In just the past week, a total of three earthquakes rocked Metro Manila and nearby provinces. One occurred last April 4, and two were felt last Saturday, April 8. The epicenters were in the province of Batangas and ranged from magnitude 4 to 6.
By definition from the United States Geological Survey, the measurements mean that the lightest earthquake, which was a magnitude 4.1, could be felt by many indoors. The strongest, a magnitude 6, could cause moderate damage to well-built ordinary structures, but it would cause considerable damage in poorly built or badly designed structures.
The earthquakes brought to mind a statement that the Philippine Institute of Volcanology and Seismology (PHIVOLCS) made last May 2015. The organization said the Philippines was due for a devastating magnitude 7.2 earthquake from the West Valley Fault that runs through Metro Manila.
PHIVOLCS director Renato Solidum clarified, however, that movement in the Lubang Fault, which is not related to the West Valley Fault, caused the three recent earthquakes, he told The Philippine Star and Rappler. He added that it was not unusual for earthquakes to occur just a minute apart in the same area.
The Malacañang has urged the public to stay calm but remain vigilant and alert. Now, more than ever, preparedness is vital. Aside from being prepared with your family’s emergency kits, you need to check the stability of your home.
Back in 2015, PHIVOLCS, in partnership with the Japan International Cooperation Agency (JICA), prepared a 12-point questionnaire for homes made of concrete hollow block (CHB) with a maximum of two floors. Entitled “How Safe Is My House,” the simple checklist designates points for every answer to each question. The higher the points you get in the end, the greater the likelihood that your house is earthquake-safe.
According to the information sheet, homeowners should avoid using sand and gravel taken from shorelines and beaches as materials for concrete hollow blocks, mortar, plaster and concrete mix. These are “known to corrode steel bars over time.”
For questions 7 to 10, you may need to consult the builders of your home. Answering with a “not clear or unknown” will lower your total score.
Add up your points and find out your home's eathquake-readiness score:
Whatever your score may be, PHIVOLCS recommends having an engineer to double check the stability of your home. Ask for recommendations as well for affordable or low-cost materials that can strengthen your house (specifically its walls), protect it from collapse, and minimize falling debris during a strong earthquake.