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Science. 2017 Dec 1;358(6367):1164-1168. doi: 10.1126/science.aao0746.

Observations and modeling of the elastogravity signals preceding direct seismic waves.

Author information

1
Institut de Physique du Globe de Paris, Sorbonne Paris Cité, Université Paris Diderot, CNRS, France. vallee@ipgp.fr.
2
Seismological Laboratory, California Institute of Technology, Pasadena, CA, USA.
3
Institut de Physique du Globe de Paris, Sorbonne Paris Cité, Université Paris Diderot, CNRS, France.
4
AstroParticule et Cosmologie, Université Paris Diderot, CNRS/IN2P3, Commissariat à l'Energie Atomique et aux Energies Alternatives, Irfu, Observatoire de Paris, Sorbonne Paris Cité, France.

Abstract

After an earthquake, the earliest deformation signals are not expected to be carried by the fastest (P) elastic waves but by the speed-of-light changes of the gravitational field. However, these perturbations are weak and, so far, their detection has not been accurate enough to fully understand their origins and to use them for a highly valuable rapid estimate of the earthquake magnitude. We show that gravity perturbations are particularly well observed with broadband seismometers at distances between 1000 and 2000 kilometers from the source of the 2011, moment magnitude 9.1, Tohoku earthquake. We can accurately model them by a new formalism, taking into account both the gravity changes and the gravity-induced motion. These prompt elastogravity signals open the window for minute time-scale magnitude determination for great earthquakes.

PMID:
29191903
DOI:
10.1126/science.aao0746

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