Geomorphological investigation of the excavation-induced Dundar landslide, Bursa, Turkey

Abstract

This paper discusses the occurrence and development of the excavation-induce deep-seated landslide, which took place near Dundar village, located west of Orhaneli town in northwestern Turkey. The event occurred in the Bursa-Orhaneli lignite field, which has been actively operating since 1979. Due to undermining of a gently inclined slope (10 degrees) to extract a coal seam, primary tension cracks, which were precursors of the movement, were first observed in the northern head area in mid- to late October 2003. This movement happened simultaneously with precipitation that was significantly above long-term average measured at a nearby climatology station (Keles). This precipitation amount is characterized statistically by a significant standardized anomaly of 1.6. The majority of the monthly precipitation total in October 2003, which mainly consisted of rain showers and thunderstorms, occurred in the last week of the month. By April 2004, rotational failure continued intermittently. After a relatively wet (rainy and snowy) period from January 2004 to April 2004, the main rotational slump occurred in late April 2004, causing the entire destruction of Dundar village's cemetery. Daily climatic and synoptic meteorological data have proved that heavy showers in late April may had triggered the last slump by producing rain showers of 19.3 mm and 19.9 mm daily total on 27 and 28 April 2004, respectively.