Pengukuran resistivitas secara sounding telah dilakukan di daerah Candi Dasa (CD), Provinsi Bali. Tujuan penelitian ini adalah mengidentifikasi sumber air tanah baru. Untuk menentukan posisi aquifer air tanah bawah permukaan maka dilakukan pengambilan data sounding di dua titik yaitu CD 1 dan CD 2. Metode yang digunakan adalah metode geolistrik resistivitas Konfigurasi Schlumberger dengan panjang lintasan CD 1 dan CD 2   adalah 150 m dengan spasi 1 m.  Pemrosesan data dengan menggunakan software IP2Win dan Progress 3 untuk memungkinkan penggambaran distribusi resistivitas batuan dalam 1 D. Hasil interpretasi menunjukkan bahwa struktur batuan bawah permukaan terdiri dari batuan soil, tuff, lava dan sandy tufa. Hasil interpretasi menunjukkan bahwa lapisan batuan yang terdapat terbentuk karena aktifitas vulkanik yang berasal dari aktifitas Gunung Agung yang berada di Kabupaten Karang Asem. Batuan seperti lava dan tuff adalah batuan yang memiliki porositas yang kecil karena memiliki ukuran butiran yang halus dan kecil, memiliki permeabilitas yang rendah sehingga menyebabkan susah untuk menyimpan dan dan mengalirkan air. Lapisan batuan ini diperkirakan berfungsi sebagai lapisan impermeable dan selanjutnya berfungsi untuk menahan air yang mengalir secara horizontal. Selanjutnya, lapisan batuan sandy tufan yang memiliki porositas dan permeabilitas yang besar karena memiliki butiran batuan yang besar bertugas untuk menyimpan dan mengalirkan air.

ABSTRACT:Research on landslide in Sri Mulyo Village, Dampit Subdistrict, Malang District, Indonesia has been implemented. This research is conducted to know the condition of the subsurface area for information in landslide vulnerability analysis. In addition, this research was undertaken to mitigate landslide in minimizing casualties and material losses. The study was done using resistivity method, configuration of dipole-dipole supported by drilling core lab test result. There are five resistivity measuring lines with trajectory lengths ranging from 100 m, 200 meters, and 300 meters. The results of the resistivity indicate that the subsurface lithology of Sri Mulyo Village is composed of clays (9.3-85.8 Ω.m), tuff (178-779 Ω.m) and breccia (≥ 1629 Ω.m). The sliding plane at the research area is the boundary between clays and tuffs. The result of correlation between geoelectric and drilling core data showed that the research area was dominated by a 10m depth of clay. High rainfall, clay thickness and vegetation (coffee) exhibit high levels of vulnerability to occur landslides. Possible landslide direction is from West-West to Southeast with creep avalanche type.

was undertaken. This research was conducted to identify volcanic sediments layers' which contact with Limestone Sediments in the surrounding of Sutami Dam and to mitigate potential disasters in the dam's surrounding area. This research was conducted by a geomagnetic method. Data were collected using the Proton Precession Magnetometer G-856. The geomagnetic data acquisition started from the Kromengan District (112.494 o E; 8.129 o S) to the Sukorame District (112.358 o E; 8.213 o S). The radius of geomagnetic data acquisition was 15 km; the space between the points was 300 meters with 1372 measurement points. The value of the geomagnetic intensity are between -210 nT to 514 nT. The northern part of the research location has a lower total geomagnetic intensity than the southern area. The northern part is thought to be volcanic sediment (Tuff Desposits and Butak Volcanic Sediments), which only covers the surface, while the southern part is (Limestone Sediments) Marine sediment, which is some parts thought to have been volcanoes in ancient times. The ancient volcanoes in the southern part are Mounts Golo, Selorejo, Selumban, Tretes, Soko, Pehlembun and Krowedul. The contact layer between volcanic sediments with Limestone Sediments is more difficult to consolidate, so that the buildings built on them are more vulnerable.

Research has been carried out to determine the subsurface formations in the Sutami dam area and its surroundings using the magnetic method of pseudogravity transformation and satellite imagery gravity anomaly data. This study aims to compare the subsurface formations in the area around the Sutami Dam between the data of the pseodu-gravity transformation magnetic method and the gravity anomaly data of satellite imagery. Data acquisition using the pseudogravity magnetic transformation method was carried out using the Proton Precession Magnetometer (PPM) Scientrex Model G-8 with a spacing of 300 meters. Satellite imagery gravity anomaly data was taken from the Gravity Model Plus (GGM plus) with a spacing of 220 meters. The radius of geomagnetic data acquisition was 15 km. The number of data for the magnetic method of pseudogravity transformation was 1,372 measurement points and satellite imagery gravity anomaly data was 3,000 measurement points. The results showed that the rock formations from the magnetic method of pseudogravity transformation and satellite gravity anomaly data were compatible. There are 4 types of subsurface formations in the study area, namely soil (Δρ = 1.6 g/cm3), Butak Volcanic Product (Δρ = 2 g/cm3), Tuff Deposit (Δρ = 2.1 g/cm3) and Campurdarat Formation (Δρ = 2.6 g/cm3).

Research using geoelectric resistivity dipole-dipole configuration and slope stability analysis has been done in the area Jawar, District Dampit to find out the sliding plane landslide, landslide direction and factor of safety. Tracks Retrieval of data by the method of geoelectric resistivity as much as 5 tracks with the direction of the southeast to the northwest three tracks with a length of 100 m -200 m and southwest to northeast as many as two passes with a length of 200-300 m. While the slope stability analysis performed topographic map data retrieval and data collection sondir and boring. Based on the analysis of the lithology of the study area using resistivity geoelectric method shows three layers of soil is clay (the top layer), tuff (middle layer) and basalt and lava (bottom layer). Sliding plane landslide area is in the boundary between the layers of clay and tuff (a depth of 10.5 m). Based on the results of data processing of 3D resistivity geoelectric, landslide direction is southeast. Safety factor value of the security research area based slope stability analysis is 1.015. This value indicates that this area is prone to landslides.