Journal Article

Prompt gravity signal induced by the 2011 Tohoku-Oki earthquake

Chassande-Mottin, Eric, Clévédé, Eric, Montagner, Jean-Paul, Bernard, Pascal, Ampuero, Jean Paul, Harms, Jan, Juhel, Kévin, Whiting, Bernard, Lognonné, Philippe, Barsuglia, Matteo

2016

Overview

Transient gravity changes are expected to occur at all distances during an earthquake rupture, even before the arrival of seismic waves. Here we report on the search of such a prompt gravity signal in data recorded by a superconducting gravimeter and broadband seismometers during the 2011 Mw 9.0 Tohoku-Oki earthquake. During the earthquake rupture, a signal exceeding the background noise is observed with a statistical significance higher than 99% and an amplitude of a fraction of μGal, consistent in sign and order of magnitude with theoretical predictions from a first-order model. While prompt gravity signal detection with state-of-the-art gravimeters and seismometers is challenged by background seismic noise, its robust detection with gravity gradiometers under development could open new directions in earthquake seismology, and overcome fundamental limitations of current earthquake early-warning systems imposed by the propagation speed of seismic waves. Earthquakes have been theorised to produce gravity signals that may arrive before seismic waves, but until now they had not been detected. Montagner et al . have detected prompt gravity signals from the 2011 Tohoku-Oki earthquake thus allowing an early warning of earthquakes before seismic wave arrival.

• Publisher: Nature Publishing Group UK,Nature Publishing Group,Nature Portfolio
• Subject: 639/766/930 / 704/2151/2809 / 704/4111 / 704/445/508 / Earth Sciences / Earthquakes / Emergency communications systems / Gravity / Humanities and Social Sciences / multidisciplinary / Observatories / Science / Science (multidisciplinary) / Sciences of the Universe / Seismic activity / Seismic waves / Seismology / Warning systems