How safe is your house from quakes? Take the Phivolcs test

HOW safe is your house from earthquakes?

Geologist Jeffrey Perez, supervising science research specialist of the Philippine Institute of Volcanology and Seismology (Phivolcs), asked Digos barangay officials 12 simple questions to help them determine how safe their houses are, even as he explained the series of powerful quakes that they experienced in the last two months, debunked myths and misconceptions, and raised their awareness on how safe – or unsafe – their houses are.

By their responses, most of the barangay officials who attended the “Earthquake 101” lecture flunked the house safety test.

Perez asked who among them secured a building permit when they constructed their houses.

“Who secured building permits?” Perez asked. No hands were raised. “None? That is dangerous.”

He explained that if they follow the National Building Code, their houses won’t collapse even if it is Intensity 8.

He said many houses near the epicenters of the quakes were destroyed because they used four-inch hollow blocks instead of the standard six and steel bars less than the standard 10 mm.

Also, he said, there should be a post every three meters to ensure the house won’t collapse.

The safety checklist:

Question 1: Who built or designed your house? If your answer is a licensed civil engineer or architect, you get one point.

Question 2: How old is your house? If built after 1992, you get one point.

Question 3: Has your house been damaged by past earthquakes or disasters? If the answer is no, or “yes but repaired,” you score one point.

Question 4: What is the shape of your house? If the answer is “regular” or symmetrical, rectangular, box-type, simple, that’s another point.

Question 5: Has your house been expanded or extended? If the answer is no or “yes but supervised by a civil engineer or architect,” you score a point.

Question 6: Are the external walls of your house six-inch (150 mm) CHB? If yes, you get another point. I

Question 7: Are steel bars of standard size and spacing used in walls? If you used 10 mm diameter, tied and spaced correctly, you get one point.

Question 8: Are there unsupported walls more than three meters wide? If the answer is “none,” you score a point.

Question 9: What is the gable wall of your house made of? If the answer is “light materials, properly anchored CHBs, no gable wall,” you get another point.

Question 10: What is the foundation of your house? If the answer is reinforced concrete, that’s one point.

Question 11: What is the soil condition under your house? If your answer is “hard” (rock or stiff soil), you score another point

Question 12: What is the overall condition of your house? If the answer is “good,” that’s another point.

Perez said a score of 11 to 12 means your house is “okay.” A score of eight to 10 means you need to strengthen your house. A score below eight is “disturbing. Pwedeng masira sa lindol.”

The self-check states that for those scoring 11 to 12 points, “though this seems safe for now, please consult experts for confirmation.”

For those with scores of eight to 10, “this requires strengthening, please consult experts” and for those with scores of zero to 7, “this is disturbing! Please consult experts soon.”

In its report on the Dec. 15 quake, Perez’s group recommended that in case of another felt earthquake, do the “drop, cover and hold;” damaged buildings and infrastructure should be inspected by engineers, and should not be used unless assessed as safe; for areas with existing tension cracks, conduct pre-emptive evacuation, and be watchful of landslides triggered by earthquakes and prolonged heavy rainfall; formally train local masons and carpenters on the proper construction practice and use of standard construction materials and reconstruction or construction of houses and buildings should conform with the National Building Code of the Philippines; review and formulation of policies and ordinances that will address the gaps in the issuance of building permits and monitoring of building constructions; and national and local government units in collaboration with non-government agencies should provide psychosocial support such as stress-debriefing to affected communities.

The house safety test can be downloaded from the Phivolcs website.

Perez also urged barangay officials to visit hazardhunter.ph which can provide seismic hazard assessment (nearest active fault from your home or office, susceptibility to ground rupture, ground shaking, earthquake-induced landslides, liquefaction, and tsunami), volcanic hazard assessment (nearest active volcano, nearest potentially active volcano, nearest inactive volcano), and hydro-meteorological hazard assessment or susceptibility to flooding, landslides, storm surge, severe winds.

The self-check for earthquake safety of Phivolcs is in collaboration with the Association of Structural Engineers in the Philippines (Asep) under the Japan International Cooperation Agency-Japan Science and Technology Agency project on the “Enhancement of Earthquake and Volcano Monitoring and Effective Utilization of Disaster Mitigation Information in the Philippines.”

It helps owners understand and evaluate the integrity of their houses and their vulnerability to strong earthquakes.

The self-check is initially intended for one to two-story CHB houses, including residences with small shops, offices, garages and the like, to help owners evaluate their houses by themselves and understand the likely behavior of their houses during a strong earthquake.

It’s not a new test. It first came out in February 2014 or nearly six years ago but interest in it is just starting to gain ground in Mindanao due to the series of above Magnitude 6 quakes in two months – 6.3 on Oct. 16, 6.6 and 6.1 on Oct. 29, 6.5 on Oct. 31 and 6.9 on Dec. 15 – and largely through Phivolcs’ information and education campaigns, particularly in the quake-hit areas. (Carolyn O. Arguillas, Mindanews)