‘Main cause is man-made’

PETALING JAYA: Malaysia’s rugged topography and high rainfall coupled with human activities are behind the country being among the top 10 countries with the most number of landslides.

Institute of Geology spokesman Ng Chak Soon said Nasa’s data was correct.

“This is due to a combination of natural factors and human activities. Natural factors comprise periods of high rainfall and rugged topography while human activities relate to the cutting of slopes,” he said in an interview.

Asked if the high frequency could also be due to the type of soil in Malaysia, Ng said this was true only for Sabah such as in Ranau.

“Sabahan soil seems to have a high percentage of expandable clay which absorbs more water and expands more when wet. It shrinks when dry,” he said, adding that earthquakes were also a new factor in the state.

Not a country with typhoon or volcanic eruptions, Ng said the country’s only threat came from landslides.

“And, this is mostly man-made.

“Practically every major landslide in this country is linked to engineering works where slopes have been cut or built or filled with material,” he said.

To a question whether Malaysia had to change its type of development work such as slope cutting to reduce landslides, Ng said: “Apart from the coastal plains, most of our country is hilly.

“That means slope cutting is inevitable.”

He said there was a lack of in-depth understanding of the underlying factors behind landslides among “experts” in the country.

Whenever a slope failed as part of engineering works, he said it was engineers who looked into the causes of failures or what could have been overlooked, overestimated or underestimated in their calculations.

“It is unfortunate that most of these reports (into landslides) are not freely available for public scrutiny,” said Ng, adding that this made it difficult to identify the causes and to prevent similar mistakes from recurring.

He also claimed there was a lack of appropriate geological input in the study into the causes of landslides.

In many countries landslides come under the ambit of their geological survey departments.

“Malaysia is the exception where the Geoscience and Minerals Department is not playing this key role and there is a very good reason for this,” said Ng.

“Landslide as a geological phenomenon is a topic under engineering geology which is itself a branch of geology.

“Landslides began to be considered a problem only after the collapse of the Highland Towers in 1993.

“So, it is relatively new in Malaysia.

“To really have a better understanding of why slopes fail, we have to get the geologists involved,” he said.