Phivolcs lowers Mayon alert level to 2

After weeks of relative calm, state volcanologists lowered the alert level of restive Mayon Volcano in Bicol to "2" Wednesday morning. But the Philippine Institute of Volcanology and Seismology (Phivolcs) warned residents against being complacent as the unrest of the volcano has not ceased. "This means a further reduction in the likelihood of hazardous eruption. However, the lowering of the alert level from 3 to 2 should not be interpreted that the unrest of the volcano has ceased. If there is resurgence in the volcano’s activity, the alert level may be raised back to 3 but if there is noticeable downward trend in the monitored parameters, then the alert will be lowered to Alert Level 1," it said in its 7 a.m. bulletin. Alert Level 2 means moderate unrest, with low to moderate level of seismic activity and episodes of harmonic tremor and increasing sulfur dioxide flux. There is faint or intermittent crater glow and swelling of edifice may be detected. Under Alert Level 2, the 6-km radius Danger Zone may be extended to 7 km in the sector where the crater rim is low.

See the complete table on the Phivolcs website.

Last Dec. 14, Phivolcs raised the alert level to "3" after noting heightened activity there. It raised the alert level to "4" last Dec. 20. The raising of the alert level last Dec. 14 prompted Albay's provincial authorities to evacuate some 47,000 residents in the volcano's danger zone. But with the lowering of the alert level to "3" last Jan. 2, most of the residents were allowed to go home. Phivolcs said that in lowering the alert level to "2," it cited: * Lower seismic activity, with 6 volcanic earthquakes in the last 24 hours. For the past two weeks, majority of the type of recorded earthquakes were related to rockfalls and rolling down of lava fragments at the volcano’s upper slopes. "The lack of remarkable seismic events, such as harmonic tremors, suggests no active transport of magma to shallow levels," it said. * Ground Deformation: Decrease in water discharge of springs at the lower slopes of Mayon Volcano as a result of the inflation of the volcano. Since Dec. 30, monitored springs have recovered and increased in discharge. These measurements indicate a return of the volcanic edifice to a deflated state, suggesting that no pressure build-up has taken place and reflect a general static condition of residual magma in the volcanic pipe and beneath the crater. * Gas Measurements: Sulfur Dioxide emission rate was measured Tuesday at an average of 597 tonnes/day (t/d). Measured levels have decreased considerably from a high of 2,621 t/d to a low of 597 t/d. * Visual Observation: No ash ejections were observed since December 29. Steam emission was most of the time weak to moderate and white in color indicating considerable decrease in energy. Crater glow remained visible to the naked eye at night possibly due to the still-hot residual magma beneath the crater. Phivolcs still recommended that the public should not enter the 6-km radius Permanent Danger Zone and the 7-km Extended Danger Zone on the southeast of the volcano due to continuing threat from sudden explosions, rockfalls from the upper slopes and pyroclastic flows due to sudden collapse of unstable lava deposits. "Active river channels and those perennially identified as lahar prone in the southern sector should also be avoided especially during bad weather conditions or when there is heavy and prolonged rainfall," it said. - RSJ, GMANews.TV