The sound of the eruption was heard in many parts of the world. As far away as the US!On Saturday, January15, the underwater volcano at Tonga erupted, about 65km north of the capital Nuku'alofa, triggering a tsunami that flooded Pacific coastlines from Japan to the US. It caused waves higher than a metre to crash into Tonga. Detailed information about its impact on Tonga is yet to emerge as communication remains cut off.GOES satellite imagery captured the eruption of the underwater volcano early Saturday morning.Tongans living overseas are facing an anxious wait for news of loved ones as the eruption cut the internet to Tonga. Even government websites and other official sources remained without any updates. According to the Tonga Geological Services, the plumes of gas, smoke and ash pouring from the volcano reached 20km into the sky. About 100,000 Tongans living in the 170 scattered islands are advised to drink bottled water and wear masks, as the dust from the volcano could contaminate water supplies.The shockwave generated by the massive volcanic eruption in Tonga was felt in many parts of the globe. In India, it was recorded in Chennai, which is located 12,000 km away from Tonga.Down to Earth is Science and Environment fortnightly published by the Society for Environmental Communication, New Delhi. We publish news and analysis on issues that deal with sustainable development, which we scan through the eyes of science and environment.