Another large shake on both sides of Cook Strait is highly likely over the next week, experts say.
The chance of a jolt of at least magnitude 5 in the next seven days is 82 per cent, according to GNS Science seismologists, and the likelihood of a magnitude 6 or more quake is about 16 per cent.
Seismologist Caroline Holden warned people to be vigilant and expect another large shake. Since Friday afternoon’s 6.6 tremor, there had been another 62 aftershocks reaching magnitude 4 or more, by yesterday evening.
Dr Holden’s colleague Martin Reyners said the area near Seddon where the earthquakes were recurring was known as an active one. There was a magnitude 6 quake there in 1966, and another in 1977.
The level of horizontal acceleration, which is the amount of movement people feel from a quake, was similar to that felt during the Christchurch earthquakes, but not as significant.
‘‘It’s a different experience for everyone, depending on what soil your house is built on. At its worst acceleration, there were reports of people not being able to stay standing upright,’’ he said.
The sequence of quakes was slowly tracking southwest, away from Wellington, but on to land in Marlborough.
‘‘Friday’s quake was situated so that the people of Seddon were sitting pretty much on top of it, which explains the damage. Each quake changes the stresses in the fault. In areas where the stress has gone up, near a fault, it can trigger another event.’’
In the case of the recent quakes, there had been some triggering as the stresses shifted south. This would mean the effects would be felt less in Wellington, but more in Seddon.
- © Fairfax NZ News
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