  Earthquakes rank among the most destructive manifestations of the Earth's
dynamics. Can they be predicted? This is often the first question students ask.
To answer that right away: no, at present it is not possible to anticipate the
date, site and magnitude of future seismic events. However, there does exist a
general framework to describe observations related to earthquakes and
understand the processes that lead to their occurrence: the seismic cycle. This
chapter introduces the reader to the friction laws from a historical to state
of the art perspective. It then deals with mechanical modelling of the seismic
cycle through simple analog models and finally presents some open questions and
directions for future research.
