Identitifikasi Struktur Permukaan Bawah Tanah di Situs Calok Kabupaten Jember Menggunakan Metode Geolistrik Resistivitas Konfigurasi Wenner-Schlumberger

Abstract

Jember Regency is one of the regions that has many ancient relics from the megalithic era, such as Deres Temple in Gumukmas District, Seputih Sarkofagus Site in Mayang District, Beteng Site in Semboro District, Suko Site in Jelbuk District, and Duplang Site, Klenceng Site, and Calok Site located in Arjasa District. The Calok Site is located in Calok Hamlet, Arjasa Village, Arjasa District. There is a block of andesite rock in the form of a dolmen with half of its surface below ground level. These rocks are classified as megalithic rocks located not far from the Calok Site. The purpose of this study was to identify the subsurface structure at the Calok Site, Jember, using the Wenner-Schlumberger configuration resistivity geophysical method. The study was conducted on five lines, each 30 meters long with a spacing of 1.5 meters. The data acquired in the field was analyzed using 2D inversion with Res2Dinv software and modeled in 3D using Voxler software. The two-dimensional inversion process using Res2Dinv software yielded overall resistivity values for the traverse ranging from 0.982 Ωm to 472 Ωm. The formation of the subsurface structure at the Calok Site consists of several types of rock, such as clay, sandy clay, volcanic tuff, volcanic breccia, and andesite. Clay and sandy clay are the most dominant layers with blue and green colors and have a resistivity range of 0.982 Ωm to 88.8 Ωm. There is an andesite rock anomaly with a resistivity range of 157 Ωm to >472 Ωm. In addition, there are volcanic breccia and volcanic tuff rocks with resistivity values ranging from 49.9 Ωm to 88.5 Ωm and 147 Ωm to 263 Ωm, which represent the argopuro breccia rock formation as depicted on the Jember Regency geological map