Mayon Volcano's sulfur dioxide emission rate increases

State volcanologists on Monday observed a nearly 350-ton increase in the sulfur dioxide emission rate of Mayon Volcano in Albay province in the Bicol region. In its latest update, the Philppine Institute of Volcanology and Seismology (Phivolcs) said that the volcano emitted 853 tons of SO2 in the past 24 hours. Phivolcs recorded only 505 tons last October 10; 761 tons last October 8, and 350 tons last October 7. While the volcano’s steaming activity remained moderate and while the crater glow remained obscure, Phivolcs said that they detected seven volcanic earthquakes during the past 24 hours – bringing to 43 the number of volcanic earthquakes recorded from October 5 to 11. Mayon Volcano’s status, however, remained at Alert Level 2, which is characterized as "a state of unrest which could lead to more ash explosion or eventually to hazardous magmatic eruption." Phivolcs said the 6-kilometer radius Permanent Danger Zone (PDZ) around the volcano and the 7-km Extended Danger Zone (EDZ) on the southeast flank are off-limits due to the threat of sudden explosions and rock falls from the upper slope. "Active river channels and those areas perennially identified as lahar prone in the southeast sector should also be avoided especially during bad weather condition or when there is heavy and prolonged rainfall," Phivolcs added. Last July 10, the agency raised the alert at Mayon from Level 1 to Level 2 after noting a “moderate unrest." Alert Level 1 means there is low-level unrest with slight increase in seismicity. There is also a "slight increase in sulfur dioxide gas output above the background level. A very faint glow at the crater may occur, but no conclusive evidence of magma ascent." At this level, no eruption is imminent, Phivolcs said. Eruptions Phivolcs’ website on Mayon eruptions said the volcano has had at least 40 eruptions since February 1616. The most destructive eruption occurred Feb. 1, 1814, when pyroclastic flows, volcanic lightning, and lahar affected Camalig, Cagsawa, Budiao, Guinobatan and half of Albay. At least 1,200 were listed as casualties. The second most destructive eruption was from June 4 to July 23, 1897, as pyroclastic flow, lava flow, lahar and volcanic lightning caused 350 casualties. On July 20-24, 1766, pyroclastic and lava flows destroyed Malinao and damaged Cagsawa, Guinobatan, Budiao, Polangui and Ligao. There were 39 casualties. On July 7, 1853, 34 casualties were listed as ashfall and pyroclastic flow and lahar affected Camalig, Guinobatan, Ligao, Oas, Polangui, Malilipot, Bacacay, and Cagsawa. From Feb. 2 to April 4, 1993, pyroclastic and lava flow killed 77 and injured five. Mayon erupted again from July to October 2006. In August 2006, government ordered the evacuation of people living near the volcano. On Oct. 3, 2006, Phivolcs downgraded the threat level to Alert Level 2. On Oct. 25, it downgraded the threat level to Alert Level 1. But on Nov. 30 that year, Typhoon Durian caused mudslides of volcanic ash and boulders from the slopes of Mayon Volcano, burying at least 1,000. - GMANews.TV