Articles | Volume 23, issue 6
https://doi.org/10.5194/npg-23-467-2016
https://doi.org/10.5194/npg-23-467-2016
Research article
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19 Dec 2016
Research article | Highlight paper |  | 19 Dec 2016

Slow strain waves in blocky geological media from GPS and seismological observations on the Amurian plate

Victor G. Bykov and Sergey V. Trofimenko

Abstract. Based on the statistical analysis of spatiotemporal distribution of earthquake epicenters and perennial geodetic observation series, new evidence is obtained for the existence of slow strain waves in the Earth. The results of our investigation allow us to identify the dynamics of seismicity along the northern boundary of the Amurian plate as a wave process. Migration of epicenters of weak earthquakes (2 ≤  M ≤ 4) is initiated by the east–west propagation of a strain wave front at an average velocity of 1000 km yr−1. We have found a synchronous quasi-periodic variation of seismicity in equally spaced clusters with spatial periods of 3.5 and 7.26° comparable with the length of slow strain waves. The geodetic observations at GPS sites in proximity to local active faults show that in a number of cases, the GPS site coordinate seasonal variations exhibit a significant phase shift, whereas the time series of these GPS sites differ significantly from a sinusoid. Based on experimental observation data and the developed model of crustal block movement, we have shown that there is one possible interpretation for this fact that the trajectory of GPS station position disturbance is induced by migration of crustal deformation in the form of slow waves.

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Short summary
We have obtained new evidence of the existence of strain waves in the Earth based on a statistical analysis of the dynamics of seismicity along the northern boundary of the Amurian plate and the data derived from in situ GPS experimental observations. Our results (the periodicity of the seismic components, spatial cycles of the seismicity maxima and migration rate of earthquakes) allow us to identify the dynamics of seismicity along the northern boundary of the Amurian plate as a wave process.