Mysterious behavior of ionosphere immediately before and after large earthquakes

2016 Fiscal Year Final Research Report

• Project/Area Number: 26400442
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Solid earth and planetary physics
• Research Institution: Hokkaido University
• Principal Investigator: Heki Kosuke 北海道大学, 理学研究院, 教授 (30280564)
• Project Period (FY): 2014-04-01 – 2017-03-31
• Keywords: GNSS / TEC / 電離圏擾乱 / 地震前兆 / 三次元構造

Outline of Final Research Achievements

I studied anomalies of ionospheric total electron content (TEC) related to earthquakes using GNSS satellites. The quantitative relationship between the magnitude and coseismic TEC pulsation has been established. Preseismic ionospheric changes have been discovered shortly after the 2011 Tohoku-oki earthquake. I collected similar observation cases before over ten large earthquakes with moment magnitudes (Mw) 7.8-9.2, and revealed several kinds of Mw dependences of these anomalies, e.g. precursor times (40 min. for M9 and 20 min. for M8 events), spatial dimensions, and strength of preseismic changes in terms of changing rate of TEC. From 3-D structure of ionospheric anomalies, it was found that the preseismic ionospheric anomalies are due to positive electric charges on the surface.

Free Research Field

地球惑星物理学