Zamboanga City (CNN Philippines) — The Philippine Institute of Volcanology and Seismology (Phivolcs) has offered an explanation for the series of tremors observed in Zamboanga within recent weeks.
At least three tremors were reported in Zamboanga City for the month of July alone.
Phivolcs Region-9 Officer in Charge Engr. Allan Labayog described the situation as an “earthquake swarm,” a series of tremors which are low in intensity, some of which can not be felt by residents but are recorded by sensitive scientific instruments.
The earthquake swarms are said to be indicative of two things: that plates beneath the earth’s surface may be releasing energy and pressure which is a normal occurrence, or that the plates beneath the earth’s surface may be releasing pressure in preparation for a bigger earthquake with a strong intensity.
Labayog said that there is no way of knowing why the earthquake swarms are happening.
The last earthquake in Zamboanga City was recorded 570 kilometers below the sea, south of the Zamboanga peninsula last July 29. It registered at magnitude 5.6 but was not felt.
Previous to that a tremor was also recorded at magnitude 4.2, 34 kilometers northwest of Sibuco last July 26.
Last July 16, a magnitude-2.0 earthquake hit Zamboanga City. The tremor was also felt in the cities of Dipolog and Pagadian.
