ILOILO City – A series of tremors hit parts of Iloilo and Antique provinces late night of Oct. 15 until yesterday morning.
In a span of almost 10 hours, the Philippine Institute of Volcanology and Seismology (Phivolcs) recorded 11 earthquakes between 10:47 p.m. on Thursday and 8:41 a.m. on Friday.
These small-magnitude earthquakes confined in almost the same area are called “earthquake swarm,” according to Elmer Relota of Phivolcs-Antique.
Most of these, though, were hardly felt in Iloilo City.
But it can actually last up to one or two weeks and usually would not be over magnitude 5, said Relota.
Magnitude measures the energy released at the source of the earthquake. It is determined from measurements on seismographs.
According to Relota, all the quakes were tectonic in nature.
Tectonic earthquakes are the result of rocks breaking along a fault in the earth’s crust where the strain has built up to a point where the rocks snap and shake.
Data from Phivolcs showed the following earthquakes occurrences:
* 10:47 p.m. Oct. 15, 2020 – magnitude 2.8 in 007 km S 69° E of Anini-y (Antique)
* 10:48 p.m. Oct. 15, 2020 – magnitude 4.1 in 026 km S 36° W of Miag-ao (Iloilo)
* 10:49 p.m. Oct. 15, 2020 – magnitude 3.5 in 018 km S 24° W of Miag-ao (Iloilo)
* 11:13 p.m. Oct. 15, 2020 – magnitude 3.5 in 016 km N 79° E of Anini-y (Antique)
* 1:11 a.m. Oct. 16, 2020 – magnitude 3.0 in 020 km S 29° W of Miag-ao (Iloilo)
* 2:14 a.m. Oct. 16, 2020 – magnitude 3.2 in 026 km S 68° W of San Joaquin (Iloilo)
* 2:20 a.m. Oct. 16, 2020 – magnitude 2.8 in 021 km S 24° W of San Joaquin (Iloilo)
* 2:40 a.m. Oct. 16, 2020 – magnitude 2.5 in 024 km S 29° E of San Joaquin (Iloilo)
* 8:27 a.m. Oct. 16, 2020 – magnitude 4.5 in 013 km S 18° E of San Joaquin (Iloilo)
* 8:32 a.m. Oct. 16, 2020 – magnitude 4.4 in 020 km S 46° W of San Joaquin (Iloilo)
* 8:41 a.m. Oct. 16, 2020 – magnitude 4.4 in 022 km S 62° W of San Joaquin (Iloilo)
As of this writing, there were no reports of liquefaction or ground ruptures./PN