Besides the 19 volcanoes, three others -- the Lokon and Karangetang in North Sulawesi and the Rokatenda in East Nusa Tenggara -- already have been on the high alert status since last year, the Jakarta Post reported.
Meanwhile, search teams looking for victims of the Mount Sinabung eruption had to halt their dangerous mission because of unsafe conditions, CNN reported.
The volcano in North Sumatra, which had been erupting sporadically since September, threw up super hot ash more than a mile into the sky over the weekend. The ash descended on the village of Sukameriah near the crater and at least 15 people in the area have been reported killed.
Three others were severely injured by the pyroclastic clouds emitted by Sinabung, the Post said. The report said 15 other villages had to be evacuated following the eruption.
The newspaper said the National Disaster Mitigation Agency, while raising the status of the 19 volcanoes across the country, did not issue any evacuation calls around them. The volcanoes are among the more the 125 active ones in the country.
"Volcanoes erupt in stages, they won't suddenly erupt," one agency expert said. "Their activity can be categorized from normal to waspada [alert] to siaga [high alert] to awas [danger, the highest level]."
Indonesia is among the world's most seismically active countries, situated on the Pacific Ring of Fire, an arc of volcanoes and fault lines encircling the Pacific Basin.
CNN said search and rescue teams around Sinabung have been conducting their operations around a 2-mile radius of the volcano. All of the dead and the injured were found in Sukameriah village, authorities said.
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