Tagaytay, Philippines — Tens of thousands of people have evacuated towns in the Philippines left covered in heavy grey ash by the eruption of a volcano, and CBS News correspondent Ramy Inocencio says the government was planning Tuesday to evacuate hundreds of thousands more.

The Taal volcano sent a plume of ash, steam and rock six to nine miles into the sky with a violent explosion on Sunday, and on Tuesday it was still on alert level four of five. That means officials believe a "hazardous eruption" is imminent in the region, which is heavily farmed and popular for tourism.

Scientists warned that new fissures were appearing in the ground, and about 50 earthquakes jolted the area in just eight hours on Tuesday, all signs that another, possibly larger eruption was coming.

Taal has been spewing fountains of red hot lava half a mile high, sparking its own spectacular lightning storms and turning green, tropical vistas grey with ash.

Many families who live near the volcano have fled to evacuation centers to wait out the disaster.

Inocencio says the volcano is also bringing health concerns. People have been advised to wear masks to protect from the ash, but supplies of the face coverings were running out, even in the capital of Manila. The sprawling capital city is only about 50 miles north of the volcano.