(PNA file photo)

MANILA -- Four volcanic tremors that lasted 2 to 7 minutes were detected in the Taal Volcano for the past 24 hours, the Philippine Institute of Volcanology and Seismology (Phivolcs) said Tuesday.

"The tremors are volcanic earthquakes signifying fluid or gas movement," Phivolcs Director Renato Solidum Jr. told the Philippine News Agency.

He added that these tremors have no relation to the magnitude 7 earthquake that jolted northern Luzon last week.

Alert Level 1 (low-level unrest) stays, Solidum said.

Under Alert Level 1, sudden steam-driven or phreatic explosions, volcanic earthquakes, minor ashfall and expulsions of volcanic gas could threaten areas within Taal's permanent danger zone.

Entry into the permanent danger zone, especially the vicinities of the main crater and the Daang Kastila fissure, remains prohibited. Occupancy and boating on the Taal Lake are likewise prohibited.

Pilots are also urged to avoid flying close to the volcano as airborne ash and ballistic fragments from explosions and wind-remobilized ash may pose hazards to the aircraft.

For the past 24 hours, a voluminous plume emission reaching 1,200 meters high was also observed.

Sulfur dioxide flux averaged 2,306 tons on August 1, Phivolcs said. (PNA)