MANGGIS, Indonesia — Wayan Suta Negara makes his living mining sand on Mount Agung, the largest mountain on the Indonesian island of Bali. He was born on the slope of the sacred volcano but was forced to leave his home recently when fears of an eruption led to a mass evacuation.

For the past two months, his life has been filled with uncertainty as he waits to see if the mountain erupts in the same spectacular manner it did in 1963. The volcano, which vented huge plumes of ash and smoke earlier this week, could experience a major eruption at any time, officials said on Friday.

Mr. Negara, 26, and his family have fled their home and taken shelter in an empty market stall in the village of Manggis, where the authorities have set up an evacuation center.

Every few days, he returns to his village, an hour away by motorcycle, to feed his dog and chickens. While he is there, he prays for the safety of his home and for his ancestors’ spirits, who according to local belief still reside there.