Abstract

Author:
Sehah, Abdullah Nur Aziz, Lusia Silfia Pulo Boli, Hasbi Shahreza Alqubaysi

Doi: 10.26480/gsrj.01.2024.51.56

This is an open access article distributed under the Creative Commons Attribution License CC BY 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited

Resistivity data acquisition using the Vertical Electrical Sounding (VES) technique has been carried out in Padamara District, Purbalingga Regency, Indonesia. The research purpose was to obtain data on the depth and thickness of lava deposit formations which are estimated to function as fractured aquifers. The data acquisition results in the field were subsurface rock resistivity data spread at five sounding points with values ranging from 0.69 – 260.41 Ωm. The sounding points were located at the geographic position of 7°22′41.77″ and 109°17′54.03″ to 7°22′41.77″ and 109°20′35.47″. The resistivity data interpretation results were lithological logs at each sounding point, while correlation result between lithological logs was a hydrostratigraphic cross-section model. Based on this model, the stratigraphy of the research area was composed of top soil (0.69 – 61.23 Ωm); interbedded clay, silt, and sand (13.05 – 49.14 Ωm), laharic deposits of Slamet Volcano (114.69 – 260.41 Ωm), lava deposits with many cracks, fractures, and small cavities (64.31 – 94.55 Ωm), tuffaceous sandstone (25.59 – 39.14 Ωm), sand and tuff (8.37 – 20.32 Ωm). The aquifer conditions in the research area could be classified into three types, that are shallow aquifers in the Alluvium Formation, intermediate aquifers in the form of fractured aquifers in the Lava Formation, and deep aquifers in the Undak Formation. The results of the research show that the depth of andesitic lava deposits that function as fractured aquifers ranges from 3.31 – 136.90 m from the topographical surface, while the thickness ranges from 12.78 – 71.10 m.