Researchers at the University of California, San Diego have found a hidden soft layer beneath Greenland's ice sheet. This layer can let ice move faster toward the sea. The study used seismic waves from earthquakes to map what lies under the ice. By measuring how fast these waves travel, scientists told if the ice sits on hard bedrock or soft sediments. Soft sediments can change shape and act like a lubricant, making ice slide easily. Geophysicist Yan Yang led the study published in the journal Geology. "The safety of coastal communities depends on accurate forecasts," Yang said. "Knowing whether the bed is hard rock or soft sediment is essential for improving future sea-level change predictions." The research challenges old ideas that only surface melting causes ice loss. Instead, conditions below the ice play a big role. When meltwater seeps down through shafts called moulins, it reaches the soft sediment and lowers friction. This speeds up glacier flow to the coast. Satellite data shows Greenland's ice sheet raised sea levels by about 1.1 cm from 1992 to 2018. The findings warn that future warming could speed this rise. Some parts of Greenland thought stable may not be. They show little surface change but have soft bases that could let ice move quickly once warmed. The study reveals a patchwork of soft and hard areas under the ice, making predictions complex. Current ice models often miss these basal details. Scientists hope combining seismic data with ice shape and movement maps will improve forecasts. While the study focuses on Greenland, its lessons may apply worldwide. Better mapping of ice bases is vital for planning against rising sea levels and climate impacts.