TEC anomalies following the 11 March 2011 Tohoku earthquake observed by a dense GPS array

Nowadays, Global Positioning System (GPS) has been widely used to sound the atmosphere and ionosphere. The high resolution and accurate atmospheric sounding from ground and space based GPS will provide new opportunity to investigate seismo-ionospheric disturbances and behaviors before, during or after the earthquake. In this paper, the ionospheric disturbance behaviors following the March 11 Mw=9.0 Japan earthquake in 2011 are investigated using a dense GPS array from Japan GPS Earth Observation Network (GEONET) with more than 1200 continuous stations. The pre-/co-/post-seismic ionospheric disturbances are found from GPS-derived TEC time series during this event. Significant co-seismic ionospheric disturbances are observed with up to 2 TECU. The most propagation mode is range from 2000 m/s to 3200 m/s, 500 m/s to 1200 m/s and 120 m/s to 270 m/s.