A REMOTE volcano in Indonesia has erupted again, sending a tower of ash more than five kilometres into the sky.
Thousands were evacuated and an international airport was closed after Mount Ruang erupted several times on Tuesday.
The 725-metre-tall volcano had already erupted more than half a dozen times this month, forcing more than 6,000 people to flee their homes.
On Tuesday, the alert level was raised to its highest, the country's volcanology agency said.
Ruang, a stratovolcano, is one of the most active in the Ring of Fire region - a tectonic belt of volcanoes and earthquakes in the Pacific Ocean.
Located in Indonesia's North Sulawesi province, the volcano erupted about 1.15am local time and twice more on Tuesday morning.
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A six-kilometre exclusion zone was established as locals were urged to stay vigilant about "the potential for ejections of incandescent rocks, hot clouds and tsunamis due to eruption material entering the sea".
Dramatic photos and video showed a molten red stream burst into the sky as a large ash cloud spilled from the crater.
Burning embers are understood to have hit local houses.
More than 800 people live on the island of Ruang, most of whom were evacuated following the recent eruptions.
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Some of the evacuated residents had returned to their homes after the previous emergency response status ended on Monday, reports an AFP journalist.
It is not yet clear how many residents had returned to their homes and how many evacuated once again.
Sam Ratulangi International Airport in the provincial capital of Manado, more than 100 kilometres from the volcano, was forced to close again following the latest eruption.
A notice from state-run air traffic control provider AirNav Indonesia said the airport was shutting down due to "Ruang volcanic ash".
Indonesia is prone to experience frequent seismic and volcanic activity due to its position on the Pacific "Ring of Fire".
Mount Ruang erupted five times earlier this month, sparking a tsunami warning and a mass evacuation of more than 11,000 people.
Footage from the time showed the volcano spewing flames and red smoke into the sky which was racked by lightning storms.
There were fears that part of the volcano could collapses and spark a tsunami, as happened in 1871.
And in 2018, another volcano in Indonesia - Anak Krakatau - caused a tsunami that killed 430 after parts of the mountain fell into the ocean.
What is the Ring of Fire?
THE Ring of Fire is a belt of volcanoes and tectonic activity that surrounds most of the Pacific Ocean.
The horseshoe-shaped string stretches 40,000 km all the way from Asia to South America.
Earth's most dramatic and ferocious seismic events happen along the active ring where plenty of tectonic plates overlap.
The Ring of Fire is home to between 750 and 915 active or dormant volcanoes - roughly two thirds of the worlds total number.
Around 90% of the world's earthquakes also strike there.
Because so many different tectonic plates converge there, the interaction between them forms oceanic trenches, volcanic arcs, basins and volcanic belts.
It has existed for over 35 million years and even includes some older, extinct volcanoes.
Some of the world's most famous volcanoes, including Mount St Helens, Mount Pinatubo and Mount Ruiz are found there.