THE Mines and Geosciences Bureau (MGB) said the landslides in Biliran province in December 2017 was caused by heavy downpour and unstable soil, not by mining activities.
“Geologists have not come across any ongoing or remnants of previous open pit mining or quarrying activity within the vicinities of the landslide areas that may have contributed to such occurrence of landslides,” said MGB Eastern Visayas Information Officer Celeste Faith De la Cruz on Monday.
The landslides, which occurred after Tropical Storm Urduja dumped heavy rains in the province mid-December, buried several people alive. At least 42 people were confirmed dead and 14 others went missing, said the Biliran provincial disaster risk reduction and management council.
The weather disturbance also displaced 22,535 families or 90,000 persons in Biliran province alone.
De la Cruz tagged some factors that contributed to soil erosion based on their assessment conducted on December 28, 2017.
The mudslide was largely attributed to the intensely weathered, fractured, and altered volcanic with clay-like materials underlying the areas, said the MGB.
“Continuous heavy rainfall brought about by storm Urduja, which loosened the topsoil with boulders and uprooted the trees,” said De la Cruz in a phone interview on January 8.
The landslide-hit areas, according to MGB, had a slope gradients of 45 percent (very steep), making the areas highly susceptible to erosions.
The presence of "points of weaknesses" along road cuts and riverbank portions also contributed to the landslide.
These "points" include fractures and deteriorated rocks.
“Another factor is the unstable grounds due to road development, farming, and poor drainage system,” said De la Cruz.
Biliran is one of the country's smallest provinces with a land area of 536 square kilometers and a population of 171,612 as of 2015. (PNA)