A volcano has erupted on the same central Indonesian island still reeling from last week's devastating earthquake and tsunami and authorities are warning planes about volcanic ash in the air.
Mount Soputan in North Sulawesi province spewed ash 6000 metres into the sky on 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.
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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 four kilometres from the summit and up to 6.5km 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.
