Have a look at this. http://www.geonet.org.nz/earthquake/quakes/recent_quakes.htm... Christchurch, New Zealand. Main quake, 7.1 on the scale (and with hindsight, not all that bad), was almost six months before a very shallow 6.3 aftershock which was very bad and had lots of deaths. So far there have been something like 8000 aftershocks. People from the area often seem shell-shocked.