File photo: Xinhua

The Philippine Institute of Volcanology and Seismology on Wednesday raised the alert level over Mount Kanlaon volcano in the central Philippines, saying the volcano has "entered a period of unrest."

The institute said it declared alter level 1, saying that the volcano on Negros Oriental province in the country's Visayas region "is at an abnormal condition and has entered a period of unrest."

The institute also reported that it has recorded a total of 80 volcanic earthquakes since March 9, "dominated by 77 low-frequency events that are associated with magmatic fluids beneath the edifice."

"The increased seismic activity could be succeeded by steam-driven or phreatic eruptions at the summit crater, despite the absence of visible degassing or steaming from the active vent this year," the institute warned.

Since 2017, the institute said it has observed ground deformation that indicates "a period of long-term slow inflation of the edifice." Moreover, it said "short-term electronic tilt monitoring on the southeastern flanks recorded slow inflation of the lower slopes since May 2019 and pronounced inflation of the upper slopes in the end of January 2020."

"These parameters indicate that volcanic processes are underway deep beneath the edifice that may be caused by deep-seated degassing or hydrothermal activity or magmatic intrusion," the institute said.

The institute strongly reminded the residents around the volcano not to enter the 4-kilometer radius permanent danger zone, warning "the possibilities of sudden and hazardous steam-driven or phreatic eruptions."

The institute also wanted pilots to avoid flying close to the volcano's summit "as ejecta from any sudden phreatic eruption can be hazardous to aircraft."

In January this year, Taal volcano in the country's main Luzon island erupted, displacing thousands of residents in the province and nearby provinces.

An active earthquake zone, the Philippines has frequent seismic activity due to its location along the Pacific "Ring of Fire."

The Philippine archipelago is dotted with at least 24 active volcanoes. The country is also lashed by around 20 typhoons each year.