The recent earthquake sequence in Christchurch has of course heightened awareness of seismic hazard in New Zealand. On the way across South Island last weekend I stopped in the town of Murchison, after which the 1929 earthquake is named. This was a large event – the estimated magnitude is Ms=7.8, such that shaking was felt across much of New Zealand. Fortunately, at the time this central region of the South Island was very sparsely populated, so the number of casualties was limited to just 17 people.
From my perspective the interesting aspect of this is that it triggered many landslides. The distribution of these landslides is currently being analysed by a team of people from GNS Science and Durham, and in particular by my PhD student Rob Parker. These slides are interesting for a number of reasons, not least is that they were responsible for much of the loss from the event. Indeed, 14 of the 17 deaths occurred as a direct result of landslides. Furthermore, it is thought that 38 valley blocking landslides occurred, and 21 of these still retain lakes.
The legacy of the earthquake is still clearly evident in the landscape. Perhaps most obvious is the fault scarp, which is marked by a waterfall at the point at which the fault crossed the Buller River. There is a viewpoint to allow the passer-by to stop – it is a really impressive feature:



