Sunan Kalijaga Journal of Physics

Subsurface Structure Analysis for Determining the Slip Surface of Landslides Using the Wenner Resistivity Geoelectrical Method in Kokap, Kulon Progo

2025-10-25T05:59:56+07:00

Slope failures frequently occur in hilly regions, particularly during periods of intense rainfall. At the end of 2022, such an event affected a residential area in Hargomulyo Village, Kulon Progo. Mitigation efforts against similar hazards can be implemented through mapping of landslide-prone zones, one of which involves identifying the rock layers that act as the slip surface. This study employs the geoelectrical resistivity method with a Wenner configuration to characterize the subsurface structure based on variations in electrical resistivity of soil and rock. Data acquisition was conducted along four survey lines located within an andesitic intrusion formation composed of hypersthene–andesite to trachyandesite rocks. The modeling results indicate three main layers: surface soil with resistivity values below 54.4 Ωm, clay mixed with weathered andesite ranging from 54.4 Ωm to 141 Ωm, and intact andesite bedrock exceeding 141 Ωm. Correlation with the Geological Map of Yogyakarta Sheet (Rahardjo et al., 1995) confirms that the potential slip surface corresponds to the weathered andesite–clay zone developed along the contact between the Andesite Intrusion and the Kebobutak Formation. This transition layer, acting as a mechanically weak zone, controls slope stability in the study area. The presence of a local north–south fault may further increase groundwater infiltration and pore pressure above the impermeable andesite layer, promoting slope movement during heavy rainfall. These results emphasize that integrating resistivity interpretation with geological mapping provides a more comprehensive understanding of landslide mechanisms and supports hazard mitigation efforts in andesitic terrains of Kulon Progo.

Physiographic Study of Java Island Based on EMAG2 v3 Data

2025-10-25T06:05:45+07:00

This study aims to analyze the physiography of Java Island based on the Earth Magnetic Anomaly Grid version 3 (EMAG2 v3) satellite data. The EMAG2 v3 dataset represents a global magnetic anomaly compilation acquired from satellite measurements provided by the National Oceanic and Atmospheric Administration (NOAA). The magnetic method, a geophysical technique that utilizes variations in the Earth’s magnetic field anomalies, was employed to delineate subsurface geological structures. The datasets used include administrative maps, regional geological maps, physiographic maps, and magnetic anomaly maps derived from EMAG2 v3 processing. Data processing was performed using the Geosoft Oasis Montaj software to generate the magnetic anomaly map of Java Island. The results indicate that the magnetic anomaly values across Java Island range from −300 nT to 450 nT, showing spatial variations among different physiographic zones. The northern part of Java exhibits low to moderate magnetic anomalies that correlate with alluvial deposits and young sedimentary formations, while the southern part displays moderate to high anomalies, reflecting the presence of volcanic rocks and intrusive bodies. This analysis demonstrates a strong correlation between magnetic anomaly variations and the lithological as well as structural characteristics of each physiographic zone. Therefore, EMAG2 v3 data can be effectively utilized to comprehensively interpret the regional geological framework of Java Island.

Analysis of Rock Magnetic Susceptibility in a Local Fault Zone at Sangkrek, Kulon Progo Regency

2025-10-25T06:09:24+07:00

This study aims to analyze the pattern of magnetic anomaly distribution and determine the rock magnetic susceptibility values as a basis for identifying a local fault zone in the Dusun Sangkrek area, Kokap District, Kulon Progo Regency. The geomagnetic method was employed, with data acquisition conducted at 60 observation points using a Proton Precession Magnetometer (PPM) G-856 at 100-meter intervals. The total magnetic field data were corrected for daily variations and the International Geomagnetic Reference Field (IGRF) to obtain the total magnetic anomaly (ΔT). The magnetic anomaly values range from –3,1 × 10² nT to 6,8 × 10² nT, where high anomalies are dominant in the northern part, composed mainly of andesitic rocks, while low anomalies are found in the western and southern parts, corresponding to the Sentolo and Alluvium Formations. Data processing stages include reduction to the pole (RTP), upward continuation, and two-dimensional (2D) modeling to characterize subsurface magnetic variations. The modeling results indicate that the magnetic susceptibility of rocks varies between 1,0 × 10⁻⁴ and 1,1 × 10⁻¹ SI, with higher values associated with andesite and brecciated andesite, and lower values corresponding to siltstone, claystone, and sandstone. The contrasting distribution of susceptibility along several profiles reveals sharp lithological changes, interpreted as indications of a local fault zone that influences the subsurface magnetic distribution.

Modeling Of Tsunami Flood Maps Along The Malang Coast Using Commit 1.8.1 And Quantum Gis 2.18.28 “Las Palmas” Software

2025-10-25T06:15:21+07:00

The long coastline of Malang, located in the south of Java Island, is close to the Indian Ocean, which has a subduction zone. This makes Malang Regency a potential tsunami-prone area. Therefore, a tsunami inundation map is needed as a reference for creating a tsunami evacuation map. Tsunami inundation modeling is used to estimate the worst-case tsunami impact. The modeling was conducted using ComMIT (Community Model Interface for Tsunami) 1.8.1 based on an Mw 8.7 earthquake scenario taken from the 2017 Indonesian Earthquake Source and Hazard Center distribution of megathrusts and active faults in the South Java Sea, specifically in the East Java Megathrust zone. The inundation map was created using Quantum GIS 2.18. 28 Las Palmas The tsunami inundation modeling results showed that the inundation distance varied between 0.9 and 1.9 km inland, the tsunami height on the coast varied between 8.41 and 19.63 meters with a maximum run-up of 10 meters, and the tsunami arrival time on the coast was around 30 minutes after the earthquake occurred.

Preparation of Activated Carbon from Coffee Grounds as a Supercapacitor Electrode

2025-04-25T06:01:57+07:00

The growing demand for sustainable energy storage solutions has spurred interest in supercapacitors, with biomass-derived activated carbon emerging as a promising electrode material. This study investigates the fabrication and performance of activated carbon from spent coffee grounds for application in supercapacitors. Carbonization was carried out at 300°C, 500°C, and 700°C, followed by chemical activation using HCl, KOH, and ZnCl₂. The resulting activated carbons were characterized to determine their physicochemical properties. Optimal activated carbon was obtained at 700°C with KOH activation, yielding 84.75% fixed carbon and conforming to SNI 06-3730-1995 standards. Supercapacitor performance testing revealed that the best results were achieved using electrodes prepared from carbon obtained at 300°C and activated with ZnCl₂, yielding a voltage of 352.9 mV and a capacitance of 465.58 μF after a 1-minute charge. These findings suggest that spent coffee grounds are a viable source of electrode material for efficient, low-voltage supercapacitors.