The mountain, located 150 miles southeast of Manila, has shown increasing unrest in recent weeks.
Officials warn that up to 80,000 residents in 70 villages could be affected if Bulusan’s activity increases further.
One of the mountain’s strongest blasts so far sent ash soaring more than a mile above the central Philippines.
Ash plumes emitted by Bulusan during May 2007 forced residents to wear face masks to avoid breathing volcanic debris.
In late 2006, the volcano belched ash that blanketed several villages.
Bulusan is one of the Philippines’ most active volcanoes, erupting 15 times since 1866.
It usually produces sudden steam-driven explosions that send ash soaring above the crater.