VOLCANIC ACTIVITY REPORT: KANLAON VOLCANO, NEGROS ISLAND
04 June 2024
1) Summary of Activity:
The Alert Level 2 (Increased or Moderate Level of Volcanic Unrest) was raised at at 8:00 PM of 3 June 2024 after a moderately explosive eruption occurred at the summit crater at 6:51 PM earlier in the evening. The event was recorded as an E-type earthquake that lasted six (6) minutes based on seismic data and produced a five (5) kilometer-high voluminous eruption plume. All ten (10) seismic stations, three (3) infrasound stations and two (2) visual monitors of the Kanlaon Volcano Network (KVN) recorded the explosion. Thermal camera monitors showed material collapsing from the incandescent plume forming pyroclastic density currents or PDCs that descended the southern slopes to a distance of two (2) to three (3) kilometers. Incandescent ballistic ejecta were also observed to rain down from the eruption plume. Rumbling sounds generated by the eruption were heard in La Castellana and La Carlota City, Negros Occidental and Canlaon City, Negros Oriental. Coarse ashfall reportedly fell upon barangays of these same areas and Bago City, Negros Occidental. Sulfurous odors were also experienced by residents in these areas as well as in Kanlaon Volcano Observatory-La Carlota City (KVO-LCC) and as far away as Murcia, Negros Occidental and Bacolod City. Below is the list of barangays that reported observations to KVO-LCC.
The 6:51 PM explosive eruption was preceded at 6:47 PM by a ML3.5 volcano-tectonic or VT event at a depth of approximately 10 kilometers some two (2) kilometers north of the summit crater. VT earthquakes are associated with rock-fracturing that can be induced by thermal or pressure-related stresses with the volcanic edifice. Kanlaon has been exhibiting periodic swarms of VT earthquakes since Alert Level 1 was raised in March 2020. Since 2023 alone, five (5) advisories on increased seismic activity have been released, the latest of which was last 26 May 2024. In addition, volcanic SO2 gas emission has been unsteadily increasing since May 2023 and has averaged 1,273 tonnes/day this year, substantially above the background emission of <300 tonnes/day. Lastly, real-time ground deformation monitoring indicates that the Kanlaon edifice has been undergoing a long-term very slow-rate swelling or inflation since March 2022 based on GPS parameters and a short-term inflation since April to July 2023 based on electronic tilt parameters.
Explosive activity at Kanlaon on 3 June 2024 was immediately succeeded by profuse degassing from the summit crater that waned by 8:20 AM on 4 June 2024 based on camera monitors. Post-eruptive degassing likely entrained volcanic ash that fell as light ashfall on the southwest sector of the volcano as reported by a KVO-LCC survey team. As of 12:00NN today, 04 June, a total of 84 weak low-frequency volcanic earthquakes events have been recorded by the KVN, consistent with current low-level degassing from the Kanlaon crater. SO2 emission measured by campaign survey today has reached 4,113 tonnes/day, the highest flux this year and the second highest ever measured from Kanlaon.
2) Current Outlook:
Kanlaon occasionally exhibits phreatic and short-lived explosive eruptions that produce small-magnitude hazards. Of the 43 eruptions recorded since 1866 including this most recent one, only the 1902 eruption was magmatic and associated with the generation of small-volume lava flows on the upper slopes. Current activity may evolve into the following scenarios:
a) If monitoring parameters are sustained, phreatic and short-lived explosive eruptions may subsequently occur and produce small-magnitude hazards that will endanger areas within the Four (4) Kilometer Permanent Danger Zone (PDZ). Unrest is likely caused by hydrothermal processes driven by magmatic degassing deep within the volcanic edifice. Alert Level 2 will be maintained until such time that monitoring parameters significantly change.
b) If seismic, ground deformation and volcanic gas parameters worsen, magmatic eruption may become likely. Current unrest is likely being driven by stresses within the volcanic edifice produced by rising magma. Eruptive activity could generate volcanic hazards that will endanger areas within the lava flow and PDC hazard zones delineated by DOST-PHIVOLCS. Alert Level 3 will be raised.
c) If monitoring parameters decline, unrest is driven by very shallow hydrothermal processes. Alert Level will step down to Alert Level 1 after sufficient observation has elapsed.
3) Recommendations:
Strict prohibition from the Four-Kilometer Radius PDZ is recommended at Alert Level 2. Barangays with areas within Kanlaon’s PDZ are: Ara-al and Yubo, La Carlota City; Sag-ang, Mansalanao, Cabagnaan and Biaknabato, La Castellana; Minoyan, Murcia; Masolog, Pula and Lumapao, Canlaon City and; Codcod, San Carlos City.
Local government units, disaster officials and the general public are urged to heed avoidance of the PDZ, as the chances of similar explosive eruptions occurring are significant, thus increasing the threat of volcanic hazards such as PDCs and ballistic projectiles within the PDZ.
Civil aviation officials should also warn aircraft from flying close to the volcano’s summit as sudden explosions can generate ash and rock fragments that can damage aircraft.
For the latest information on Kanlaon Volcano, please download the VolcanoPH Info app from the Google Play Store and refer to these DOST-PHIVOLCS official accounts:
DOST-PHIVOLCS
