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FAST FACTS: Taal Volcano alert levels

Rappler.com
FAST FACTS: Taal Volcano alert levels
Taal Volcano, which has been put under Alert Level 4, shows signs that hazardous eruption is possible within days

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

  • All monitored parameters are within background levels
  • Volcano is quiet

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

Alert Level 1: Low level of volcanic unrest

  • Low-level seismicity, fumarolic (smoke), or other activity
  • Disturbance in magma, earth surface, and hydrothermal activities (magmatic sources associated with heated water in the volcanic area) 

No eruption is imminent. 

Alert Level 2: Increasing unrest

  • Low to moderate level of seismicity, persistence of local but unfelt earthquakes
  • Ground deformation measurements are above baseline levels
  • Increased water and/or temperatures of ground probe holes
  • Increased bubbling at Crater Lake

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

  • Relatively high unrest
  • Seismic swarms, including increasing occurence of low-frequency earthquakes and/or harmonic tremor
  • Sudden or increasing changes in temperature, bubbling activity, radon gas emission, or pH levels of Crater Lake
  • Bulging of the volcanic edifice and fissuring (cracks) may occur

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

  • Intense unrest
  • Continuing seismic swarms, including harmonic tremor and/or earthquakes which are usually felt

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

  • Base surges accompanied by eruption columns
  • Lava fountaining or lava flows

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

Read Rappler explainers on Taal Volcano: