Rainfall-induced landslides in Singapore

Minor, shallow landslides have occurred frequently on the island of Singapo re. However, very few major landslides (greater than 10 m in height) have o ccurred. Slope failures in the sedimentary Jurong and granitic Bukit Timah formations have occurred largely on slopes with angles greater than or equa l to 27 degrees. It is clear that rainfall has been the dominant triggering event for landslides in Singapore. Observations of past landslide events s uggest that a total rainfall of 100 mm within a six-day period is sufficien t for minor landslides to take place. The equivalent condition for major la ndslides would appear to be 320 mm within 16 days but this is based on very limited data.