Wednesday, January 24, 2018

INTENSE BUT SPORADIC LAVA FOUNTAINING OCCURRED AT MAYON REACHING 500 TO 600 METERS HIGH



LEGAZPI CITY (Jan 24) - Alert Level 4 remains in effect over Mayon Volcano. The public is strongly advised to be vigilant and desist from entering the eight (8) kilometer-radius danger zone, and to be additionally vigilant against pyroclastic density currents, lahars and sediment-laden streamflows along channels draining the edifice.

In the latest bulletin issued by the Philippine Institute of Volcanology and Seismology (PHIVOLCS) at 8:00AM Wednesday, a total of five (5) tremor events corresponding to lava fountaining episodes, three (3) episodes of pyroclastic density current or PDC generation from lava collapse, and numerous rockfall events were recorded by Mayon's seismic monitoring network.

Rockfall events were generated by the collapsing lava front and margins of the advancing lava flow on the Miisi Gully and by shedding from the summit dome onto the Bonga Gully. Currently, the Miisi and Buyuan lava flows have advanced to three (3) kilometers and one (1) kilometer, respectively, from the summit crater.

Sulfur dioxide gas emission was measured at an average of 2466 tonnes/day on 23 January 2018. Electronic tilt and continuous GPS measurements indicate a sustained swelling or inflation of the edifice since November and October 2017, consistent with pressurization by magmatic intrusion.

Between 08:54 AM yesterday to 03:57 AM this morning, five (5) episodes of intense but sporadic lava fountaining from the summit crater lasting seven (7) minutes to one (1) hour and twenty (24) minutes occurred. The lava fountains reached 500 meters to 600 meters high and generated ash plumes that reached 3 kilometers to 5 kilometers above the crater. The events fed lava flows on the Miisi and Bonga Gullies, sprayed near-vent lava spatter, and fed incandescent rockfall on the summit area. Pyroclastic density currents or PDCs on gullies heading the Miisi, Lidong/Basud, and Buyuan Channels were also observed. The runout of PDCs on the Buyuan Channel is now exceeding 5 kilometers from the summit crater. (Mar de la Cruz)

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