Aftershock or Foreshock?

With the devastating earthquake in Canterbury two days ago, there’s not much that anyone else in New Zealand is talking about. The area was hit by a bigger earthquake last September, but because it was further away and in the middle of the night, there was no loss of life. Unfortunately, the earthquake that hit on the 22nd was at lunchtime and much nearer to populated areas. Reports are still coming in of damage, loss of life, and people reported missing. The stories that are coming out from survivors are only a reflection of the devastation that the residents are going through.

Something that was brought to my attention by a friend is that this 6.3 magnitude quake is still classed as an aftershock of the 7.1 earthquake on September 4th. Usually aftershocks are associated with smaller, less destructive quakes that happen fairly soon after the initial quake. Still, experts say that the two big quakes are definitely related to each other. More interesting, though, is that, according to the Wikipedia entry: “An aftershock is a smaller earthquake that occurs after a previous large earthquake in the same area (the main shock). If an aftershock is larger than the main shock, the aftershock is redesignated as the main shock and the original main shock is redesignated as a foreshock.” I suppose some things have to be redesignated sometimes, but it would make sense to me if there were more than one word for aftershock, to include whether it was bigger or smaller in magnitude?

Linguistic anomalies aside, there is a good summary of ways to donate money and time on the NZ Herald site, and if you have an offer of a place to stay for displaced Cantabrians, register on Quake Escape. Our thoughts are with the people of Canterbury.

Comments on Aftershock or Foreshock?