Phivolcs: 3 quakes rock Mindanao in an hour

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.

Magnitude-5.7 quake hits Surigao, causes damage, prompts evacuation

A magnitude-5.7 quake hit the Surigao area in Mindanao before midnight Thursday, causing a power blackout in at least two towns and prompting the preemptive evacuation of residents in coastal areas.

The Philippine Institute of Volcanology and Seismology (Phivolcs) said damage and aftershocks were expected from the quake, which was recorded at 11:11 p.m. and was tectonic in origin.

It said the quake’s epicenter was 54 km southeast of Surigao City.

Phivolcs said the quake was felt at:

An Intensity VI quake is considered “very strong,” Phivolcs said.

“Many people are frightened; many run outdoors. Some people lose their balance. motorists feel like driving on flat tires. Heavy objects or furniture move or may be shifted. Small church bells may ring. Wall plaster may crack. Very old or poorly built houses and man-made structures are slightly damaged though well-built structures are not affected. Limited rockfalls and rolling boulders occur in hilly to mountainous areas and escarpments. Trees are noticeably shaken,” it said.

In an Intensity V quake described as strong, Phivolcs said, “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.” 

An Intensity III quake is defined as “weak,” an Intensity II quake “slightly felt,” and an Intensity I quake “scarcely perceptible.”

Meanwhile, Phivolcs said at least two predawn quakes hit the Mindanao area after midnight Thursday.

At 12:03 a.m., a magnitude-3.4 quake occurred 10 km northwest of Carrascal, Surigao del Sur. 

At 12:54 a.m., a magnitude-3.7 quake hit at 10 km northeast of Jabonga, Agusan del Norte. Aftershocks were expected.

Power failure, evacuation

Last night’s magnitude-5.7 quake caused a power failure and prompted preemptive evacuation in coastal areas there.

The National Disaster Risk Reduction and Management Council (NDRRMC) said Friday Cantilan and Carrscal towns in Surigao del Sur experienced a total blackout after the quake.

“However, power resumed at around 1:30 a.m. Friday,” it said.

The NDRRMC also said Carrascal town disaster management officials conducted a preemptive evacuation of coastal areas, “for fear of a tsunami occurrence.”

For its part, Cantilan town’s disaster management officials alerted local residents “to be on alert if a call for evacuation is needed.”

A separate report on dzBB radio quoted Phivolcs seismologists as saying the quake damaged some houses.

Philippine National Red Cross Surigao del Sur chapter administrator Adel de Guzman said they are checking local highways for possible damage.

2 more quakes 

At least two more quakes hit Mindanao Thursday night before the magnitude-5.7 quake occurred.

The first measuring magnitude 5.6 occurred at 8:52 p.m., with the epicenter at 240 km southeast of General Santos City.

It was felt at:

At 10:27 p.m., a magnitude-3.3 quake hit at 12 km northeast of Carrascal, Surigao del Sur.

Also, an earlier report said at least three quakes hit Mindanao last Thursday evening in an hour.