NJIT Physics Dept Seminar
December 8, Thursday (* SPECIAL DAY*)
Precursory equatorial ionization anomaly intensity variation studied with satellite plasma measurements associated with lithospheric activities: A possible way to predict large earthquakes?
Prof. Kwangsun Ryu
Satellite Technology Research Center
KAIST, South Korea
(Terrestrial Physics, Host: Hyomin Kim)
SPECIAL TIME: 10:15am-11:15am with 10am tea
SPECIAL ROOM: Tiernan 373
Satellite observations of ionospheric disturbances in relation to the occurrence of the M8.7 northern Sumatra earthquake of 28 March 2005 and M8.0 Pisco earthquake of 15 August 2007 reopened a need to investigate the possible correlation between the EIA intensity and pre-seismic activities in the lithosphere. The DEMETER (Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions), CHAMP (Challenging Mini-satellite Payload), DMSP (Defense Meteorological Satellite Program) satellite data were investigated to find possible precursory and post-event phenomena. It was found that EIA (Equatorial Ionization Anomaly) strength expressed in the apex height, derived from the CHAMP plasma density profile, was intensified along the orbits whose longitudes were close to the epicenter within about a week before and after occurrence of the earthquake. Increases in electron and O+ density along the orbits close to the epicenter were also observed in the DEMETER measurements. To investigate whether the link between seismic activity and EIA (equatorial ionization anomaly) enhancement is also valid for mid-latitude seismic activity, a case study on the M7.9 Wenchuan earthquake of 12 May 2008 and a semi-statistical analysis on seven large earthquakes (M > 6.8) that occurred in the north-east Asian region during the DEMETER operation period were executed. The results suggest that mid-latitude earthquakes also do contribute to EIA enhancement, represented as normalized equatorial Ne, and that ionospheric change precedes seismic events, as has been reported in previous studies. According to statistical studies, the normalized equatorial density enhancement is sensitive and proportional to both the magnitude and the hypocenter depth of an earthquake. The mechanisms that can explain the contribution of activity to EIA variation are briefly discussed based on current explanations of the geochemical and ionospheric processes involved in lithosphere–ionosphere interaction.