Identifying Probable Slip Surface in Wanurejo, Borobudur District, By Subsurface Analysis Utilizing the Dipole-Dipole Configuration of Resistivity Method

Research has been carried out on the existence of slip surfaces in Wanurejo, Borobudur District, Magelang Regency, Central Java. The location of the slip surface is identified using the resistivity method of the dipole-dipole configuration. This research was conducted at a relatively flat measurement location and at an altitude of around 95–105 meters above sea level. Measurements were made on 6 different lines with a length of track 1 of 250 m. The results of data processing indicate that the layer that acts as a slip surface is a layer of clay. The clay layer has a resistivity value ranging from 15 to 35 ohm.m, which is relatively thin, so it has the potential to become a slip surface because it is located between two rocks that have a significant resistivity contrast: compact andesite rock and water-saturated sandstone. If the water-saturated sandstone layer is no longer able to withstand the weight above it, the surrounding andesite rocks will easily slip. This is also reinforced by the presence of a layer of clay that is slippery, so the potential for landslides or slipping is greater. &nbsp

Study of Groundwater Types Using the Vertical Electrical Sounding (VES) Method in the ‘Martani Field’ Ngemplak District of Yogyakarta

Study of groundwater types using the Vertical Electrical Sounding (VES) method in 'Martani Field’ Ngemplak District of Yogyakarta was done by carrying out eight measurement points to look for groundwater potential. This area is an area on the southern slopes of Mount Merapi which is included in the Yogyakarta Groundwater Basin. The type of lithology is identified based on the measurement of its resistivity value so that there are several types of lithology, namely Breccia (110-670 Ωm), Clay (1.99-10.12 Ωm), Sandstones (17.06-56.82 Ωm) and andesite lava (688-1657 Ωm). The bottom of the aquifer in this basin is composed of rock formations that are impermeable or semi impermeable which are non-aquifer, namely by Breccias, Clay and Andesite Lava. The existence of sandstones that act as aquifers is found near the surface at a depth of <25 m and at a depth of about 60-100 m below the surface so that it is divided into two categories, namely shallow groundwater and deep groundwater