MANILA, July 2 (Xinhua) -- Evacuations of families living close to an island volcano in Batangas province, 66 km south of Manila, were underway on Friday, a day after the phreatomagmatic eruptions that sent "a dark grayish plume" skyward.

"Evacuation activities in high-risk villages as well as in other nearby municipalities in the province are ongoing," presidential spokesperson Harry Roque said in a statement.

Roque said that the government has deployed military and police forces and vehicles to help move the affected residents away from the danger zone.

"We ask residents in the areas surrounding the volcano lake to remain vigilant, take precautionary measures, cooperate with their local authorities should the need for evacuation arise," Roque added.

Mark Timbal, the National Disaster Risk Reduction and Management Council spokesperson, said nearly 1,400 villagers in several towns have been evacuated since Thursday. The number of affected villagers could rise if unrest intensifies.

Thursday's explosions occurred while villagers were still recovering from the January 2020 eruption that blanketed the province and nearby areas with ash.

The Philippine Institute of Volcanology and Seismology (Phivolcs) raised the alert level to 3 on a scale of 5 on Thursday after "a short-lived phreatomagmatic eruption occurred at the main crater" ejecting "a dark grayish plume that rose 1,000 meters."

The institute recorded four more "short phreatomagmatic bursts" on Thursday night, ejecting "short jetted plumes that rose 200 meters above the main crater lake.

"We expect a similar style of eruptions, but it is also possible that a larger explosion can happen, larger than Thursday," Phivolcs Director Renato Solidum said.

Solidum said the institute is closely monitoring if new magma will ascend from below, triggering "very explosive eruptions" similar to last year.

A phreatomagmatic eruption happens when magma and cooler water interact, triggering an explosion.

Since Thursday's eruptions, the institute also monitored several volcanic earthquakes and high levels of volcanic sulfur dioxide gas emissions and steam-rich plumes that rose as much as 3,000 meters high.

"Magma extruding from the main crater could drive explosive eruption," the institute warned.

In January 2020, the eruption of the Taal Volcano in Batangas province affected over 500,000 people and caused billions of dollars in direct damage to infrastructure and agriculture in the provinces of Cavite, Laguna, Rizal and Batangas.

Taal Volcano is one of the 24 active volcanos that dot the Philippine archipelago.

Located along the "Pacific Ring of Fire" and the Pacific Cyclone Belt, at least 60 percent of the Philippines' total land area is exposed to multiple hazards such as frequent earthquakes, floods, tsunami, landslides, volcanic eruptions, cyclones and annual monsoons.