A Word About Aftershocks

The 4th of September 2010 at 4:35 am turned many people in Canterbury's lives around. It's epicentre was very near a place called Charing Cross, which unlike its London namesake, is hardly a bustling centre of activity, even though it's an intersection of six roads. The nearest towns are Darfield, Kirwee and West Melton. It's roughly halfway between Darfield and Burnham Military Camp. It's roughly 40 km's from where I live in Christchurch and unusually for New Zealand, the road distance is not much longer than the distance a harrier might fly to get there.

When we were all awoken that morning, Canterbury residents got a crash course on what it's like to live in a quake zone. Pretty soon the reason why so many Canterbury residents struggled to get a good nights sleep for the next few weeks made its presence felt. Aftershocks. There were several big ones following the main quake. All were preceded by the ominous rumble. Something that worried us all was the geologists saying there is always a large aftershock one magnitude unit less than the main quake.

The Wednesday following the earthquake there was a particularly nasty aftershock. It had us running for the door frames. After it finished, I breathed a sigh of relief. "There's our big aftershock", I told the family. But no. It was 5.1 on the Richter Scale. That was a lesson in proximity and depth of an earthquake.

As the months went past, so did the threat of a large aftershock. We were told to expect a magnitude 5 or more aftershock every four or five weeks. While we were in Auckland, Christchurch had a 5.1 aftershock. About five weeks after that, we had the deadly 6.3 aftershock. It started its own aftershock cycle. Only 15 minutes afterwards, a 5.7 aftershock hit the city. This one on its own was bigger than any of the aftershocks following the September earthquake. Mid afternoon, another one struck, this time 5.5 but very frightening.

The September earthquake and the February aftershock have been frightening enough, but for the hours, days, months afterwards, peoples anxiety levels are high. Some people outwardly are quite relaxed about aftershocks whereas others find them difficult to cope with. When I say difficult, I mean they can be absolutely hysterical when they strike.

I probably fall into the relaxed category with aftershocks, but that doesn't mean that I'm not anxious over them. After six months, my heart pounds and I hold my breath when I hear the familiar rumble. As I write, a 3.7 aftershock struck and even though it's relatively small, it was quite sharp. Half an hour later, I've finally calmed down.

There's been about 5000 aftershocks since September. Don't know for how long they are going to go on for.