The Anak Krakatau erupted twice in just over an hour, spewing volcanic ash as high as 3,000 meters into the air, according to the country's Agency for Volcanology and Geology.
The volcano erupted at 07:46 (0046 GMT) local time on Friday and then struck again 62 minutes later. The 157-meter-high Anak Krakatau, located between the islands of Java and Sumatra, has erupted more than 10 times since March this year.
Authorities have issued the second highest alert level, according to Oktory Prambada, an official with the Agency for Volcanology and Geology. Prambada claimed that an evacuation order was not implemented, but tourists and residents were advised not to go near the volcano.
Indonesia sits on the Pacific "Ring of Fire" and has 127 active volcanoes. As of Friday, four Indonesian volcanoes were at the second-highest alert level, including Anak Krakatau, Merapi in Central Java, Semeru in East Java and Karangetang in North Sulawesi.
A December 2018 eruption of Anak Krakatoa triggered a landslide and triggered a tsunami in Banten, a province in West Java and Lampung province, killing at least 430 people.
