FAST FACTS: Taal Volcano alert levels

MANILA, Philippines – Taal Volcano in Batangas has been recording tremors as early as 11 am on Sunday, January 12. 

As of writing, government raised to Level 4 the alert for the volcano.

Here's what you should know about volcano alert levels for Taal, according to the Philippine Institute of Volcanology and Seismology (Phivolcs):

Alert Level 0: Quiet or no alert

At Alert Level 0, there is no eruption in the foreseeable future.

Alert Level 1: Low level of volcanic unrest

No eruption is imminent. 

Alert Level 2: Increasing unrest

Magmatic intrusion is probable, which may lead to an eruption. However, if trend shows a decline, alert may go down to Level 1.

Phivolcs raised Alert Level 2 for Taal Volcano at 2:30 pm on Sunday due to a phreatic explosion, a steam-driven episode that occurs when water beneath the ground is heated by magma, lava, hot rocks, or new volcanic deposits.

Alert Level 3: Magmatic unrest

The alert for Taal Volcano was raised to Level 3 at 4 pm. Volcanic tremors and earthquakes were felt in Volcano Island and in barangays of Agoncillo, Batangas. Ashfall was also present southwest of Taal.

At this level, Phivolcs "strongly recommended" the evacuation of Taal Volcano Island and high-risk barangays in Batangas due to possible hazards of pyroclastic density currents (flows of hot gas, ash, and rocks that rush down volcanic slopes) and volcanic tsunami.

Alert Level 4: Hazardous eruption imminent

At this level, hazardous eruption is possible within days.

The Civil Aviation Authority of the Philippines (CAAP) at this point is instructed to advise aircrafts to avoid airspace around Taal Volcano due to airborne ash and ballistic fragments that could cause hazards to an aircraft.

Phivolcs raised the alert to Level 4 at 7:30 pm. Two volcanic earthquakes of magnitudes 2.5 and 3.9 were felt at Intensity III in Tagaytay City and Alitagtag, Batangas, respectively.

CAAP said arriving flights were suspended beginning 7 pm Sunday, while departing flights were suspended 6:22 pm onwards. As of Monday morning, CAAP said they would continue to assess the situation. (READ: NAIA flights 'on hold' due to Taal Volcano ash eruption)

Alert Level 5: Hazardous eruption in progress

Eruptions at this final alert level pose extreme hazards to communities west of the volcano (such as Agoncillo) and ashfalls on downwind sectors. –

Read Rappler explainers on Taal Volcano: