks. The results stated that: (1) acceleration due to the shallow background earthquake for the Kalimantan region, range from 0.00-0.25g (using USGS PSHA) and 0.0-0.4g (using OpenQuake); (2) meanwhile, based on the deep background earthquake source, the maximum accelerations that occur are 0.15g and 0.25g when using USGS PSHA and OpenQuake, respectively; (3) the utilized of land-use for the current and future years is in line with the results of the acceleration simulation. The study recommends to take into account the seismic aspects in new planning of the capital city, mining and residential areas in order to reduce the existing risks.Izglađeni (filtriran) mrežni seizmički učinak temelji se na analizi seizmičnosti, tj. izračunu vrijednosti b i odgovarajuće magnitude. U studiji su prikupljeni i analizirani podatci pozadinskoga izvora, prikupljeni u PusGen katalogu koji obuhvaća približno 70 000 podataka. Korištena su dva programska paketa koja su ranije pouzdano upotrijebljena kod izradbe karte potresnih rizika Indonezije 2017. godine, odnosno njihovi dijelovi nazvani USGS PSHA i OpenQuake. Završni dio računa bila je usporedba karte ubrzanja s kartom uporabe zemljišta na otoku Kalimantan te analiza daljnjega održivog razvoja s obzirom na opasnosti i rizik potresa. Dobiveni su sljedeći rezultati: (1) sila ubrzanja s obzirom plitke potrese u prostoru Kalimantana mijenja se 0 – 0,25 g (prema USGS PSHA), odnosno 0 – 0,4 g (OpenQuake); (2) temeljem dubokih seizmičkih izvora najveće ubrzanje izračunano je u intervalu 0,15 – 0,25 g (USGS PSHA, OpenQuake); (3) uporaba zemljišta, kako danas, tako i u budućnosti, treba pratiti rezultate simulacija (ubrzanja), za koje je preporučeno da postanu dio urbanoga planiranja glavnoga grada regije, ali i okolnih prostora u kojima se rudari

PROCJENA PODLOŽNOSTI NA KLIZIŠTA INICIRANA POTRESOM: POTRES OD 7,5 MW U 2018. GODINI U PALUU, SULAWESI, INDONEZIJA

A catastrophic Palu earthquake on September 28th, 2018 with Mw 7.5 triggered countless slope failures, generating numerous landslides. This paper presents a practical method for susceptibility assessment of earthquake-induced landslides in the Palu region and the surrounding area. The statistical weight of evidence (WoE) model was used to assess the relationship between landslides induced by seismic motion and its causative factors to determine the susceptibility level and derive an earthquake-induced landslide susceptibility map of this study area. The 1273 landslides were classified into two data series, training data for modelling (70%) and test data for validation (30%). The six selected thematic maps as landslide causative factors are lithology, land use, peak ground acceleration (PGA), and slope (gradient, aspect, elevation). The selection of causative factors considerably influences the frequency of landslides in the area. The result is satisfactory because the AUC value of the chosen model excelled the minimum limit, which is 0.6 (60%). The estimated success rate of the model is 85.7%, which shows that the relevancy of the model is good with the occurrence of landslides. The prediction rate of 84.6% indicates that the applied model is very good at predicting new landslides.Katastrofalni potres koji se dogodio u Paluu 28. rujna 2018. godine, magnitude 7,5 Mw, izazvao je brojne nestabilnosti na padinama, uključujući nastanak velikoga broja klizišta. Ovaj rad predstavlja praktičnu metodu za definiranje procjene podložnosti na klizišta izazvana potresom u regiji Palu i okolnom području. Metoda Weight of Evidence (WoE) korištena je za procjenu odnosa između klizišta izazvanih seizmičkim kretanjem i preduvjeta kako bi se odredila razina podložnosti i izradila karta podložnosti na klizišta izazvana potresom u istraživanom području. 1273 klizišta podijeljena su u dvije serije podataka: podatci za treniranje modela (70 %) i podatci za validaciju modela (30 %). Korišteno je šest odabranih tematskih karata kao faktora koji utječu na pojavu klizišta: litologija, korištenje zemljišta, vršno ubrzanje tla (PGA), nagib padine, orijentacija padine i nadmorska visina. Odabir uzročnih faktora znatno utječe na učestalost klizišta na tom području. Rezultat modela zadovoljavajući je jer je vrijednost AUC odabranoga modela premašila minimalnu granicu koja iznosi 0,6 (60 %). Procijenjena uspješnost modela iznosi 85,7 %, što pokazuje relevantnost modela kod pojave klizišta. Stopa predviđanja od 84,6 % upućuje na to da je primijenjeni model vrlo dobar u predviđanju novih klizišta

THE GREAT SUMATRAN FAULT DEPRESSION AT WEST LAMPUNG DISTRICT, SUMATRA, INDONESIA AS GEOMORPHOSITE FOR GEOHAZARD TOURISM

Two approaches can be taken to understand geotourism, namely the geological approach and the geographical approach. This approach will lead to the creation of new geotourism products, initiatives, and experiences, one of which is geohazard tourism involving faults and earthquakes. To identify geomorphosites, the researchers examined rocks, outcrops, and geomorphology. Then various thematic maps are created using mapping software and other drawing applications to simplify textual material and aid synthesis. A synthesis of all that is then carried out to reconstruct the geological and geomorphological history of the study area. Furthermore, the West Lampung geomorphosite candidate was compared to the worldwide fault and earthquake geomorphosite theme. The Great Sumatran Fault depression landscape can be found in Balak Pekon, Batubrak Regency, and Pekon Padang Dalom, Balik Bukit District, West Lampung Regency. This depression is caused by both endogenous and exogenous factors. The endogenous activity takes the form of sediment from volcanism and fault movement, whereas exogenous activity takes the form of river water erosion. The valley's sediments are ignimbrite tuffs/sandy tuffs that form a cliff morphology with a height of + 75 meters and a trend of Southeast-Northwest. In the case of geotourism, initiatives have grown over time around two complementary approaches (geological and geographic) and the result is a geomorphosite in the geohazard area. One of the areas is the Sumatran Great Fault depression geomorphosite, this area was formed due to the movement of the Sumatran fault which caused the 1908, 1933, and 1994 earthquakes. Situations like these can be used as opportunities to enhance learning about the relationships between people, land use, natural processes, and large-scale events by providing real-life examples, this can be packaged into the form of geohazard tourism

Tropical Volcanic Residual Soil

In West Lampung, Sumatra, Indonesia, tropical volcanic residual soils are formed from weathering of volcanic breccias in hydrothermal alteration areas with a thickness of up to 20 m. This soil has the characteristics of clayey silt, low to high plasticity, brownish-red color, has the potential to swelling, easily eroded, and slide when it is saturated, and contains the minerals kaolinite, halloysite, illite, dickite, nacrite, montmorillonite, despujolsite, hematite, and magnetite. The results showed that this soil can cause corrosion of steel and is widely used by the community as a medium for growing plants and vegetables and as a foundation for infrastructure (for example, houses). The volcanic residual soil of the research area had Low Rare Earth Element (LREE) potential and specific uses. The soil with characteristic low plasticity has Liquid Limit (LL) brine value 50%, was more ideal for the primary forest

Pengaruh Supervisi Dan Peran Kepala Sekolah Terhadap Kinerja Mengajar Guru SD Negeri Di Kecamatan Rumbai Pesisir

Penelitian ini bertujuan untuk mengetahui pengaruh supervisi dan peran kepala sekolah terhadap kinerja mengajar guru SD Negeri di kecamatan Rumbai Pesisir Data dalam penelitian ini diperoleh dari kuesioner yang bersumber dari guru. Data dianalisis menggunakan regresi berganda. Hasil penelitian menunjukkan bahwa: 1) Terdapat pengaruh yang signifikan antara supervisi dan Peran kepala sekolah terhadap kinerja mengajar guru SD Negeri di kecamatan Rumbai Pesisir, dimana Fhitung (61,101) > Ftabel (1,654). Berdasarkan koofisien determinasi (R Square) = 0.441 atau 44,1%. Besar pengaruh supervisi dan peran kepala sekolah terhadap kinerja mengajar guru SD Negeri di kecamatan Rumbai Pesisir sebesar 44,1% berada pada tingkat sedang. 2) Terdapat pengaruh yang signifikan antara peran supervisi terhadap kinerja mengajar guru SD Negeri di kecamatan Rumbai Pesisir, dimana Fhitung (6,173) > Ftabel (1,654). Berdasarkan koofisien determinasi (R Square) = 0.440 atau 44%. Besar pengaruh supervisi dan peran kepala sekolah terhadap kinerja mengajar guru SD Negeri di kecamatan Rumbai Pesisir sebesar 44% berada pada tingkat sedang. 3) Terdapat pengaruh yang signifikan antara peran kepala sekolah terhadap kinerja mengajar guru SD Negeri di Kecamatan Rumbai Pesisir, dimana Fhitung (5,417) > Ftabel (1,654). Berdasarkan koofisien determinasi (R Square) = 0.403 atau 40,3%. Besar pengaruh supervisi dan peran kepala sekolah terhadap kinerja mengajar guru SD Negeri di kecamatan Rumbai Pesisir sebesar 40,3% berada pada tingkat sedang. Kesimpulan dari penelitian ini bahwa supervisi dan peran kepala sekolah berpengaruh positif dan signifikan terhadap kinerja mengajar guru SD Negeri di kecamatan Rumbai Pesisir

KARAKTERISTIK MINERAL LEMPUNG PADA JALAN RAWAN LONGSOR JALUR LIWA-BUKIT KEMUNING BERDASARKAN ANALISIS SEM DAN XRD

Tanah residu vulkanik jalur transek Liwa-Bukit Kemuning, Lampung Barat dijadikan objek penelitian dengan tujuan untuk mengetahui karakteristik mineral lempung yang terkandung. Analisis SEM dan XRD dilakukan terhadap lima sampel tanah permukaan. Berdasarkan kedua analisis tersebut mineral lempung yang hadir adalah kaolinite, illite, dan halloysite. Kaolinite memiliki karakteristik triklin, melembar dan berlapis. Illite memiliki karakteristik lembaran-lembaran menekuk dan menyerat. Sedangkan halloysite hanya hadir di analisis XRD

SUSCEPTIBILITY ASSESSMENT OF EARTHQUAKE-INDUCED LANDSLIDES: THE 2018 PALU, SULAWESI MW 7.5 EARTHQUAKE, INDONESIA

A catastrophic Palu earthquake on September 28th, 2018 with Mw 7.5 triggered countless slope failures, generating numerous landslides. This paper presents a practical method for susceptibility assessment of earthquake-induced landslides in the Palu region and the surrounding area. The statistical weight of evidence (WoE) model was used to assess the relationship between landslides induced by seismic motion and its causative factors to determine the susceptibility level and derive an earthquake-induced landslide susceptibility map of this study area. The 1273 landslides were classified into two data series, training data for modelling (70%) and test data for validation (30%). The six selected thematic maps as landslide causative factors are lithology, land use, peak ground acceleration (PGA), and slope (gradient, aspect, elevation). The selection of causative factors considerably influences the frequency of landslides in the area. The result is satisfactory because the AUC value of the chosen model excelled the minimum limit, which is 0.6 (60%). The estimated success rate of the model is 85.7%, which shows that the relevancy of the model is good with the occurrence of landslides. The prediction rate of 84.6% indicates that the applied model is very good at predicting new landslides

Swelling potential of volcanic residual soils in Sumatra (Indonesia) in relation to environmental issues

Swelling potential characterization of clay-silt soil is an essential issue in stabilization, settlement, consolidation, and land suitability studies. This article attempts to explain the swelling characteristics of soils around the area of West Lampung, Lampung Province, Sumatra, Indonesia, in relation to environmental issues. An investigation in relation to the soil swelling potential was carried out using 15 disturbed soil samples collectd in the study area. The methods used were analyses of clay mineral geochemistry, physical characteristics, and the free swell ratio. These results showed that the soil in the study area was Quaternary tropical volcanic residual soil. These soils were formed in a proximal volcanic hydrothermal alteration environment. The soils of the study area have characteristics of high plasticity, a reddish-brown colour, and are clayey silt grained (MH) (USCS). The soils had loose physical characteristics in dry conditions; however, these soils tends to be plastic and sticky in wet conditions. Evidence of groove erosion was found at the soil surface. Based on XRD analysis, kaolinite, halloysite, and montmorillonite were types of clay minerals found in the soil. The soil had a clay content of 11.05–78.9%, a liquid limit value > 50%, a plasticity index value of 16.7–36.9%, a shrinkage value of 14.24–36.89%, a soil activity of 0.38–2.47; and an FSR value of 0.69–0.95. These characteristics have implications for swelling soil potential. The results showed that the soils in the study area had medium to very high swelling potential. These results suggest a risk of erosion in the area, which could cause soil degradation and a change in water quality. These soils are likely to affect land productivity and aquifer replenishment and will cause negative environmental and economic impacts. Thus, soil improvement techniques are needed. It is important to maintaining vegetative cover these soils and revegetation may be required