The Mines and Geosciences Bureau (MGB) 7 has recommended the continuous monitoring of mass movement and relocation of a house at the lower section of the slope following a vertical displacement of less than one meter ground cracks in Sitio Sagrada, Barangay Alpaco, Naga City south Cebu.
A team of geologists composed of Al Emil G. Berador and Josephine T. Aleta conducted a site assessment last February 24 and recommended the provision of a cross drain from spring towards the creek down slope, and coordinate with the Department of Public Works and Highways (DPWH) for proper engineering design of drainage and road repair.
To caution the communities of the danger of the affected area, it also recommended to put up an early warning or a signage as it is rated as highly susceptible to landslides, and maintain a free-flowing condition of creek to prevent water ponding, scouring, and saturation of its bank.
MGB-7 Regional Director Loreto B. Alburo said mass movements such as landslides on slopes are usually aided by water, weathering or erosional debris cover on slopes, and the character and structure of rocks.
The assessment revealed that ground cracks extend an approximate length of 30 meters with mostly earth or fine and clayey materials. It was also a rotational slide in which the surface of rupture is curved concavely upward and the slide movement is roughly rotational about an axis that is parallel to the ground surface and transverse across the slide.
A landslide threat advisory was issued last February 24 on the results of the assessment including the recommendations, which was received by Barangay Captain Rolando Jurado.
The incident was attributed to the combination of several factors such as heavy rainfall, the type of soil being mostly clayey, presence of ground cracks which become bigger due to the 6.9 magnitude earthquake and aftershocks.
Alburo advised residents near the affected area to exercise extra caution and initiate readiness and measures to prevent potential damage to lives and properties.
He also added that the susceptibility rating of high was arrived during the field assessment and it should be pointed out that the rating could advance to high to very high.