Researchers have for the first time detected temporary changes in Earth's gravitational field just before an earthquake.
Jean-Paul Montagner at the CNRS Institute of Earth Physics in Paris and his team analysed gravimetric and seismic data recorded during the massive 2011 Tohoku earthquake in Japan. They detected a signal that exceeded the background seismic noise and whose amplitude was consistent with that predicted by theoretical models. The signal occurred several seconds before seismic waves arrived.
Developing sensors to detect such transient gravity signals could lead to new early-warning systems for tsunamis and other earthquake hazards, the authors say.