LEGAZPI CITY—Residents near Mayon were warned anew to be on high alert for possible lahar flows as the level of sulfur dioxide that the volcano was blowing off increased and rains were likely to bring down volcanic debris.

The Philippine Institute of Volcanology and Seismology (Phivolcs) kept the alert level at 2 but recommended that the 6-kilometer-radius permanent danger zone and the 7-km extended danger zone be kept strictly off limits.

Phivolcs started giving the recommendation three months ago when the alert level was raised to 2, which means a state of unrest that could lead to ash explosions or to hazardous eruption of magma.

Scientists manning the observatory center at Liñgon Hill in Daraga, Albay, recorded the first ash explosions of Mayon early morning of Sept. 15.

On Tuesday, Phivolcs said the sulfur dioxide emission soared anew to 838 tons during the past 24-hour monitoring period.

Resident volcanologist Eduardo Laguerta said previous records revealed the following trend: 430 tons per day on Sept. 20; 424 tons on Sept. 19; and 582 tons on Sept. 17.

The 24-hour seismic observation showed only four volcanic earthquakes compared to a total of 74 from Sept. 14 to Sept. 20.

Laguerta, however, said the crater glow was continuously obscured by thick clouds.

Phivolcs scientists are trying to find a way to take a closer look at the 200,000-cubic meter lava dome that could collapse anytime and may endanger the residents of Barangays Buyuan and Padang in Legazpi City.

“We have to be very vigilant, but all we could do is wait for the weather to clear up in order to conduct the survey for fresh photos of the lava dome,” he said.

Last week, Albay Gov. Joey Salceda and Cedric Daep, head of the Albay Public Safety and Emergency Management Office, told barangay disaster units to be on alert and to be extra vigilant even without a major eruption.