Hashtag for earthquake in twitter!/nz_quake
Latest Tweets

It is 4.10 and earthquakes happen and we are sitting on the 4th level of a concrete building.
3.5M, depth: 12km 4/10/2010 16:17
3.4M, depth: 12km 4/10/2010 16:08
3.3M, depth: 12km 4/10/2010 16:03

This site allows you to see the magnitude of the quakes in picture form.

This one tells you exactly where the earthquake happened.

From Geonet site

You take the longitude and latitude of the quake and place it in itouchmap and it finds the exact location.
A blog of the event.