At least three quakes, the most powerful measuring a “strong” magnitude 4.5, rocked parts of Mindanao in the span of an hour Thursday evening.
The Philippine Institute of Volcanology and Seismology (Phivolcs) said no damage was expected from the quakes, although it warned of possible aftershocks.
It said the first quake measuring magnitude 4.5 was recorded at 5:09 p.m., with the epicenter at 12 km northwest of Carrascal, Surigao del Sur.
The first quake was tectonic in origin and was felt as Intensity V in Cantilan and Carrascal, Surigao Del Sur; Intensity III in General Luna, Surigao del Norte; and Intensity II in Soccoro and Bacuag, Surigao del Norte.
Phivolcs defines an Intensity V quake as “strong.”
“(A strong quake is) generally felt by most people indoors and outdoors. Many sleeping people are awakened. Some are frightened, some run outdoors. Strong shaking and rocking felt throughout building. Hanging objects swing violently. Dining utensils clatter and clink; some are broken. Small, light and unstable objects may fall or overturn. Liquids spill from filled open containers. Standing vehicles rock noticeably. Shaking of leaves and twigs of trees are noticeable,” it said.
An Intensity III quake is “weak,” and felt by many people indoors especially in upper floors of buildings.
Phivolcs said that in an Intensity III quake, vibration is felt like when a light truck passes.
“Dizziness and nausea are experienced by some people. Hanging objects swing moderately. Still water in containers oscillates moderately,” it said.
It also defined Intensity II as “slightly felt,” or felt by few people at rest indoors.
Aftershocks were expected from the first quake, Phivolcs said.
Two more quakes
The second quake measured magnitude 3.9 and was recorded at 5:27 p.m., with the epicenter at 54 km northwest of Tandag, Surigao del Sur. It was felt as Intensity II in Cantilan, Surigao del Sur, but no damage or aftershock was expected.
The third quake measured magnitude 4.1 and was recorded at 5:41 p.m. Its epicenter was 23 km southeast of Jabonga, Agusan del Norte.
The quake was felt as Intensity II in Cantillan, Surigao Del Sur; and as Intensity I in Soccoro, Dinagat Island
Aftershocks were expected from the third quake.