Seismological aspects of intermediate and small-scale upper mantle structure : considerations on a global and regional scale

Seismology can be defined as the mathematical and physical study of earthquakes. It is also the study of how the earth's vibrations, generated by earthquakes, can be used to make statements about the internal structure of the earth. Part of the seismological community focuses its attention on the mechanism of the source. The aims are to unravel the characteristics of the rupture process, in time as well as in space, and to come to a statistical description of the temporal and spatial distribution of earthquakes. Another group of seismologists is concerned with the propagation of the energy which is released when an earthquake occurs. This energy propagates along the surface (surface waves) and through the interior of the earth (body waves). This field of seismology is occupied with the description of the wavefield and the effects on the wavefield caused by heterogeneous earth structure along the propagation path