Landslide threats in Lapu; ‘Liquefaction’ in Mandaue

Slopes loosened by Tuesday’s 7.2-magnitude earthquake has threatened households in barangay Pusok in Lapu-Lapu City.

In Mandaue City, grayish mud oozing out of ground fissures that formed after the earthquake may indicate liquefaction.

The Lapu-Lapu City Engineering Office headed by Allan Pedrigal warned people living near a 30-feet deep cliff to leave the area after a big boulder was dislodged following Tuesday morning’s earthquake.

A smaller landslide also occurred at another cliff about 20 meters away putting houses on top in jeopardy.

Pusok barangay Captain Tranquilino Omolon Jr. issued a warning to residents to leave the area but only a few heeded his call.

Andy Berame, City Risk Reduction Council member, said they asked the DENR Mines and Geo-sciences Bureau (MGB) to check the area in barangay Pusok.

Berame also asked the MGB to check the sinkhole in barangay Canjulao. Pedrigal’s team went to the sinkhole yesterday afternoon and cordoned off the 15-feet wide hole.

An MGB geologist said they have sent teams to conduct a posthazard assessment in landslide sites and sinkholes.

Liza Manzano a geologist of the MGB said at a briefing at Camp Aguinaldo yesterday that areas affected by sinkholes include Lapu-Lapu in Cebu, Loon, Calape, Pemandangan and Tubigon in Bohol.

Manzano also hoped for clear weather as rain could aggravate conditions making it more hazardous.

“Earthquake-induced landslides, rockslides could be converted into debris flow…then it would be rain-induced [landslides],” Manzano said.

Liquefaction

Meanwhile, gray mud or fine sand coming out of ground cracks in the Mandaue City abattoir and city jail might be sand boils or volcanic sand that surfaced during the ground shaking.

“I think nagkaroon ng liquefaction in areas underlain with fine and loose sediment where the water table is shallow. Kaya during ground shaking lumalabas itong mga sand boils,” Manzano told Cebu Daily News.

She, however, added this has to be studied further.

“Nahadlok mi aning sitwasyona kay basin ug dunay sinkhole dinhi sa ilawom,” said Dr. Daisy Penetrante, the Mandaue City veterinarian.

Work goes on inside the slaughterhouse building, which was able to withstand the earthquake.

Dr. Nestor Taasan, the head of the slaughterhouse, also expressed apprehension. “Considering there are cracks in the ground, there could be a possibility that the ground is weak or has a cavity that endangers the building as well as the personnel.”

At the Mandaue City Jail, Warden Jessie Calumpang said, “We were shocked to see the clay oozing out of the cracks in the ground. We are frightened there might be a sinkhole.”

No major damage was found in the prison building, though. The building is overcrowded with over a thousand inmates. It was built to accommodate 1,000 detainees. The MGB has yet to investigate this phenomenon. /with Inquirer reports