Mayon’s frequent rumbling, plumes worry Albay folk
LEGAZPI CITY—The continuous loud rumbling noises created by the “ashing,” or ejection, of short and dark plumes of ash and the frequency of volcanic earthquakes have made residents living around Mayon Volcano anxious, triggering fears of a hazardous eruption.
Jan-Rhea Grageda, 36, said every time they would hear the rumbling, which they likened to thunder, they would go out of their houses in Barangay Salugan in Camalig town to check on the volcano from afar.
She said the disturbing sound started on Tuesday night, but even then, their family was alert to a possible evacuation as their house was inside the 7-kilometer radius extended danger zone of the volcano.
“[The sound] was really alarming because every time we hear something like that, we know that anytime soon, there’s a possibility of a big eruption, just like before,” Grageda said in an online chat message on Wednesday.
Raziel Nace, 46, said the series of rumbling sounds was also loud enough to be heard in their area in Barangay Gapo, around 9 km to 10 km away from the volcano.
“We repeatedly heard it last night, and it was clearly heard even though our village is far from the volcano,” she said in a separate private message.
Tim Lawrence Florece, information officer of Camalig town, said residents inside the 7-km to 8-km extended danger zones of the volcano had been advised to “be calm and stay alert. “
“If alert level 4 is raised, residents in the villages of Salugan and Cabagñan will also be evacuated,” Florece told the Inquirer.
The provincial government on June 9 ordered the mandatory evacuation of residents living within the 6-km radius of Mayon, a day after the Philippine Institute of Volcanology and Seismology (Phivolcs) raised the alert level to 3 over the volcano. With alert level 3 raised, the public is warned that Mayon is likely to cause a hazardous eruption within weeks or even days.
In a bulletin on Wednesday, Phivolcs said about 304 weak and shallow low-frequency volcanic earthquakes (LFVQs) were recorded and associated with “discrete and rapid releases of volcanic gas” from the summit crater.
At least 761 LFVQs were recorded by the Mayon Volcano Network from July 16 to July 19, Phivolcs said.
“Some of these degassing events were accompanied by audible thunder-like sounds and entrained ash at the crater to produce ashing of short, dark plumes that drifted southwest,” Phivolcs said.
Paul Karson Alanis, resident volcanologist of Phivolcs Legazpi, said they recorded a total of 30 “ashing” events lasting 20 to 40 seconds and plume heights of 150 to 300 meters from 5:33 p.m. on Tuesday to 4:34 a.m. on Wednesday.
He said the volcanic earthquakes sometimes produced ashing with thunder-like sounds, which was reportedly heard in Legazpi City and Camalig town.
“The gas bubbles ascending from inside the volcano sometimes produce ash, and make sulfur dioxide emissions high,” Alanis said in a phone interview on Wednesday.
He said this could trigger ashfall in the southeast of the volcano facing the towns of Camalig, Daraga and Guinobatan.
“[The height of the plume] was still short, and the ash was likely washed out because of the rain,” he added.
Alanis said that since Monday, a new direction of lava flow had been noted at the Basud gully in Sto. Domingo town, which reached 600 meters.
“We cannot really tell if the lava flow became voluminous; it’s possible that the Bonga gully was already full and the flow was redirected to the lower crater lip in Basud,” Alanis said.
Based on the latest bulletin, the slow effusion of lava from the summit crater also continued to feed and bulk up about 2.8 km in the Mi-isi gully in Daraga and 2.4 km in the Bonga gully in Legazpi.
The collapsed debris had been deposited 4 km from the crater along the Basud channel.
The agency also recorded three pyroclastic density currents (hot, fast-moving mixture of gas, ash and rock debris) and 137 rockfall events from the volcano, which was lower than the past monitoring, Alanis said.