Informatics Publishing Limited

G. S. Mehrotra ¹, S. Sarkar ¹, D. P. Kanungo ¹, K. Mahadevaiah ¹

Affiliations
1 Central Building Research Institute, Roorkee-247 667, IN

Abstract

Landslides and slope instability problems are quite common in Sikkim Himalaya. Recent developmental activities in this region have aggravated the incidence of landslides to a great extent. The ongoing developmental activities, therefore, call for delineation of safe and unsafe zones.

The present study involves the preparation of landslide hazard zonation map of East Sikkim Himalaya in a semiquantitative way by evaluating various terrain factors like lithology, structure, slope, landuse and drainage in relation to existing landslides. A numerical weightage called Landslide Susceptibility Value (LSV) has been assigned to each factor and Landslide Susceptibility Index (LSI) of each category of factor maps has been catculated. Based on the proposed methodology landslide hazard zonation map of the area is prepared showing five zones of slope instability. This map may serve as a base map for any developmental activities to be planned in the terrain. An attempt has also been made to establish the relationships of various geoenvironmental factors with the landslide activity with an objective to develop an appropriate methodology for landslide hazard zonation.

Keywords

Landslides Hazards, Terrain Analysis, Sikkim Himalaya.

Full Text

     

N. Harijan ¹, A. K. Sen ¹, S. Sarkar ², J. D. Das ³, D. P. Kanungo ²

Affiliations
1 Department of Earth Sciences, IIT Roorkee, Roorkee - 247 667, IN
2 Central Building Research Institute, Roorkee - 247 667, IN
3 Earthquake Engg., IIT Roorkee, Roorkee - 247 667, IN

Abstract

Sung Valley Carbonatite Complex (SVCC) of the Shillong Plateau is one of the important known carbonatite complexes in India. This complex has intruded the sub-vertical beds of Shillong Group rocks and occur along the major N-S trending pre-existing Um Ngot fault. Topographically, the carbonatite intrusion is marked by a prominent semi-circular depression formed due to weathering of soft nature of the rocks present in the complex. This characteristic is unique in relation to carbonatite and related rocks with the surrounding relatively hard lithological formations. This < feature is prominently displayed on satellite image. The drainage network of the study area is found to be strongly controlled by structure and lithology. The present study is an attempt towards morphotectonic interpretation of the SVCC and adjoining region using satellite imagery and spatial data integration in GIS environment.

Full Text