JAKARTA, Indonesia (AFP)—About 170,000 passengers were left stranded on Sunday as Indonesia shuttered its main international airport and seven others, cancelling hundreds of flights after Mount Anak Krakatoa spewed a plume of volcanic ash and lava from more than 150 kilometres away.

Mount Anak Krakatoa erupted on Saturday, producing a fountain of lava and booming sounds that could be heard up to a few hundred kilometres away, the geology agency said in a statement.

Two new eruptions were recorded on Sunday, the volcanology agency warned.

Ash from the volcano was detected in the airspace surrounding Soekarno-Hatta International Airport, prompting authorities to suspend operations, the ministry said.

The suspension was extended until 8:59 am Monday “due to increased eruptive activity at Mount Anak Krakatoa”, the airport authority said in an Instagram post.

Operations were also suspended at seven other airports until 8:59 am, authorities said on Instagram. These include the Husein Sastranegara airport in Bandung and Radin Inten II airport near Bandar Lampung on Sumatra, the ministry said.

“To date, 1,558 flights have been delayed at the eight affected airports, with 170,000 passengers stranded,” the ministry said in a statement on Sunday.

More than 900 affected flights were to and from the Soekarno-Hatta International Airport, it added.

Several airports in cities including Semarang and Surabaya have been prepared as alternatives for landing, Transportation Minister Dudy Purwagandhi said.

– Passengers scrambling –

The disruption left some passengers scrambling to find alternative flights.

Henny Yensan, 44, who had hoped to go back to her hometown with her mother, said “everybody was disappointed”.

“No one flew into a rage because, after all, this is due to natural disaster,” the businesswoman who had to reschedule her flight to Tuesday told AFP.

Samuel Guiberteau, a Danone executive on a business trip to Lombok since Friday, said “nothing is certain for the moment”, as he searched for alternative flights back to the capital.

“I had found another flight on Citilink, but it was also cancelled,” the 47-year-old told AFP by phone, adding that he had no alternative but to stay in Lombok for the time being.

Volcanic ash also reached the city of Bandar Lampung in the southern tip of Sumatra, blanketing parked cars and roadsides.

“I’m worried it could seriously affect the lungs and cause a lung infection,” Andre Bayu Saputra, 25, told AFP on Sunday.

Schools across Jakarta will be closed on Monday as classes move online, the city said in a statement, without specifying how long the measure will be in place.

– Hazard warning –

Anak Krakatoa, which means Child of Krakatoa, sits in a strait that separates the islands of Java and Sumatra.

Ships passing through the strait were asked to increase vigilance for possible disruption to navigation safety due to volcanic activities.

Vessels are prohibited from approaching an exclusion zone of three kilometres radius from the volcano, local port authorities said in a statement.

The volcano has been sporadically active since it emerged from the sea at the beginning of last century in the caldera that formed after the 1883 eruption of Mount Krakatoa.

That disaster was one of the deadliest and most destructive in history with an estimated 35,000 people killed.

Geology agency head Lana Saria said “seismic activity indicates the movement or release of volcanic fluids within the volcanic system”.

“However, the timing, magnitude, and nature of the next eruption cannot be precisely predicted,” Lana added.

Lana warned against approaching Anak Krakatoa, saying materials ejected from the volcano could endanger those within the exclusion zone.

She said the most recent series of eruptions do not have the potential to trigger a tsunami at this time.

A 2018 tsunami triggered by a collapse of parts of Anak Krakatoa killed 429 people and left thousands displaced.

Indonesia, a Southeast Asian archipelago nation, sits on the Pacific Ring of Fire, where the meeting of continental plates causes high volcanic and seismic activity.