Business MirrorPublished on Wednesday, 20 March 2013 19:10
ORMOC CITY—The Mines and Geosciences Bureau (MGB) said immediate slope stabilization and rehabilitation measures must be established as a non-structural blockade to flooding at a landslide-damaged area in Upper Mahiao, Lim-ao, neighboring Kananga town in Leyte.
Aside from this recommendation, the MGB also pushes for the construction of dikes, retaining walls, groins and breakwater to prevent floods during heavy rains and typhoons. The MGB has identified the cause of the landslide at Pad 403 on March 1 to the overlying weak materials coupled with a very steep slope surrounding the mountain.
MGB Supervising Geologist Ceferino de la Cruz said the slope gradient in the area is measured at 52” which is considered very high based on the landslide susceptibility rating parameters of their bureau.
“This is especially so because the slope is underlain by intensely weathered, fractured and altered volcanic rock exhibiting sulfide or iron staining with clayey materials,” he said.
Historical records of old landslides, presence of escarpments and tension cracks are manifestations of inevitable landslide, he went on. The landslide area has an MGB rating of high susceptibility to landslide and not prone to flooding per geo-hazard mapping and assessment survey conducted in May 2006.
De la Cruz said the area and its immediate vicinity has experienced landslide occurrences sometime in January and on Sept. 25 and 26, 2009, which resulted to surface and ground cracks at about 15 meters upslope that could have possibly led to mass movement.
He underscored that the EDC must conduct mandatory assessment of areas and periodically monitor the potential geohazards being manifested in the grounds. The lack of monitoring was evidenced by the weak materials along the very steep slope surrounding the mountain where the steam pipeline is laid with high probability of being hit by an inevitable landslide.
De la Cruz further noted that the vegetation cover is not enough to ensure a landslide environment. He thus called on the company to conduct a strict monitoring of ground degradation relative to landslide occurrence. source
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