MANILA, March 29 (Xinhua) -- Philippine authorities Thursday lowered the alert status of Mayon volcano from alert level 3 to alert level 2, signifying that the country's most active volcano has shown "a general decline in unrest."
The Philippine Institute of Volcanology and Seismology (Phivolcs) said it has observed "the cessation of eruptive activity and the decline to a moderate level of unrest" during the past two weeks.
However, the institute warned that the lowering of the alert status "should not be interpreted to mean that the volcano's unrest has ceased, considering that the edifice is still inflated relative to its baseline level."
"If there is a resurgence of volcanic unrest based on any one or combination of the above monitoring parameters, the alert status may step up to alert level 3 again," the institute said in its latest bulletin.
Philippine authorities lowered the alert status of Mayon volcano on March 6 from alert level 4 to alert level 3, meaning that the volcano has shown "decreased tendency towards hazardous eruption."
The alert level system used by Phivolcs runs from the lowest alert level 0 to the highest alert level 5.
Alert level 3 means decreased tendency towards a hazardous eruption and Alert level 2 means a moderate level of unrest, according to the Phivolcs.
The institute warned the public anew to avoid entering the 6-km permanent danger zone (PDZ) "due to perennial hazards of rockfalls, avalanche, ash puffs and sudden steam-driven or phreatic eruptions at the summit area."
"Furthermore, people living in valleys and active river channels are cautioned to remain vigilant against sediment-laden stream flows and lahars in the event of prolonged and heavy rainfall," the institute said.
For the past two weeks, the institute said it has observed the seismic activity has waned from a peak of 82 to less than 10 rockfall events.
Mayon volcano, the Philippines' most active volcano, rumbled back to life on Jan. 13 with lava fragments rising to its crater in a gentle eruption that prompted the authorities to evacuate thousands of villagers.
Following the lowering of Mayon volcano's status to alert level 2, the Philippine National Disaster Risk Reduction and Management said around 6,400 local evacuees who live near the volcano are expected to return home on Thursday.
Mayon volcano, which has an elevation of 2.46 km and a base diameter of 20 km, is located in Albay province approximately 300 km southeast of Manila on the island of Luzon.
The volcano is a popular tourist destination in the Philippines. It is famous for its near-perfect cone but has a long history of deadly eruptions. It has erupted 51 times during the last 400 years.
In an 1814 eruption, more than 1,200 people were killed and three towns were buried under mud and rock.
The Philippine archipelago straddles the Pacific "Ring of Fire" and is prone to earthquakes and volcanic eruptions.