The night sky above Hawaii’s largest island glowed bright red yesterday as the world’s largest active volcano erupted for the first time in nearly 4 decades. Lava was seen flowing down the side of the Mauna Loa, but as it’s contained within the volcano’s summit at 4,169 metres above sea level, authorities say it doesn’t pose a threat to residents living downslope – for now. However, Big Island’s 200,000 inhabitants have been told to make preparations to evacuate just in case, as the volcano’s last eruption in 1984 sent a flow of lava within 8km of Hilo, the island’s largest city. Officials warn the air quality could deteriorate in the coming days due to high levels of volcanic gases, including sulphur dioxide, that can be released in eruptions. People heading outside have been urged to cut back on “strenuous exercise” and wear a mask to avoid inhaling ash particles.