The dynamics of a seismic wave field: Animation and analysis of kinematic GPS data recorded during the 2011 Tohoku-oki earthquake, Japan

Abstract

[1] During rupture, earthquakes induce permanent and dynamic ground displacements that can be measured by GPS. More than 1200 continuous GPS stations distributed throughout Japan recorded the displacements due to the March 11, 2011, Mw9.0 Tohoku-oki earthquake. We animate these data, which shows the growth of the earthquake rupture over time and illustrates differences of earthquake magnitude through two smaller aftershocks. We also identify dynamic ground motion due to S-waves (body waves), Love waves and Rayleigh waves (surface waves) in this data set. Real time availability of such displacements could be of great use in earthquake response and tsunami warning, and to some degree in earthquake early warning. We find that the length of the ruptured fault can be approximated from displacements which could allow rapid identification of areas prone to large aftershocks. We outline a method that integrates real time displacements into an earthquake alarm system. The animated displacements in map view are easily understandable by specialists and non-specialists alike and hence provide a valuable education and outreach tool.