Phivolcs said it maintained the alert status raised last October for Taal, last March for Kanlaon, and last year for Mayon because these volcanoes continue to show signs of activity.

Mayon, it said, is still at Alert Level 2, while Taal and Kanlaon remain at Alert Level 1.

Since the alert status of Mayon is still at Level 2, experts advised the public to keep out of the six- kilometer Permanent Danger Zone (PDZ), particularly in the southeast sector, where volcanic flows and falling and rolling debris may be produced due to possible explosions.

Although Phivolcs was able to see crater glow and volcanic earthquakes in the previous weeks on Mayon, observations made within a 24-hour period showed obscured crater glow and the absence of volcanic earthquakes.

In Kanlaon and Taal, only four volcanic earthquakes were recorded. Phivolcs recorded only one volcanic earthquake in Kanlaon and three-high frequency volcanic earthquakes in Taal.

Aside from the volcanic tremor, seismologists noted ash-laden steam clouds coming out of Kanlaon that had a height of 200 to 800 meters. None was observed for Taal.

Due to these developments, Phivolcs maintained its four-kilometer PDZ for Kanlaon, citing the possible occurrence of hazardous steam-driven explosions on the Negros volcano.

The main crater of Taal, however, is also still off-limits because of sudden steam explosions that may occur or the high concentration of toxic gases that accumulate on the volcano.

Phivolcs said it is continuously monitoring the activities of the three volcanoes.