Yesterday, Christchurch experienced one of the strongest after-shocks, more than six weeks after the major earthquake of Sept 4th. Listen to Sept 4th 2010 and news stories the following two weeks. Although this after-shock was only 5.0 on the Richter scale, it was near the city and shallow – only 5km deep – so it felt strong. It happened at 11.30am, when people were at school, work or shopping; in fact many men were on roofs repairing chimneys, and in one case, some workmen were on top of a seven-storey building, starting to demolish it. However, no one was injured. There have been more than 2,000 after-shocks in the last six weeks, most of them small. Geologists have said that after-shocks will continue for some months yet, although they will not be so often.
On the same day, 1200 people received phone calls from the Earthquake Commission telling them that their houses could be re-built after the land has been stabilised. Only 16 homes cannot be re-built because it is impossible to stabilise the land. Tomorrow, all these people will receive detailed information from the Earthquake Commission by courier post. These people have so many questions: Will my house have to be demolished? How can the soft land be stabilised? How long will it take? Will insurance companies insure my new house? and so on.
We will not know all these answers for a long time.
Questions1. How do you think people feel after so many after-shocks?
2. How do Geologists know that after-shocks will continue?