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WITHDRAWN Identification of Rock Structures in the Southern Coast of Yogyakarta Based on Geophysical Exploration Analysis of the Karangwuni Beach Segment, Kulon Progo, Using the Wenner-Schlumberger Array Method

Description: 

WITHDRAWN The southern coast of Yogyakarta is located the tectonic subduction zone between the Indo-Australian Plate and the Eurasian Plate. This setting induces geological activity, such as the formation of fault structures, fractures, and sediment layer changes. This results in the creation of complex geological structures on the island of Java, including folds, faults, and volcanic activity (Harjanto, 2011). Coastal geological characteristics, such as seawater intrusion, erosion, and sedimentation, have the potential to affect the stability of the region and the livelihood of coastal communities. The geoelectric method is used to observe the changes in resistivity of rock layers both vertically and horizontally. The Wenner-Schlumberger Array method was chosen for its ability to provide detailed subsurface resistivity information both laterally and vertically. Apparent resistivity is calculated using field data that has been calibrated with geometric factors, and the results reflect the initial distribution of subsurface conductivity (Telford et al., 1990). Data interpretation is performed based on cross-sectional results obtained from the inversion process to identify characteristics of subsurface materials (Loke, 2003; Zohdy et al., 1974). The interpretation of geoelectric data identified the presence of aquifer lenses, which are characteristic of aquifer systems in coastal areas. These aquifers generally contain brackish water with high salinity (1.15–4.00 Ωm), indicating significant seawater intrusion. The distribution of these aquifer lenses is uneven, with six locations showing freshwater (13.9–48.1 Ωm) at depths between 5 and 25 m, reflecting the dynamic hydrogeological system of the coastal area. Additionally, the interpretation revealed the presence of bedrock in the form of sandstone (167–2005 Ωm) located at depths ranging from 30 to 86.2 meters below the surface.The estimated potential for freshwater in this area is approximately 11,388,559 m³. This presents a high potential risk for coastal subsidence or landslides, which could be triggered by significant earthquakes from the Southern Java megathrust.

Session: Earthquake Shaking and the Geologic Record: Triggered Phenomena and Preserved Fragile Geologic Features [Poster]

Type: Poster

Date: 4/17/2025

Presentation Time: 08:00 AM (local time)

Presenting Author: Setyoajie

Student Presenter: Yes

Invited Presentation: 

Poster Number: 27

Authors