PINATUBO VOLCANO BULLETIN

12 August 2021

08:00 A.M.

 

This serves as a notice for the lowering of the alert status of Pinatubo Volcano from Alert Level 1 (Low-level Unrest) to Alert Level 0 (Normal).

 

Since 1 July 2021, there has been a continued decline in earthquake activity and a return to baseline seismic parameters in Pinatubo Volcano. A total of 104 volcanic earthquakes or an average of 2-3 events/day having magnitudes of M_L0.8 to M_L1.3 was recorded by the Pinatubo Volcano Network from 1 July to 11 August 2021. This is a significant decrease compared to the period from 28 January to 30 June 2021 when earthquake activity averaged 12-13 events/day and ranged in strength from M_L 0.7 to M_L3.2. In addition, diffuse CO₂ flux from the Pinatubo Crater lake, which is an indication of deep magma degassing, was measured at 263 tonnes/day in mid-April 2021, well within the background range of <1000 tonnes/day recorded since 2008. Lastly, data from continuous GPS monitoring of the Pinatubo edifice that began in March 2021 indicate that ground deformation detected by InSAR data analysis for the period June 2020 to May 2021 is likely tectonic, rather than volcanic, in origin.

 

In view of the above, PHIVOLCS-DOST is now lowering the alert status of Pinatubo Volcano from Alert Level 1 to Alert Level 0.  This means observational parameters have returned to baseline levels and the volcano has returned to a period of quiescence. However, in the event of a renewed increase in any one or combination of the above monitoring parameters, the alert status may step up once again to Alert Level 1. Entry into the Pinatubo Crater area must always be conducted with caution due to the perennial hazards of rockfalls, landslides and lethal expulsions of volcanic CO₂. Furthermore, people living in valleys and active river channels are cautioned to remain vigilant against sediment-laden streamflows and lahars in the event of prolonged and heavy rainfall. DOST-PHIVOLCS is closely monitoring the volcano’s condition and any new development will be relayed to all concerned.

 

This will be the last bulletin for Pinatubo Volcano until new developments in monitoring parameters occur.

 

 

DOST-PHIVOLCS