MANILA, Philippines (AP) _ Scientists issued a preliminary alert as magma bubbled up inside the Mayon volcano Wednesday, less than a year after it erupted and drove 68,000 people from their homes in the southern Philippines.

Lava piles at the crater pit, increased volcanic ash and rising magma are a repeat of the conditions that came before Mayon spewed lava, belched red-hot boulders and blanketed towns with heavy ash last February.

Julio Sabit, of the Philippine Institute of Volcanology and Seismology, said the alert level does not yet warrant evacuation, but that could easily change.

``Something unusual has been happening at Mayon,'' Sabit said. ``Seismicity increased very rapidly so far this month, and the amount of volcanic ash has significantly increased.''

The 8,118-foot mountain, some 215 miles southeast of Manila, erupted Feb. 24 and forced evacuation of area villages and farms from Mayon's fertile slopes. Mayon's most violent eruption, in 1814, killed more than 1,200 people and buried an entire town in volcanic mud.