The philippines: The Philippines' most active volcano, Mayon, is showing signs of escalating activity, prompting authorities to reinforce exclusion zones and warn of potentially dangerous eruptions, the Philippine Institute of Volcanology and Seismology (Phivolcs) said Thursday.

According to Anadolu Agency - English, Phivolcs has prohibited entry into the six-kilometer (3.7-mile) Permanent Danger Zone around the volcano, and aircraft have been advised to avoid flying close to the summit. Nearly 50 pyroclastic flows, which are fast-moving currents of hot gas, ash, and volcanic debris, were recorded over a 24-hour period, the agency added.

Phivolcs Director Teresito Bacolcol warned of the deadly potential of such flows, recalling they killed 77 people during Mayon's 1993 eruption, according to the Philippine News Agency. Early Thursday, a dome-collapse event generated grayish ash plumes that rose about 1,000 meters (3,280 feet) above the crater before drifting northwest.

Phivolcs reported that thin ashfall has been observed in Legazpi City, Ligao City, Bacacay, Guinobatan, Camalig, and the barangays of Anislag and Busay in Daraga, Albay. Mayon's alert level was raised to Level 3 on Tuesday following hundreds of rockfall events recorded in less than a week, indicating increased unrest and the possibility of hazardous eruptions.

Authorities have also warned of additional threats, including lava flows, ballistic fragments, landslides, explosions, and fast-moving volcanic mudflows, especially during periods of heavy rainfall.