By Catherine J. Teves
MANILA, April 27 (PNA) — The country’s volcanology chief sees need for continuous inspection of residential buildings nationwide, particularly the low- and medium-rise ones, to help protect life, limb and property from earthquakes.
“We must focus on such inspection as many residential buildings are non-engineered,” Philippine Institute of Volcanology and Seismology (Phivolcs) Director Dr. Renato Solidum said after a magnitude 7.8 killerearthquake struck Nepal last April 25.
He cited need for action as the United Nations said initial figures from its Office for the Coordination of Humanitarian Affairs and from the Nepalese government indicate the earthquake already left some 2,200 people dead and 5,800 others injured.
Solidum said like earthquake-prone Metro Manila, Nepal isundertaking preparations for possible occurrence of major tremors.
“The problem is Nepal has more weak buildings – and some of these are even historical – so many of such structures collapsed from the earthquake,” he said.
He urged local government units (LGUs) nationwide to further spearhead inspection of buildings in their respective areas of jurisdiction so the structures can either be condemned already or strengthened using engineering interventions.
“LGUs must inspect all buildings, especially low- and medium-rise residential ones, as these are where many people live,” he said.
Earlier, Phivolcs and its partners developed a free tool for helping people undertake rapid assessment of their houses’ integrity and vulnerability to earthquakes.
Initial result of the tool “How Safe is My House?” will verify if a house was built following appropriate construction procedures and measures and if it needs strengthening, said Phivolcs.
“Integrity and safety of a house depends on how it was made,” Phivolcs noted.
Ground movement during earthquakes differs depending on distance from these tremors’ epicenter and condition of areas’ rock foundation, said Solidum.
“If an earthquake is near our area, we’ll feel fast ground movement — upwards then horizontally,” he said. “Because of such movement, the tendency for buildings is to move. However, low- and medium-rise buildings will respond most to such ground movement.”
Areas farther from earthquakes’ respective epicenters will experience slower, swaying ground movement, he continued.
“The tendency is for higher buildings to move,” he said.
He noted such happened in Nepal’s capital Kathmandu where such buildings and other tall structures collapsed from last week’s killer earthquake in that country.
“That earthquake’s epicenter was about 50 kilometers away from Kathmandu so the worst-case scenario for that city didn’t happen, however,” he clarified.
Phivolcs continues warning about possible onslaught of a major quake from movement of West Valley Fault (WVF) which stretches across Metro Manila from Quezon City to the cities of Marikina, Pasig, Makati, Taguig and Muntinlupa as well as Pateros municipality.
Authorities reported WVF can generate earthquakes of magnitude 7.0 or stronger.
WVF is already ripe for movement, Phivolcs warned earlier.
”Recent studies show WVF has moved four times and generated strong earthquakes within the last 1,400 years,” Phivolcs and other agencies reported in the 2002-2004 Metro Manila Earthquake Impact Reduction Study (MMEIRS) executive summary.
The agencies also reported in MMEIRS approximate return period of those earthquakes was less than 500 years and no event along WVF is known after 17th century, indicating “active phases of the Valley Fault is approaching.”
“All buildings in Metro Manila must therefore be strong,” Solidum said.
He also reiterated his call for regularly conducting earthquake drills so people will know what to do when tremors strike.
Authorities concerned reported dozens of aftershocks occurred in Nepal after the April 25 killer earthquake there.
Such aftershocks included a magnitude 6.7 earthquake on April 26, they said.
“Thirty-five of 75 districts are affected in the Western and Central Regions, including the Kathmandu Valley districts,” UN said, citing available data.
The most affected districts are Dhading, Gorkha, Rasuwa,Sindhupalchowk, Kavre, Nuwakot, Dolakha, Kathmandu, Lalitpur, Bhaktapur and Ramechhap, UN added. (PNA)