Solidum doubts liquefaction caused tilting of Manila school building after Luzon quake

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MANILA - The tilting of the Emilio Aguinaldo College in Manila following Monday's 6.1-magnitude Luzon earthquake may not be due to soil liquefaction, the country's chief seismologist said Saturday.

"Wala kaming na-receive na report na bumitak 'yung kalsada, may lumabas na tubig---‘yun po 'yung sense ng liquefaction," Phivolcs chief Renato Solidum said on DZMM.

(We did not receive any report about the ground breaking, or water coming out---that's the sense of liquefaction.)

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According to the United States Geological Survey, liquefaction takes place when loosely packed, water-logged sediments at or near the ground surface lose their strength in response to strong ground shaking.

Solidum said if the magnitude 6.1 earthquake did soften the soil, then the effect should have been widespread.

"Baka ang isyu diyan ay 'yung foundation. Dapat tingnang mabuti gaano ba kalalim 'yung paa nito, at ano ba ang design ng kaniyang basement para ma-prevent ang ganyang pangyayari lalong-lalo na kung may malakas na lindol kasi liquefaction-prone ang lugar na 'yun," said Solidum of the building in Paco, Manila.

(Maybe the issue there is the foundation. They should look into how deep the foundation is and the design of the basement to prevent something like this from happening, especially when there's a strong quake because the area is liquefaction-prone.)

Solidum added that other buildings around the area were not affected by the quake.

Buildings are supposed to sway after an earthquake and return to their original vertical position, experts earlier said.

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Photos that circulated online showed that the school was left leaning on an adjacent structure in the wake of the 6.1-magnitude earthquake that was also felt in Metro Manila.

Although there are many parts of the metro where the soil is soft like in Marikina Valley and coastal cities, Solidum said they did not expect liquefaction to happen at an Intensity 5 temblor.

He said engineers and building officials should check if the building is still advisable to use.

"Kung wala 'yung building na katabi, baka tumagilid pa lalo," he said.

(If not for the other building, it could have tilted more.)

However, the tilting could also cause some stress on the other building.

"So dapat tingnan din ng both building owners at building officials kung anong epekto 'yung pagkasandal ng building doon sa tibay ng gusaling 'yun," he said.

(That's why both building owners and officials should look into the effect the leaning building has on the other building's integrity.)

Metro Manila was among areas that shook when a magnitude 6.1 earthquake struck Luzon, with its epicenter in Castillejos, Zambales.

Severely affected was Pampanga, where a four-story supermarket collapsed, killing five. The temblor left a total of 16 people dead and several injured.

• Luzon quake death toll climbs to 16