Anomalous enhancement of the ionospheric TEC before Haiti earthquake on 12 January 2010

A major earthquake (M=7.3) occurred in Haiti (18.5°N, 72.5°W) at 21:53 UT on 12 January 2010. On the basis of regular GPS observations from the International GNSS service (IGS) network, Global Ionospheric Maps (GIMs) of total electron content (TEC) from 27 December 2009 to16 January 2010 were analysed. It was shown that there was a significant enhancement of TEC around the epicentre on 11 January 2010, with a maximum of ∼10TECu during 20:00–22:00UT. Taking into account of very quiet solar and geomagnetic activities during this period, we can conclude that the observed anomalous enhancement of the ionospheric TEC was likely associated with the imminent earthquake.