Jakarta, April 11 : The Indonesian Anak Krakatau volcano erupted expelling ash and plumes of smoke that travelled more than 500 metres high, local authorities report on Saturday. The Center for Volcanology and Geological Disaster Mitigation (PVMBG) said the volcano, one of the country's most active, erupted twice on Friday night for a total of 40 minutes, reports Efe news. "PVMBG monitoring shows that the eruption continued until Saturday morning at 5:44 WIB ," Agus Wibowo, head of the National Disaster Mitigation Agency (BNPB) said in a statement on Saturday. Authorities said they were closely monitoring the volcano which is located on an uninhabited island in the Sunda Strait. On December 22 2018, a strong eruption caused a landslide that triggered a tsunami killing hundreds of people who were spending the Christmas holidays on the coasts of Java and Sumatra. At least 439 people died and more than 7,200 were injured, according to official figures. As a result of that eruption, the Anak Krakatau, which now rises just over 110 metres above sea level, lost around 200 meters in height. Discovered in 1927, the Anak Krakatau emerged from the waters more than half a century after the 1883 eruption of Krakatoa. It has continued to grow ever since. Krakatau's caldera, a cauldron-like hollow that forms shortly after an eruption, was destroyed in 1883 after a series of massive blasts that killed over 36,000 people and which caused several tsunamis. The effects of the monumental explosions were felt around the world for weeks. Indonesia sits on the Pacific Ring of Fire, an area of great seismic and volcanic activity that is shaken yearly by some 7,000 tremors, most of them moderate. /IANS