by David Toll, School of Engineering, Durham University, currently academic visitor at the National University of Singapore. This paper was first published in GE’s April 2006 issue.
Landslides are often triggered by rainfall, particularly in South-east Asia, where rain storms can be very intense. Major events, such as the recent tragic mudslide on 17 February in Leyte in the eastern Philippines, occur all too frequently.
However, minor landslides are even more common. Although they may not lead to loss of life, they still have economic and social impacts. Figure 1 shows a slide that happened on the campus of the National University of Singapore (NUS) on 11 January this year. With typical Singaporean efficiency, remediation was carried out very quickly, but it still caused safety concerns and incurred repair costs.
Such minor, shallow landslides have occurred frequently on the island of Singapore, particularly as urban development has greatly increased since the 1970s (Tan et al, 1987). However, there have been very few major landslides; where slides have happened, the volumes of material involved have generally not been large and serious damage has been rare (Brand, 1984; Toll et al, 1999).