Earlier reports disputed; Baguio generally safe from landslides: MGB

BAGUIO CITY -- The Cordillera regional office of the Mines and Geosciences Bureau clarified earlier media reports saying this summer resort city is 90 percent landslide prone, saying the figure is actually a summation of “landslide susceptibility” mapping conducted here .

Engineer Samuel T. Paragas, Cordillera MGB director said “the Office (MGB) has not officially released a statement indicating that the city is 90 percent high landslide susceptible. The approximation may have been taken out of context which may explain why an earlier news report said only 10 percent of the City of Baguio is safe.”

“Generally, Baguio is safe. However, we should always look at the risk or the probability of geohazard occurrences,” he added.

Engineers Zards Gacad, chief of the mine environment and safety division of MGB-Cordillera said “the hazard map prepared by the Office (MGB) does not pinpoint critical areas only. The map indicates several classifications such areas as high landslide susceptible, medium/moderate landslide susceptible and low landslide susceptible.”

“Assuming that the 90 percent estimate is an accurate figure, this then would show that at least 10 percent covers areas with low landslide susceptibility, while the 90 percent would be divided into the critical, high and medium landslide susceptibility classifications,” he said.

“This does not mean that the area covering 90 percent of the city is not fit for habitation. With the appropriate engineering designs and interventions such as firm and solid foundations, benching, retaining walls, proper drainage system, the areas classified as medium, moderate” and even high could still be feasible for habitation,” Gacad added.

He said, in comparison, without proper designs, structures in areas classified as low or medium landslide susceptible may be adversely affected by landslides. “What is important is not the hazard alone, but how this hazard interacts with the various man-made or natural factors in the environment that would increase, or even decrease, the risk of the occurrence.”

Benigno Espejo, supervising geologist of the regional MGB said “high landslide susceptible and critical areas” are unstable areas, significant portions of which are affected by mass movements where human initiated effects are usually high.

Such areas, he added, are unstable areas with the presence of active or recent landslide, numerous and large tension cracks, areas with drainage systems prone to debris damming with numerous old landslides/escarpments, steep slope and proximity to fault structures.

The hazard mapping program of the MGB has 1:10,000 scale hazard maps. The MGB hopes to generate more detailed and smaller scaled hazard maps in the future.

However, the present 1:10,000 scale maps are useful guides for the planning and design of structures and for zoning purposes.

MGB officials said for land development of housing projects including other major land development projects, a more detailed geohazard mapping should be conducted on the area, a requirement prior to issuance of permits.

Subdivision developers are required to undergo geohazard asessment for their specific subdivision project in the same manner that Townsite Sales Applications and Building Permit Applications (in the Municipality of La Trinidad, Benguet) are required to submit specific geological reports prior to the issuance of permits or clearances.