Mount Raung on the main island of Java blasted ash and debris up to 2,000 meters (6,560 feet) into the air after rumbling for several weeks. Gamalama mountain in eastern Indonesia erupted on Thursday after months of quiet.

Transport Ministry spokesman Julius Adravida Barata said volcanic ash spewing from Mount Raung blew close to the East Java cities of Surabaya and Malang, forcing the Juanda International and Abdurrahman Saleh airports to close.

The Ministry said Sultan Babullah airport in Ternate, North Maluku’s province capital, was closed after Gamalama sent volcanic ash as high as 1,500 meters (4,920 feet) into the sky. Ash is hazardous to jet engines.