A house pancaked by the earthquake in Padada on the southern Philippine island of Mindanao
A house pancaked by the earthquake in Padada on the southern Philippine island of Mindanao AFP / FERDINANDH CABRERA

An earthquake of 6.9 magnitude struck Davao del Sur near Davao City, where Philippine President Rodrigo Duterte was staying, Sunday. The president and his daughter Kitty were unharmed as was First Lady Honeylet Avanceña, who was on her way home when the quake occurred. Presidential Security Group Chief Brigadier General Jose Niembra said Duterte went back to sleep after the shaking stopped.

Presidential Spokesperson Salvador Panelo urged residents to remain calm but to be wary of aftershocks that often follow stronger quakes. He asked the public not to spread disinformation that may cause undue panic among affected communities.

The president’s house had already sustained some minor damage in the form of cracks from previous earthquakes and is currently being assessed for any structural damage from the latest one.

The Philippine Institute of Volcanology and Seismology (PHIVOLCS) recorded the earthquake around 2:11 p.m. (1:11 a.m. EST) and traced its epicenter nine kilometers northwest of Matanao, Davao del Sur.

Mantanao and Magsaysay felt the full brunt of the temblor with outlying areas getting less of a jolt. The southern tip of Mindanao, Zamboanga del Sur experienced only a 1 magnitude recorded shaking.

The Richter Scale was developed in 1935 by American seismologists Charles F. Richter and Beno Gutenberg. It is a logarithmic scale meaning that an increase in one full digit is a 10-fold increase in intensity. For example, a magnitude 5.0 on the Richter scale will cause some damage to weak structures. A magnitude 6.0 is 10 times stronger and will cause moderate damage while a magnitude 7.0, at 100 times the strength of a 5.0 quake, can cause widespread damage and loss of life.

The area, much like the well-known San Francisco Bay Area in the U.S., is a known seismic hot spot. Three recent quakes measuring in the 6.3 to 6.6 magnitude have struck areas in Tulunan on the 16th, the 29th and the 31st of October. The 1989 Loma Prieta quake in the SF Bay Area measured at about 7.0 and killed 63 people. Some victims were crushed when the freeway collapsed creating a “pancake” effect on the vehicle and its occupants.

Duterte may be able to sleep after an earthquake but the rest of the populace should heed the recommendations made by Defense Secretary Delfin Lorenzana and NDRRMC chairperson Undersecretary Ricardo Jalad. They recommended the conduct of more safety drills to raise awareness and prepare the public for future disasters.