What an earthquake feels like

People in Australia have often asked me what an earthquake feels like. Most Australians have never felt one before. It feels a little like being on a roller-coaster ride but without a seat belt on. If you’re inside a house the furniture rocks, slides, or tips and you can hear things fall and smash. If it’s night-time you are plunged into darkness. You call out to your children but can’t hear your own voice because the rumbling of the earth and the shaking of the house obscures it. You can never be fully prepared because they strike so suddenly and without warning. Even running to the nearest door frame is a risky undertaking: imagine trying to walk on a roller-coaster mid-ride. If your children are in another room then you feel totally helpless and unable to reach them.

I’ve heard people question why Christchurch is experiencing so many aftershocks compared with places like Haiti and Japan. I am not a geologist but as far as I’m aware those places have also experienced aftershocks commensurate with the size and location of the initial earthquake. There is nothing unexpected about the sequence of aftershocks in Christchurch. Haiti does not have the huge network of seismic instruments that Christchurch has so many of the aftershocks simply go unrecorded. While Japan does have a dense network of seismic instruments the initial earthquake was offshore – some 160km offshore – where there are no instruments.

The Mag. 6.3 earthquake we had on June 13th was about 10km SE of Christchurch. This makes a huge difference to those of us north of the city. Nothing in our house fell over. It’s fair to say I have secured pretty much everything now and have removed all the pictures from the walls of our house. But there are still some unsecured items of furniture like our washing machine. I heard through a friend who lives on the hill just above the epicentre that their washing machine toppled over. I can’t help but wonder what would happen if the next Mag. 6+ is under our house.

3 Comments

  1. Hi Rachel,I saw an article on Aftershock experiences recently. According to "The Press":-"As of early June, Haiti had experienced 42 aftershocks, Japan 726 aftershocks and Canterbury over 7000 aftershocks. Is there any recording, worldwide, of as many aftershocks as this? Is this related to volcanic activity? – R Brown and G Symes (separately).Part of the answer:-The discrepancy in the number of earthquakes is related to the density of the seismic network (ie, the number of seismic instruments) and the location of the earthquakes relative to the seismic network. The Canterbury region has a very dense seismic network and the Canterbury earthquakes are located close to the instruments." It's good to know you're not leading the world in aftershock activity.

  2. Thanks for that. I read also one of the scientists trying to dispel fears that the volcano was reawakening from extinction. Apparently there's no magma there. The closest magma chamber is in the north island and it can't travel horizontally underground. Phew. We're not facing an imminent eruption of the Port Hills.

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