MGB: Natural, human initiated processes cause landslide in Benito Soliven
Posted: June 23, 2021
Tuguegarao City, Cagayan- A landslide which occurred in Purok Bakikir, Brgy. Yeban in Benito Soliven, Isabela were combined effects of natural and human initiated processes.
This was the initial findings and observations of the team of geologists of Mines and Geosciences Bureau Region II headed by Senior Geologist Oliver Hans H. Lapina together with C/Science Research Specialist Jessa Ammugauan, and C/Geologist II Ma. Ana Claraval on the conducted geological assessment on June 10, 2021.
Bonifacio Viernes, barangay captain of Yeban Norte said during the interview that the area has been experiencing various landslide incidents, but it was during the onslaught of Typhoon Juaning in 2011 when a tension crack started to develop along the residential area and barangay road.
MGB findings cited the underlying lithology of the area is composed dark, brown, highly weathered, unconsolidated sandstone. These types of lithologies are considered weak and may easily be over saturated and eroded.
Moreover, presence of springs and disturbed shallow groundwater level in the area is also a contributing factor that have resulted to increase in water content of the materials that led to the reduced slope stability.
“There were only 50 houses in the area. At present, there are already 95 fully concrete, one to two-storey houses built on top of the possible accumulation zone,” May Florence Abu, municipal disaster risk reduction management officer of Benito Soliven said during the interview.
The construction of fully concrete houses led to the overloading in the area and the unregulated agricultural activities along the slopes have threatened the structural integrity and disturbed the stability of the slope that resulted to a mass movement.
During the assessment, the team which composed of MGB ROII Geologists, MDRRM, and barangay officials of Benito Soliven noted that evidences of mass movement such as rock fall, tension cracks, sudden disappearance of spring water, and sudden reappearance of murky spring water within the vicinity could possibly indicate that the area is still unstable and may still possibly lead to another landslide incident.
Based on the MGB 1:10,000 Scale Geohazard Map, the assessed area in Brgy. Yeban in Benito Soliven is classified as having high susceptibility to rain-induced landslide rating.
With the impact of the landslide, the Bureau recommends for the immediate relocation/evacuation of the residents to a more stable and safer grounds. Locate and control possible accumulation zone of the debris and earth materials that would expose a direct danger to the local community. Establish a proper drainage system that can accommodate the maximum historical run-off values as well as surface run-off that may drain in the area.
Further, debris accumulation zone areas must not be used for community settlement. As these areas will be directly affected by landslides and flash floods.
