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© Philippine StarSinhole in Cebu. File photo
Mayor Ernesto Uy of Mabinay, Negros Oriental on Wednesday said he is awaiting the initial investigation report of the Mines and Geo-Sciences Bureau (MGB) of the Department of Environment and Natural Resources (DENR) in Region 7 on the formation of sinkholes in the last barangay of that upland municipality.

He explained that the MGB-7's investigation report would be a basis for him to determine future actions of the Mabinay local government unit regarding the sinkholes, considering that the area where they are situated is close to the proposed site for the regional centers of the newly formed Negros Island Region (NIR).

As this developed, the mayor disclosed that as of late Wednesday, he ordered the Mabinay Rescue Group to proceed to the area and monitor the sinkholes following heavy rain earlier in the day.

Last week, at least four sinkholes were found at the Malaiba riverbed with a fifth one having formed over the weekend, spurred by continuous rains and widely perceived to have been caused by what residents believed to have been an earthquake or ground shaking nearby, said Uy.

At least two tension ground cracks were also monitored to have formed around the sinkholes, he added.

According to Mayor Uy, the MGB-7 team that visited the site of the sinkholes at the Malaiba River in Barangay Hagtu, Mabinay told him there could be a larger hole underneath that must have caused the depressions on the surface.

Initial measurements taken by the MGB-7 team showed the biggest of the five sinkholes had measured around eight to nine meters in diameter with a depth of about eight feet, the mayor disclosed.

Other holes measured were around two to three meters in diameter and six to eight feet deep, Uy further disclosed.

The mayor said he believes the sinkholes could have extended farther down from the surface the first time they were observed but rains and flowing water had eroded sediments that gradually filled them up.

Mayor Uy stressed he is very much interested to learn about the MGB-7's initial pronouncement of the possibility of a bigger hole underneath the surface and locating its outlet.

The MGB-7 team is expected to return soon upon the request of the local chief executive for further study of the sinkholes.

Meanwhile, continuous monitoring of the sinkholes is foremost for the Mabinay LGU to avoid future sinkhole formations, the mayor said.

The MGB-7 team had told him that two days of continuous rain would cause a possible collapse of the ground surface.

The site of the sinkholes is located in what many believe to be an earthquake fault along the Hagtu-Tagukon area in the boundary of Mabinay, Negros Oriental and Kabankalan, Negros Occidental.

The purported earthquake fault is said to form part of the Central Negros fault which geologists had earlier reported on.

Tagukon is the adjacent barangay to Hagtu and has been declared the site of the future regional centers of the NIR or Region 18.

Source: Philippines News Agency