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Journal : Journal of Physics and Its Applications

Depicting the Underground River Systems in Karst Mountains of Buayan and Ayah Subdistricts Using GGMPlus Data and Springs Distribution Agung Wibawa; Siti Fauzatun
Journal of Physics and Its Applications Vol 5, No 1 (2022): November 2022
Publisher : Diponegoro University Semarang Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/jpa.v5i1.13210

Abstract

The karst mountain area in Buayan and Ayah subdistricts is a mountainous area that stretches from North to South and ends in the South coast region. In this area, many springs are found which are a source of clean water for residents. The existence of springs in the area is an indicator of the existence of underground rivers flowing under the mountainous area, this is also reinforced by the presence of interconnected caves and the existence of river flows in these caves. Analysis the presence of underground river flows in the Karst mountain area in the study area can be identified by looking at the type of rock formations that dominate the area. The density contrast shown through the residual gravity data also shows changes in rock formations related to the presence of water sources in the study area. GGMPlus data was obtained from forward modeling in order to get a residual map. This study shows that rock formations in the Karst area in the study area conform to the topographical shape.
Pangandaran Earthquake and b-value Analysis for Better Understanding of Seismic Vulnerability in Java using Statistical Earthquake Data of 2002-2010 Wachidah, Siti Fauzatun; Wibawa, Agung; Ardhiansyah, Kurniawan; Syauqi, Muhammad
Journal of Physics and Its Applications Vol 7, No 4 (2025): November 2025
Publisher : Diponegoro University Semarang Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/baf.%v.%i.%Y.%p

Abstract

The application of statistical methods in seismicity analysis can provide a robust description of the relationship between earthquake magnitude and frequency in each region. This statistical relationship is formulated using the Gutenberg-Richter law, which continues to be developed through empirical and analytical studies of earthquakes in many regions. This study aims to analyze two significant earthquakes that affected the island of Java in 2006: the destructive Yogyakarta earthquake on 27 May 2006 and the Pangandaran earthquake on 17 July 2006. Both events were generated by active subduction mechanisms on the southern side of the island, where earthquakes of various magnitudes occur periodically. Through a temporal and spatial analysis of the b-value, this study compares different earthquake catalogs and analyzes the seismic vulnerability of Java by calculating the deformation caused by the 2006 earthquakes. The calculated b-values from the USGS and IRISDMC earthquake catalogs are 1.38 ± 0.04 and 0.92 ± 0.01, respectively. The magnitude of completeness (Mc) values are 4.9 for the USGS catalog and 4.3 for the IRISDMC catalog. The earthquake data span from 2002 to 2010. Deformation calculations using the IRISDMC data for 2006 show that the Pangandaran earthquake resulted in a surface rupture length of 140.60 km, a rupture area of 3,235.94 km², and a displacement of 7.96 m.