Geologist Warns Saturated Soils Behind Sabah S Deadly Landslides

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The deadly landslides that claimed 13 lives in Sabah were caused by waterlogged and unstable hill slopes following days of relentless rain, according to geologist Professor Felix Tongkul.
Tongkul, an expert on landslides and slope movements, said the continuous downpours had left the soil “super saturated”, reducing its strength and increasing its weight.
These conditions, he explained, make even gentle slopes vulnerable to collapse.
“The main cause of these landslides and debris flows is the continuous, intense rain over the past few days.
“With only short breaks of sunshine, the ground has become saturated with water. This reduces the strength of the soil and adds weight, making slopes far more prone to movement,” he explained.
At least 13 people have died in landslides and mudslides across Sabah over the past week. The victims include a 97-year-old man in Kampung Sarapung, Penampang, who was killed when his house collapsed under mud and debris last week.
Fatal deluge
Yesterday, the worst loss of life occurred in Kampung Cenderakasih near Kota Kinabalu, where seven people, including four children, were confirmed dead.
The houses there lie in disarray, built on privately owned land without approval and widely regarded as part of a squatter settlement.
In Kampung Maragang Tuntul, Papar, three members of a family - a 10-year-old girl, her 34-year-old mother, and her six-year-old brother - died after their home was buried.
Another two victims, a 38-year-old woman and her 11-year-old son, were also killed in Kampung Mook, Papar, when landslides swept away several houses.
ADSDanger in exposed hillsides
When soil on exposed hillsides becomes oversaturated with rainwater, it effectively softens and loses the strength needed to hold together, making it far more likely to slide downhill, Tongkul said.
The heaviest rainfall, he noted, was concentrated on the west coast, particularly in the lower Moyog valley near Penampang and Kota Kinabalu.
Tongkul also urged residents living near slopes to stay alert for warning signs of ground movement, such as cracks in the earth or trees beginning to tilt.
“If you notice these, move quickly to safer ground,” he said, adding that once soil becomes oversaturated, even a slope as shallow as five degrees can begin to shift, producing debris flows.
Firefighters recovering a body from a house buried by landslide in Sabah“Of course, the steeper the slope, the higher the risk,” Tongkul added.
Tongkul is a geologist from Sabah, Malaysia, well known for his work at Universiti Malaysia Sabah (UMS). He served as director of the Natural Disaster Research Centre at UMS before retiring in 2021.
His academic expertise covers sedimentology, stratigraphy, geological mapping and the study of geohazards, including landslides and debris flows, across Sabah and northern Borneo. - Mkini

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