A ship rests on land after it was swept ashore during Friday's tsunami at a neighbourhood in Donggala, Central Sulawesi, Indonesia. Picture: Tatan Syuflana/AP

Jakarta, Indonesia - A volcano erupted Wednesday morning on the same central Indonesian island as an earlier earthquake and authorities warned planes about volcanic ash in the air.

Mount Soputan in North Sulawesi province spewed ash 6,000 meters (19,700 feet) into the sky Wednesday morning. No evacuations were immediately ordered.

A government volcanologist suspects the eruption was triggered by the 7.5 magnitude earthquake in Central Sulawesi on Friday.

"It could be that this earthquake triggered the eruption, but the direct correlation has yet to be seen as there had been an increase in the Mount Soputan activity," the volcanologist, Kasbani, told online news portal Tempo.

Kasbani, who uses one name and leads the Vulcanology and Geology Disaster Mitigation agency, said volcanic activity had been increasing at Soputan since August and began surging Monday. "It is possible that the quake accelerates (the eruption)," he added.

Soputan's eruption status was raised from an alert to standby 4 kilometres (2.5 miles) from the summit and up to 6.5 kilometres to the west-southwest. Standby status means the public should avoid the area nearest the volcano and have masks available in the event of ashfall.

Planes were warned of the ash clouds because volcanic ash is hazardous for plane engines.

The earthquake in Central Sulawesi set off a tsunami and has devastated several communities.

Indonesia, an archipelago of more than 250 million people, sits on the Pacific "Ring of Fire" and is prone to earthquakes and volcanic eruptions. Government seismologists monitor more than 120 active volcanoes.

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AP