Weathering Controlled Landslide in Deccan Traps: Insight from Mahabaleshwar, Maharashtra

Abstract

Landslide is one of the devastating natural phenomenon that threatens human life and property. Every year a number of persons lost their lives due to the landslides. Therefore, a better under-standing and characterization of landslide is very essential for adopting mitigation strategies to contain the adversities of this natural hazard. Information on landslides from different climatic setup are very essential for better understanding of the influence of weathering, rainfall, or topography on landslide generation. Weathering is one of the important causative factor for landslide generation in the moderate topography or inactive mountainous terrain. The Western Ghats including the Deccan Traps, an inactive mountain range, receives torrential rainfall. Intense rainfall in these areas enhances the weathering processes and fabricates thick soil covers. Mahabaleshwar area, Maharashtra was chosen as a case study, where high elevated part is covered by lateritic layer and each lava flow unit is separated by a thin weathered bed of red bole. The area experiences series of landslides during the summer monsoon months. Mainly two types of landslides have been identified in the area confined with the red bole bed and powdery lateritic soil. The first type of landslides occur at higher elevations (≥1200m) where horizontal beds of permeable laterites underlined by impermeable thick basalt beds. The rain water infiltrates down and spread laterally within the permeable lateritic beds. It finally spouts at lower plateau elevations and triggers mainly debris flows. The other category of landslides occurs where the weathered red bole bed separates two successive lava flows. The percolating water from the secondary porosities (joints and inter connected vugs) comes out from the contact zones of basalt and red bole bed in the form of seepages. It erodes the red bole bed and as a result the overlying masses hang and consequently lead to rock fall. The Chemical Index of Alteration (CIA) of the representative samples from landslide locations indicates significant weathering. The CIA values for the fine lateritic soil are up to 98% whereas for the red bole bed it varies from 77 to 85%. This suggests a high chemical weathering and higher erodibility. The association of active landslide locations with the red bole bed and fine lateritic soil suggests a close relation between weathering and landslide occurrences in the area.

Co‐seismic landslides in the Sikkim Himalaya during the 2011 Sikkim Earthquake: Lesson learned from the past and inference for the future

“…In the mountainous region, toe cutting of a slope by stream or river makes it unstable and vulnerable to landslide (Joshi et al, 2018). In tectonically active region, rivers incise its valley fast (Thakur et al, 2014).…”

“…In tectonically active region, rivers incise its valley fast (Thakur et al, 2014). Any change and/or modification of toe part of slope influences the stability of a slope (Joshi et al, 2018). Removal of toe part increases gravity‐induced shear stress and makes it susceptible to failure (Claessens et al, 2013).…”

“…Lithology plays a significant role in landslide generation (Joshi et al, 2018(Joshi et al, , 2021. In the weak lithology, clayey layers allow downward water movement and serve as the gliding plane for the overlying masses (Joshi et al, 2021).…”

Debris Flow Classification and Risk Assessment Based on Combination Weighting Method and Cluster Analysis: A Case Study of Debris Flow Clusters in Longmenshan Town, Pengzhou, China

“…Due to the characteristics of high density, strong fluidity, and fast flow velocity, debris flows are highly destructive. In recent years, frequent debris flows have significantly harmed human life, property, the economy, and the environment, especially in mountainous areas' seismic and geological active zones [4][5][6]. The CMLR (Chinese Ministry of Land and Resources) reports that thousands of disasters occur yearly in China, and mountainous hazards threaten 74 million people.…”

Stability evaluation of hazardous translational slide zones in part of Yamunotri Pilgrimage route, National Highway 507, Uttarakhand, India

“…Additionally, the extensively active methods for stability investigations in used are: i) empirical approach as rock mass rating (Taherniya et al, 2014;Abbas et al, 2015;Romana et al, 2015;Mondal et al, 2016;Regmi et al, 2016), ii) neural network (Ermini et al, 2005); statistical (Carrara et al, 1991;Chung et al, 1995;Jade et al, 1993;Li & Xu, 2016), iii) GIS based (Chand, 2011;Singh et al, 2020) and iv) analysis using charts (Hoek et al, 1981;Shen et al, 2013;Eid, 2014). Slope instability depends upon a number of parameters associated with slope, discontinuity, lithology, meteorology, weathering and others (Hoek and Bray, 1981;Harp et al 1990;Reeuwijk 1993;Wieczorek 1996;Iverson 2000;Pradhan et al, 2011Pradhan et al, & 2014Ahmad et al, 2013;Springman et al, 2013;Joshi & Rajan, 2018).…”