For the first three days of February, Phivolcs said 13 earthquakes have already been recorded. The Philippine National Seismic Network has listed the event parameter (hypocenter, time and magnitude) with the intensity based on the Phivolcs Earthquake Intensity Scale.
Phivolcs director Renato Solidum had earlier said that earthquakes occur daily in small scales. Of the 87 tremors recorded in January, eight were in the magnitude of 5 or higher in the Richter Scale. The strongest was a magnitude-5.9 that occurred 55 kilometers northeast of Mercedes, Eastern Samar on Jan. 17 at 8:55 p.m.
Earlier on that same day at 6 p.m., a 5.1 magnitude tremor hit an area 29 km northeast of Don Marcelino, Davao del Sur. The next strongest was a magnitude 5.5 that hit 62 km southeast of Virac, Catanduanes on Jan. 28 at 8:17 a.m. At noon on that same day, a 5.0 earthquake occurred at 38 km northwest of Calayan, Cagayan. Another 5.5 quake occurred 41 km northwest of Calayan, Cagayan on Jan. 15. Other quakes of the scale of magnitude 5 were: 5.0 that hit 10 km southwest of Talacogon, Agusan del Sur on Jan. 12; 5.0 at 103 km southwest of Sarangani, Davao del Sur, and 5.3 on Jan. 24 at 8 km northeast of Barobo, Surigao del Sur.
Of the 13 earthquakes that occurred during the first three days of February, the strongest had an intensity 5 recorded at 38 km northeast of Borongan, Eastern Samar on Feb. 1 at 12:30 p.m. All of these earthquakes were of tectonic origin. In November 2011, a total of 95 quakes were recorded, of which 21 were felt at various intensities.
The strongest was recorded at magnitude 6 on Nov. 30 at 8:27 a.m. at 100 km northwest of Palauig, Zambales. The others were 5.2 on Nov. 7 at 32 km southwest of Malaybalay, Bukidnon, and 5.1 on Nov. 6 at 7.27 a.m., 58 km. southwest of Dulawan, Cotabato.
For December 2011, 83 quakes were recorded, of which 15 were felt at varying intensities. The highest was 5.4 on Dec. 23 at 12:27 p.m., recorded at 35 km southwest of Mamburao, Occidental Mindoro, and 5.1 on Dec. 27 at 4:34 a.m., 40 km east of Tandag, Surigao del Sur. Solidum said the Phivolcs information on the occurrence of earthquakes daily is "for the public to let them know that minor earthquakes are occurring daily."