Identification of Soil, Rock and Tecto-Volcanism on Landslides in Tondano Watershed

Abstract

This research was aimed to identify the soil, rock, and tecto-volcanism in their association with landslides intensity in Tondano watershed. The methods were survey method (soil, rock, and geomorphology), joint data processing with stereonet 8, X-ray diffractometers for clay mineral identification, and earthquake data processing with GIS 10.2 Software. The magnitude of earthquake was 4-5.4 mb that resulted from tecto-volcanism activity. The earthquake caused the instability of soil and rock, especially in fault zones. The rock has been strong deformed with the highly developed intensity of fractures (advanced stage). Soil dominated by Kaolinite and vermiculite minerals causes the instability conditions when it is saturated, while the nature of the bedrock with massive open fracture pattern causes the shear strength of the rocks decreases and on the contrary, the shear stress increases. Rainfall intensity is 73-145 mm/day that becomes a major factor of increased soil mass and burdening factor of the unstable rock. Slope is a factor that supports the intensity of mass movements of rock and soil in the form of shallow landslides.

Landslide-prone areas in Makale Selatan with the analytical hierarchy process method

“…A landslide will occur if the gravitational component is so large that the resistance to soil friction in the sliding plane is exceeded [13]. Thus the steeper the slope, the greater the chance of landslides occurring [14,15]. Makale Selatan is dominated by areas that are slightly prone to landslides.…”