The eruption spewed ash 19,700 feet into the sky.
Scientists have not yet determined whether the eruption was directly triggered by the earthquake in central Sulawesi on Friday. However, Indonesian news portal Tempo cited a government volcanologist who suspected it was.
Indonesia has many actives volcanoes. It is also located in the so-called Ring of Fire, one of the most active areas for earthquakes in the world.
President Donald Trump called Indonesian President Joko "Jokowi" Widodo on Tuesday to offer assistance with both the emergency phase and reconstruction from the earthquake and tsunami that struck Sulawesi.
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In addition to the growing death toll, hundreds of people were severely injured in Friday's disasters. With many roads blocked and key communication lines and infrastructure destroyed, food, water, fuel and medicine are struggling to reach the hardest-hit areas outside Palu, the largest city heavily damaged. More than 60,000 people have been displaced, according to the National Disaster Mitigation Agency.