Nasa has published a map linking the September 2010 7.3 magnitude Christchurch Earthquake with the devastating quake on February 21, 2011. The map indicates many events over the past 6 months, but not the thousands reported elsewhere.
With this in mind I’ve re-used the framework from another mapping project I’m working on, and put together a time lapse video displaying the full set of seismic data for this time period. The dataset comes from the New Zealand GeoNet Project – an organization that operates a geological hazard monitoring system for New Zealand.
The visualization covers an area of about 10,000 square km around Christchurch, includes 4,300 earthquakes since September 3 2010, and is bookended by the 7.3 magnitude event from last year and the disaster from a couple of days ago.
- Each animated red circle represents an quake or aftershock. These are scaled according to strength.
- The orangey-coloured static dots underneath represent epicentres.
- Dates are in UTC/GMT
- The video is hi-def. Click the options once it’s playing to see it in higher quality.
The British Geological Survey have an interview with Seismologist Dr Roger Musson on Youtube, providing some insight into this progression of aftershocks. To paraphrase him, after the Darfield earthquake the aftershock sequence followed the typical pattern of gradually tailing off. With events diminshing in magnitude and frequency. Occasionally, towards the end of a pattern like this, there’s another major event and it starts over again. Sadly this what appears to have happened in Christchurch.