A volcano in the eastern Philippines spewed a huge, dark cloud on Sunday, prompting evacuations from ash-covered towns while authorities warned of possible further eruptions.

The blast from Bulusan volcano in the rural Sorsogon province lasted about 17 minutes, sending a grey plume shooting up at least one kilometer, according to the Philippine Institute of Volcanology and Seismology. 

"There was a phreatic eruption of the Bulusan volcano, meaning the explosion was caused by the boiling water under the crater," institute head Renato Solidum told local radio DZBB.

In response, authorities raised the alert to one on the 5-level system, indicating "low-level unrest."

Residents near the valleys and rivers were also ordered to be vigilant for mud and stream flows in the event of heavy rainfall. 

Bulusan volcano has been active in recent years, with a dozen similar eruptions recorded in 2016 and 2017.

The Philippines is located in the seismically active Pacific "Ring of Fire" and has over 20 active volcanoes.