Flash floods feared due to artificial dam

TRIGGERED BY LANDSLIDE AFTER QUAKE

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A growing body of evidence suggests that a massive landslide between Barangay Gaway-gaway in San Remigio and Barangay Anonang Sur in Bogo City—triggered by the 6.9-magnitude earthquake that struck northern Cebu late last month—has caused artificial damming, raising alarms over potential flash floods, karst subsidence, and widespread displacement.

The warning came from former Mines and Geosciences Bureau (MGB) chief geologist Liza Socorro Juanico Manzano, following the circulation of photos showing submerged homes and rising water levels in the upland Tigib area.

Manzano explained that artificial damming occurs when landslide debris blocks a river channel, causing water to accumulate upstream.

“If left unaddressed,” she warned, “this can lead to destructive flash floods or debris flows downstream—especially during heavy rainfall, when river energy and sediment loads are elevated.”

She also raised concerns about karst subsidence, a scenario where ponded water infiltrates underground fissures and tension cracks, potentially weakening sinkholes and cave systems. Manzano stressed the need for immediate removal of debris and urged close coordination with MGB Region 7 to assess risks and identify vulnerable communities.