With the Muslim holy month of Ramadan coming to an end, thousands of Muslims who were trying to travel home for the Muslim Eid festival are stranded in Indonesia because of a series of volcanic eruptions.

Officials concerned about safety for aircraft shut down four small airports on Java, the nation’s most populous island after the latest eruption by Mount Raung.  The same volcano last week shut down airports in the region including Bali’s Denpasar International. Volcanic ash is a concern for aircraft not because of visibility but because the ash turned into a form of molten glass when sucked into a jet engine.

The government has raised the alert level for Mount Raung to the second-highest level because of the hot ash and lava shooting from the mountain.

Then Mount Gamalama erupted on the nation’s North Maluku island shutting down Sultan Babullah International airport in Ternate.

Indonesia lies on the Pacific Ring of Fire.