Earthquake source complexity.
Earthquake sources reveal spatial and temporal heterogeneities at all scales. In the last 10
years, the increasing number of near-ﬁeld observations and the exponential grow of com-
putational means boosted the seismologists capability of reconstructing the spatio-temporal
evolution of rupture processes during earthquakes. Here, the mathematical representation
of ﬁnite seismic sources will be brieﬂy discussed, together with the methods and the data
most used to setup the earthquake rupture inverse problem. Then, important recent earth-
quakes (including L’Aquila, 2009 and Tohoku-oki, Japan 2011) will be reviewed, discussing
the relevant features of their rupture complexity. Understanding the complexity of seismic
sources, beside the importance from a theoretical standpoint, responds to the fundamental
challenge of improving the prediction of the ground motion variability for future earthquakes,
especially in the near-ﬁeld where usually major damage occurs.