Ionospheric abnormality before the 26 December 2004 M9.3 Sumatra earthquake is detected by the total electron content
(TEC) of ground-based receivers of the global positioning system (GPS) in the Indian Ocean area. Higher spatiotemporal
grids of VTEC than earlier research are computed. To identify the abnormal ionospheric-seismic signals before
the earthquake, a method of statistical analysis is utilized, and the temporal solar activity and geomagnetic environment
is also considered in this paper. Results indicate that VTECs mostly decreased 4 days before earthquake happening, and
quickly come back after the tragedy. We also find that areas of ionospheric-seismic anomalies is in ±15° latitude deviate
from epicenter, and the anomalies are more obvious in the sea than the earth, so we can deduce that correlations of
ionosphere with seabed and earth are different to some extent.
|