Warning signs
GPS signals could offer a new and more effective method for detecting tsunamis than current warning systems. Tsunamis are formed when sudden movement on the seabed, caused by earthquakes, landslides or volcanic eruptions, displaces the water above it. The initial wave is often only centimetres high, but it’s enough to cause a ripple in the Earth’s atmosphere as it pushes up air, creating an acoustic wave that is amplified as it travels high into the ionosphere, 300 kilometres above the surface of the Earth. This, in turn, affects radio signals sent by GPS satellites to receivers on the ground. Researchers from UCL and universities across Japan have developed a way to interpret the changes in these signals to gather critical information that may allow tsunami warnings to be issued earlier and predict second or third waves. Current warning systems are based on seismic activity, using sensors to detect changes in water pressure, and aren't very accurate.