Alert Level 1 – Low-Level Unrest
No eruption Imminent
Activity may be hydrothermal, magmatic or tectonic in origin. No entry in the 6-kilometer radius danger zone.
Alert level 2 – Moderate Unrest
Could eventually lead to an eruption
6-kilometer danger zone may be extended to 7 kilometers in the sector where the crater rim is low.
Alert level 3 – Relative High Unrest
Eruption is possible within weeks
Extension of the danger zone in the sector where the crater rim is low will be considered.
Alert Level 4 – Intense Unrest
Hazardous eruption is possible within days
Extension of the danger zone to 8 kilometers or more in the sector where the crater rim is low will be recommended.
Alert level 5 – Hazardous Eruption Ongoing
Pyroclastic flows may sweep down along gulfs and channels especially along those fronting the low part of the crater rim.
Additional danger areas may be identified as the eruption progresses. Danger to aircraft by way of ash cloud encounter, depending on the height of the eruption column and/or wind drift.
Source: Philippine Institute of Volcano and Seismology