The Interior of the Earth

Abstract

The interior of the earth (and of the other planets) is much less known than the surface of celestial bodies light-years away and also the interior of the sun. In fact, the physics and chemistry of solid and liquid phases, which are relevant for the planets, are much more complicated than those of nearly perfect gases (which form the stars). Moreover, the main source of information at our disposal — the propagation of seismic waves throughout the planet — is usually not under control of the geophysicists, but depends on the sudden occurrence of unpredictable events, the earthquakes. On the other hand, a planet is a complex machine whose internal processes continuously and deeply influence the morphology and the dynamics of the crustal layer, as well as the composition of the atmosphere. In this chapter, we describe how the seismic “probe” works, how quantitative models of the structure and of the thermal processes of the interior are built and, finally, the dynamical response of the surface layer to these processes, i.e., the so-called global tectonics.