  Contrary to common belief, as the time since the last earthquake in a certain
region increases, the risk of occurrence of another earthquake diminishes. As a
consequence, the expected waiting time to the next event increases with the
elapsed time, in other words, the event moves away to the future faster than we
move. This paradoxical phenomenon is found in regions as diverse (from a
tectonic point of view) as California, Japan, New Zealand, Spain or the British
Islands, as well as in worldwide scales. This behaviour shows a surprising
regularity, since in all the cases it is well described by the same universal
scaling functions. This universality suggests the existence of a common simple
physical mechanism in the earthquake generation process.
