On the 22nd February 2011 just before 1pm a 6.3 magnitude earthquake blasted Christchurch city in New Zealand. We felt it in Wellington about 10 seconds later, on a different island. The faultline had only been discovered as little as six months earlier when a stronger quake struck, but this one was during the day time, was shallower, and hit at the heart of the city during lunch hour:
The effect was devastating, with death and destruction obliterating the central business district. It is New Zealand's
worst natural disaster in our short history.
When the magnitude 7.1 quake struck on September 4th 2010 and continued to linger with aftershocks for months Paul Nicholls at the
University of Canterbury created a mashup using Geonet's
public quake drum data and overlaid it onto Google Maps:
The
resulting visualization is a timelapse display of location, strength and depth of every subsequent quake.
Taking this a step further Chris Crowe uses the same data to
calculate the energy released from the earthquakes:
What both visualizations make clear is that the quakes, while distinct, are part of an ongoing sequence of seismic activity. What is striking about these events are the forces experienced in what was previously thought to be a stable part of the country. The following graph maps the magnitude of each quake to the depth, what is revealing is the shallowness of each quake:
For those of us that live in Wellington an earthquake is nothing new, but when a 4.3 quake struck late in the evening last weekend many of us paused to wonder if Christchurch was hit; thankfully a quick check on Twitter revealed everything was fine down there. The quake was rocky and sharp, here is how it appeared on Geonets quake drum:
To put this into perspective here is an image of the Christchurch drum for the same period:
Our thoughts are with everyone in Christchurch as they cope with rebuilding their city and lives in such a fragile and unpredictable environment.
