Preseismic TEC Changes for Tohoku-Oki Earthquake: Comparisons Between Simulations and Observations

  • Author(s): Cheng-Ling Kuo, Lou-Chuang Lee, and Kosuke Heki
  • DOI: 10.3319/TAO.2014.08.19.06(GRT)
  • Keywords: Earthquake precursor, Total electron content anomaly, Tohoku-Oki earthquake
  • Citation: Kuo, C. L., L. C. Lee, and K. Heki, 2015: Preseismic TEC changes for Tohoku-Oki earthquake: Comparisons between simulations and observations. Terr. Atmos. Ocean. Sci., 26, 63-72, doi: 10.3319/TAO.2014.08.19.06(GRT)

Heki (2011) reported that the Japanese Global Positioning System (GPS) dense network detected a precursory positive total electron content anomaly (TEC), with ΔTEC ~3 TECU, ~40 minutes before the Tohoku-Oki earthquake (Mw 9.0). Similar preseismic TEC anomalies were also observed in the 2010 Chile earthquake (Mw 8.8), 2004 Sumatra-Andaman (Mw 9.2) and the 1994 Hokkaido-Toho-Oki (Mw 8.3). In this paper we apply our improved lithosphere-atmosphere-ionosphere (LAI) coupling model to compute the TEC variations and compare the simulation results with the reported TEC observations. For the Tohoku-Oki earthquake simulations we assumed that the stressed associated current started ~40 minutes before the earthquake, linearly increased and reached its maximum magnitude at the time of the earthquake main shock. It is suggested that a dynamo current density of ~25 nA m-2 is required to produce the observed ΔTEC ~3 TECU.

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