Journal of Science and Applicative Technology

Effect of Azimuthal Variability in Estimation of HVSR Parameters and Ground Shear Strain at Kota Baru, South Lampung, Indonesia

Vico Luthfi Ipmawan — 2025-04-19

Kota Baru, a potential capital of Lampung Province in South Lampung, Indonesia, faces significant earthquake risks due to the Great Sumatran Fault and the Sumatra Megathrust. Geologically, the area is part of the Plio-Pleistocene Lampung Formation, predominantly composed of rhyolite-dacite tuff and volcanoclastic tuff, which can amplify seismic shaking. This study investigates azimuthal variations in the Horizontal-to-Vertical Spectral Ratio (HVSR) across 15 locations in Kota Baru to identify their underlying causes. The results show notable changes in peak amplitude (Ao) and dominant frequency (fo) across different azimuths, with Mean Absolute Deviations (MAD) ranging from 0.96 to 5.71 for Ao and from 0.00 to 1.57 for fo. Maximum HVSR values were predominantly observed at azimuths below 30° across most regions. These variations are likely related to differences in soft layer thickness and/or the presence of a suspected fault near the study area, both of which could influence seismic wave propagation. A model of an 8.9-magnitude megathrust earthquake revealed no significant differences in Ground Shear Strain values, with results remaining within the same Modified Mercalli Intensity (MMI) scale. Therefore, despite azimuthal variability, the assumption of isotropic ambient noise in Kota Baru remains valid.

Statistical Pattern Recognition of Lithosphere Anomalous Activity Along the Indonesian Ring of Fire

Mika Alvionita S — 2025-04-19

The introduction of statistical pattern recognition becomes highly important for assessing disaster threats such as earthquakes. This approach is significantly more comprehensive and suitable for long-term event forecasting. Therefore, in the future, efforts can be promptly made to reduce the risk of disasters resulting from anomalies in lithospheric activity, especially frequent earthquakes in the Sumatra Island region, Indonesia. Statistical pattern analysis of lithospheric activity anomalies can be categorized through classification. Earthquake classification is performed based on magnitude scale and mathematical calculations of earthquake parameter unit conversion. The classification method employed in this research includes machine learning methods like k-nearest neighbor and support vector machine. The evaluation metrics used for machine learning models are model accuracy and confusion matrix tables.

Quantitative Profiling of Total Flavonoid Content in Cassava Leaf (Manihot esculenta Crantz) Varieties and Isolation of Flavonoid Compounds from a High-Flavonoid Variety

Syaikhul Aziz — 2025-06-18

Cassava (Manihot esculenta Crantz) is widely utilized across Indonesia as both a staple food and a traditional medicinal resource, and its leaves are known to contain bioactive secondary metabolites such as flavonoids. This study aimed to quantify the total flavonoid content in several cassava leaf varieties and to isolate a flavonoid compound from the variety with the highest flavonoid content. Total flavonoid content was determined using UV-Visible spectrophotometry. The isolation of flavonoid compounds was carried out using vacuum liquid chromatography (VLC) and column chromatography (CC), with thin-layer chromatography (TLC) employed to monitor the separation results. The total flavonoid content of the Gajah, UJ-3 (Thailand), UJ-5 (Katsesart), Cimanggu dan Kaspro varieties were found to be 1.029 ± 0.003 mgQE/g, 0.746 ± 0.006 mgQE/g, 0.970 ± 0.009 mgQE/g, 0.936 ± 0.004 mgQE/g and 1.220 ± 0.003 mgQE/g, respectively. The Kaspro variety exhibited the highest flavonoid content. Isolation and characterization of the flavonoid from Kaspro leaves yielded a yellowish powder with absorption maxima at 269 nm (Band II) and 334 nm (Band I). Further analysis using shift reagents identified the isolated compound as apigenin, a member of the flavone group.

Calculation of The Chain Ladder and Bornhoutter-Ferguson Methods in Calculating Claim Reserves for Insurance of Property Company in Sumatra

Dila Tirta Julianty — 2025-08-03

Property insurance provides financial protection against the risk of loss due to damage or loss of insured property, such as buildings, vehicles, and equipment. Property insurance companies are required to maintain sufficient reserves to meet future claim obligations. Therefore, these companies need to accurately estimate claim reserves. This study aims to compare two methods of estimating property insurance claim reserves Chain Ladder method and Bornhuetter-Ferguson method. The data used in this research is secondary data obtained from property insurance in Sumatra, covering production and claims data from 2018 to 2023. The Chain Ladder method is a straightforward approach that uses historical claims development patterns to project future claims. The Bornhuetter-Ferguson method combines information from paid claims and estimates of the loss ratio from earned premium to predict reserves. Both methods are compared to assess their accuracy in estimating claim reserves using the Mean Absolute Percentage Error (MAPE). The results of this study indicate that the Bornhuetter-Ferguson method provides better estimates of claim reserves compared to the Chain Ladder method.

Mineralogical Characteristics and Critical Stress Variation in Rock Samples from Bukit Kunyit, Bandar Lampung

Muhamad Ragil Setiawan — 2025-08-03

Mineralogy is essential for understanding rock formation processes and their physical properties, including critical stress. Critical stress values can be estimated using unconfined compressive strength (UCS) measurements, which depend on the modulus values of the minerals present. This study explores the mineralogical characteristics of rock samples from Bukit Kunyit, Bandar Lampung City, and Lampung through X-ray diffraction (XRD) and petrographic analysis. Macroscopic observations revealed two visually distinct rock samples: one with a bright color (Sample 1) and another with a darker hue (Sample 2). Despite these color differences, XRD analysis showed that both samples have the same mineral composition, including Anorthoclase, Cristobalite, Tridymite, and Muscovite, indicating a felsic (silica-rich) nature. Differences were noted in the crystallographic forms of Muscovite and Quartz content, with Sample 2 having a higher Quartz concentration. These mineralogical variations correlate with the observed differences in critical stress, with Sample 1 exhibiting a lower critical stress (20.98 MPa) than Sample 2 (35.05 MPa).