DAVAO CITY, Philippines—A study released by the Mines and Geosciences Bureau blamed the uncontrolled influx of miners in gold rush towns for the high casualties in the landslides that occurred in these mining towns.
“Although these landslides were not so extensive as compared to what happened in Ginsaugon (in Leyte) in 2006, they claim more lives because of the uncontrollable influx of miners in these areas, according to the report by Salvio Lasierna, MGB supervising science research specialist to the MGB central office in Manila.
Lasierna headed the team of geologists who conducted the detailed geohazard maps in the gold rush towns of Compostela and Pantukan towns of Compostela Valley from May 17 to June 13 this year. The survey, which also served as a follow up of the initial assessment of the landslide in the mining areas of Panganason village in Pantukan this year, identified at least six sitios and puroks in the Pantukan Barangay of Napnapan and sitio Panganason of Barangay Kingking for their very high susceptibility to landslides.
In Compostela town, Purok 20 of Barangay Ngan registered a very high susceptibility to landslides while the likelihood of landslides in neighboring areas varied from low, moderate to high.
“Indiscriminate mining by small scale miners contribute largely to landslides in Pantukan area,” said Lasierna in the report.
“The cutting of slopes for the construction of ball mills, siltation ponds and overcrowding of houses within a small area have aggravated the condition of the slopes.”
Aside from the landslide susceptibility rating, the geologists also took note of the location of landslide escarpment, tension cracks, landslide direction and its accumulation zone. The study noted that landslides in Pantukan areas mostly happen in communities close to road projects and mining sites while landslides in Compostela town happen along new road cuts built without slope stabilization measures.
The report said that the most landslide-prone areas in Compostela are mostly confined along steep valley walls and mountain slopes but mining activities confined along flat to rolling topography, are not as susceptible.
The team of geologists also cited that in the Panganason landslide in Pantukan early this year and the Diat landslide in 1986, “majority of the casualties came from neighboring towns.”
“They construct houses and ball mills everywhere without the approval of the municipality,” the report said.
It also cited how mining areas instantly turned into residential communities, complete with electricity, eateries, amusement bars and market, violating the town’s land use zoning.
Among its recommendations, the study asked local officials to strictly enforce their land use plan, regulate the construction of ball mills and tailing ponds to prevent overloading of slopes and seepage that could trigger landslides. It also called on the local government, the mining companies and association of small miners to work together to develop a community away from the mining zone, slope stability measures in landslide prone areas with moderate susceptibility and evacuation sites for areas highly prone to landslides.
The team also recommended the use of the geo-hazard map in the land use planning.