Identification of Subsurface Lithology in Sendang Mulyo, Purwoharjo Village, Samigaluh Subdistrict, Kulon Progo Regency

Abstract

Research aimed to determining the lithological conditions subsurface of landslide areas in Sendang Mulyo, Purwoharjo Village, Samigaluh Subdistrict, Kulon Progo Regency by geoelectric and microseismic methods. The research had been conducted after knowing the subsurface lithology conditions, it could anticipate landslides as disaster mitigation. The location of research is on a hillside in Purwoharjo Village. The research located on that area because the history landslides. The area is the longest landslide and had a major impact on the villagers that located below the hill. The research used a set of resistivity geoelectric devices with Syscal brands and microseismic devices Digital Portable Seismograph brands TDL-3035 type Taide brands. In geoelectric method used 5 lines, 2 lines 150 m from north to south, 2 lines 120 m and 1 line 100 m from east to west, while the microseismic method used 30 points with spaces of 10-100 meters. The results of the geoelectric method are obtained lithology of clay material with resistivity of 0.16 - 160 Ω.m, sand material with resistivity 160 - 1093 Ω.m, sandstone material with resistivity 1093 - 8000 Ω.m, and a andesite material with resistivity of 8000 - 122165 Ω.m, while the results of the microseismic method obtained clay rock material having a value of Vs between 406.33 m/s and 742.52 m/s represented by the dark blue spectrum. In the middle landslide has a depth of clay material up to 33 meters. The results showed that subsurface lithology in the area is prone to landslides, because it is suspected that there is a sliding field at a depth of 33 meters. This is supported by the presence of andesite rocks which spread at a depth of 20 meters and above the andesite material, there is clay material that quite thick.

Lithological modelling based on shear wave velocity using horizontal to vertical spectral ratio (HVSR) inversion of ellipticity curve method to mitigate landslide hazards at the main road Of Samigaluh District, Kulon Progo Regency, Yogyakarta

“…Parameters in the form of P wave velocity (Vp), S wave velocity (Vs), and density are used as limits to obtain a model that approximates the actual subsurface structure. The parameters in this study refer to previous studies [8,[17][18][19]. Based on previous research, researchers made parameters in the research area which can be seen in Table 1.…”

“…Research conducted by [6][7] shows the dominant frequency and amplification values in Samigaluh District. While research [8] shows the value of shear wave velocity and lithology located in Samigaluh District.…”

“…To mitigate the landslide hazard, we mapped the soil vulnerability and lithology based on shear wave velocity (Vs) and layer thickness derived by microtremor datasets. Microtremor in soil structure studies is used to determine subsurface conditions [8][9]. This method was chosen because the equipment used is relatively simple, low cost, does not require a lot of energy [10] and low cost [11].…”

Dynamic rainfall thresholds for landslide early warning in Progo Catchment, Java, Indonesia

“…Other geological types mainly consist of alluvium, colluvium, and local igneous rocks. In situ studies using geophysical methods revealed the existence of sliding planes in several sites within the Catchment (Katriani et al 2019;Pratiwi et al 2019;Widyadarsana and Hartantyo 2021;Dzakiya et al 2023).…”