Tsunamis are giant, powerful waves most often caused by earthquakes beneath the ocean floor. Their incredible power can destroy entire communities, then drag the debris out to sea. This video shows what causes tsunamis and the importance of evacuating any area under a tsunami alert. | National Geographic TV

Researchers say a 50-metre tsunami lifted a 1,200-tonne boulder inland in Tonga some 7,000 years ago, revealing the long history of tsunamis in the region. The discovery, found on the southern side of Tongatapu, is believed to be one of the largest wave-transported rocks in the world 🌍, offering new insights into the Pacific’s geological past and ongoing tsunami risks. | ABC Pacific