Tuesday, May 24, 2011

News Straits Times 22 May 2011

'Vertically cut slope unstable'

KUALA LUMPUR: Initial investigations by geologists have revealed that the stricken slope in Saturday's incident had been cut vertically, severely weakening its foundation.

Universiti Kebangsaan Malaysia geologist Dr Tajul Anuar Jamaluddin said the hill had a 70 per cent vertical cut, making it highly unstable.

"The cutting of the hill was not done by professionals. There was no work done to stabilise the slope after it was cut.

"The hilltop also appears to have been cleared and this had caused rainwater to come rushing down the hill."

He said the clearing, believed to be for agriculture purposes, was about 130m long and 30m wide.

"Heavy machinery currently on the hill could have further destabilised the place," said Dr Tajul, who spent several hours on the hill yesterday.

He added that the area still remained dangerous and more landslides could occur.

Southeast Asia Disaster Prevention Research Institute director Datuk Dr Ibrahim Komo said such vertical cutting of the hillslope was typical of community development in village areas.

He said the area was known for landslides and based on information gathered so far, the slope near the orphanage was cut for several metres and the area around it had been flattened to build a house.

"This had weakened the hill's foundation and it was only a matter of time before a landslide occurred."

Unlike housing developments where hills are usually strengthened after cutting the slope, small-scale vertical cuttings are not strengthened and left to the mercy of the elements.

Dr Tajul said vertically cut hills usually failed in about two to three years, but some even lasted 20 years before they caved in.

The orphanage is believed to be about 10 years old.

Classified as a medium-scale landslide, he said heavy rains had only triggered the landslide and were not the main cause of the disaster.

"People should not blame the weather conditions. If rain was the cause, then many other hills in the area would have also experienced landslides."

He was also sure this was not the first such incident in the area, as smaller landslides or boulders may have come crashing down the hill before.

"Unless there was a loss of life, there would not have been much interest and people would not have reported them."

Dr Ibrahim said the hills in the area were on granite rock terrain, similar to the Hulu Klang area where deadly landslides had previously occurred.

"However, the two landslides are very different. The slopes in Hulu Klang were cut and reworked to strengthen them. It is basically a cut-and-fill slope. But here, it's the more dangerous vertically cut slope."

Dr Ibrahim called for the study of new design models for hillslopes as the climate change over the past years had resulted in strange weather patterns, such as short bursts of heavy rain.

Read more: 'Vertically cut slope unstable' http://www.nst.com.my/articles/02humy/Article//Article#ixzz1NGPM8fR9

Read more: 'Vertically cut slope unstable' http://www.nst.com.my/articles/02humy/Article//Article#ixzz1NGPEHRgf

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