MW9 Tohoku earthquake in 2011 in Japan: precursors uncovered by natural time analysisReport as inadecuate

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Earthquake Science

pp 1–9

First Online: 27 July 2017Received: 29 January 2017Accepted: 20 June 2017


This paper reviews the precursory phenomena of the 2011 MW9 Tohoku earthquake in Japan that emerge solely when we analyze the seismicity data in a new time domain termed natural time. If we do not consider this analysis, important precursory changes cannot be identified and hence are missed. Natural time analysis has the privilege that enables the introduction of an order parameter of seismicity. In this frame, we find that the fluctuations of this parameter exhibit an unprecedented characteristic change, i.e., an evident minimum, approximately two months before Tohoku earthquake, which strikingly is almost simultaneous with unique anomalous geomagnetic field variations recorded mainly on the z component. This is consistent with our finding that such a characteristic change in seismicity appears when a seismic electric signal SES activity of the VAN method from the initials of Varotsos, Alexopoulos, Nomicos initiates, and provides a direct confirmation of the physical interconnection between SES and seismicity.

KeywordsSeismic electric signals VAN method Natural time analysis Earthquake prediction  Download fulltext PDF

Author: Panayiotis A. Varotsos - Nicholas V. Sarlis - Efthimios S. Skordas - Mary S. Lazaridou-Varotsos


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