Ground cracks threaten residents of 2 villages in Sarangani

GENERAL SANTOS CITY (MindaNews / 23 July) – The Mines and Geosciences Bureau (MGB) in Region 12 has recommended the relocation of residents in two upland communities in Alabel town, Sarangani province due to the threats posed by active ground tension cracks.

Ariel Austin Acosta, MGB-12 supervising geologist, said Friday the ground cracks were found in portions of Sitios Ulo Latian and Katimbol in Barangay Datal Anggas, which is located near the province’s mountainous boundary with Davao Occidental.

He said the affected areas are considered highly prone to major landslides due to the presence of the tension cracks.

Alabel in Sarangani. Map courtesy of Google

Acosta said they conducted an ocular inspection and assessment of the two sites early this month during the initial leg of their karst subsidence hazard assessment and mapping of the municipality.

“We recommended to the municipal government the identification of at least three relocation sites for the affected residents,” he said in an interview.

The Municipal Disaster Risk Reduction and Management Office of Alabel has yet to release the number of affected families but he said the top priority are those situated near the landslide areas and those along the critical roadside communities.

He said more assessments are slated in other areas of the municipality that are considered at risk to similar threats and other related geohazards.

In November 2019, MGB-12 also recommended the relocation of nearly 60 families from portions of Sitio Lilab in Barangay Pag-asa due to the presence of huge tension cracks. It declared the area as a “no build and settlement zone.”

The evacuees have since been relocated by the municipal government to a safer area in Sitio Canaan in the same village.

Acosta said they are set to visit more areas in Alabel in the coming weeks to continue with the karst subsidence mapping, which covers 12 of its 13 barangays.

He said the initiative mainly aims to identify areas susceptible to subsidence due to sinkhole collapse and eventually produce karst subsidence susceptibility maps.

Karst is a type of landscape where the dissolving of the bedrock has created sinkholes, sinking streams, caves, springs, and other characteristic features, an MGB-12 report said.

It said sinkholes are ground depressions or openings formed when the underlying soluble rocks are dissolved resulting in voids underground which can weaken the support for the overlying surface.

During the assessment conducted from June 21 to July 10, the MGB-12 team validated sink depths that are mostly active and inactive landslides, and tension cracks.

“Subsidence due to sinkhole collapse is a dangerous geohazard because of its unpredictability,” the agency said.

The ongoing karst subsidence mapping in Region 12 (Soccsksargen) already covered Maasim town in Sarangani, Lake Sebu in South Cotabato, and Lebak in Sultan Kudarat, with at least 100 sinkholes so far identified. (MindaNews)