MANILA >> A Philippine volcano spewed plumes of ash Tuesday, but volcanologists say the steam-driven explosions do not indicate an imminent violent eruption.

Mount Bulusan ejected ash up to .6 mile high for about 10 minutes and a smaller explosion hours later lasted a minute, Philippine Institute of Volcanology and Seismology director Renato Solidum said. There were no indications that the activity involved magma rising from below, he said.

The institute reminded local government units and the public that entering the 2.5 mile radius permanent danger zone is strictly prohibited. Pilots were advised to avoid flying close to the summit due to possible sudden ash explosions.

Bulusan, one of 23 active volcanoes in the Philippines, is about 240 miles southeast of Manila.

Solidum said he is not recommending further residential evacuations because most of the ash would fall on the upper slopes of the volcano. Settlements beyond 2.5 mile radius may receive trace amounts of ash and residents should cover their mouths with handkerchiefs or masks, he added.

Bulusan has not had a violent eruption since 1918. A 2011 explosion shot up an ash plume and prompted about 1,200 villagers to flee to shelters.

The country is in the Pacific “Ring of Fire,” where volcanic activity and earthquakes are common. In 1991, Mount Pinatubo in the northern Philippines exploded in one of the biggest eruptions in the 20th century.