Matale ground subsidence and overlooked construction basics

Since few years back, there has been several cases reported on construction failures and sink holes in Matale due to a possible ground subsidence affecting human settlements in the region. Villagers have been living with a belief of an under ground river flowing in some areas of Matale. National Building Research Organization (NBRO) has been consulted in investigating the existing situation. Garnet silimanite biotite gneiss and Crystalline Limestone are found to be major rock types in the said area confirming a karstic geomorphology with caverns spreaded in a vast area. With the help of drilling and tube well records, and geophysical survey results, hazard zonation mapping has been initiated. The hazard zonation map shows nearly 2900 houses from 24 GN divisions found to be affected in a risk scale from high to very low. A human settlement survey was carried among 89 houses of severely affected houses to investigate the extent of the damages and also to summarise civil engineering technologies adopted in their house construction. It was found that the construction basics had been overlooked due to lack of awareness among the residents in the said vulnerable condition prevailing in the area. This paper summarises basic geology of the area, mapping procedure and neglected construction basics which are vital factors that should be considered when human settlements found in problematic geological areas