Sinkholes expected in quake-hit Cebu

MANILA, Philippines — The emergence of hundreds of sinkholes in quake-hit Northern Cebu is expected, according to Science Secretary Renato Solidum Jr.

“Most of the places in Cebu are made of limestone,” he told radio dzRH on Saturday, “so it’s expected that there could be sinkholes.”

Solidum explained that limestone – used as an aggregate in concrete and road construction – easily melts when water flows through it, leading to sinkholes in areas without roads or drainage systems.

In the event of a strong earthquake, thin sinkhole coverings can be destroyed, according to the science chief.

Region VII of the Mines and Geosciences Bureau has issued a subsidence threat advisory on Friday in Bogo City, Daanbantayan, Medellin, San Remigio and Tabogon due to confirmed sinkholes and land depressions in several barangays.

“The recent seismic activity has destabilized ground conditions, resulting in the formation of sinkholes in certain affected areas,” the advisory reads.

In San Remigio, which experienced intensity seven shaking, Mayor Mariano Martinez said there could be over 100 sinkholes across the municipality.

Solidum said authorities can use ground-penetrating radar to determine if sinkholes extend beneath the areas where houses are built.

They should also fix damaged roads immediately so rescuers can deliver aid to victims unhampered, he added.

Moving forward, Solidum urged local governments to reinforce roads with steel and connect them to drainage systems.

“The road should be connected to the drainage because sometimes, the bottom of it is concave, which is easy to break,” he said.