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Solid Earth and Upper Atmosphere Coupling

A systemic approach is applied to Earth in order to discriminate and correlate the various processes and interactions. Geosystemics (De Santis, 2009) studies the Earth system from a holistic point of view. Earth planet is thus considered as a whole and unique far-from-the equilibrium complex system, formed by numerous different parts (sub-systems), which do not act independently but interact each other continuously. Most interactions are nonlinear, so that we can usually say that "resultant is more than the sum of the parts". Interactions are not only in terms of contrasts but, and mostly, cooperative and mutual organizations. This is the case of the interactions and couplings between the three mechanical components: the solid earth and the two fluid parts, atmosphere and oceans. Each component interacts with the others in complex ways and on various time and space scales. For instance, sources in the solid Earth generate waves propagating in the atmosphere which in principle allow us to better quantify extreme events, such as earthquakes and volcanic phenomena.

As a case study (Cianchini et al., 2009), we show the application of this approach to the big earthquake of Sumatra (M=9.1, 26/12/2004) analysing the magnetic data of CHAMP satellite (Figure 1).

Figure 1 Spatial distribution of CHAMP orbits on 26 December 2004. The small star in the lower part of the globe indicates the position of the earthquake epicentre.

We applied some concepts of the Information Theory (a Spherical Shannon Information) to the magnetic satellite data showing a trend change of this quantity just after the earthquake (Figure 2). This change cannot be justified by an external source.

Figure 2 Shannon information (top curve) deduced from Gauss coefficients of a spherical harmonics inversion of daily geomagnetic satellite (CHAMP) data, together with the rescaled daily sums of the planetary magnetic index  (bottom curve). The star indicates the day of the Mw 9.1 Sumatra earthquake


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