The ash cloud above Mount Lewotobi Laki-laki on Monday was about four times taller than the one produced by an eruption there last month.

More frequent eruptions in recent months have led Indonesian authorities to raise the alert level and safety warnings for nearby villages.

Dozens of flights to and from Indonesia’s Bali island were cancelled Monday after a volcano belched a colossal ash tower 18 kilometers (11 miles) into the sky, authorities said. The aviation disruption came just weeks after the same rumbling volcano caused dozens of flight cancellations to and from the popular resort island.