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:

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For anyone interested in applying for a fellowship at Durham University the closing date for Senior Research Fellowships and Policy and Enterprise Fellowships is 27 January 2012.

For further information on all the DIFeREns fellowships, please see http://www.dur.ac.uk/ias/diferens/

For further information on Institute of Advanced Study-supported Policy and Enterprise Fellowships, please contact Colin Bain (c.d.bain@dur.ac.uk).

If you are interested in applying for one of these fellowships with IHRR, please contact Executive Director Prof Dave Petley in the first instance: d.n.petley@durham.ac.uk.

Full details about the Fellowships are on the European Comissions’s website here.

An exciting series of lectures given at the last AGU meeting on the Tohoku earthquake explain a great deal about the tectonic plate interactions that led to the quake along with measuring its magnitude and studying its behaviour which was unusual compared to past large earthquakes.  The Tohoku earthquake was a multi-segment earthquake and while earthquakes occur frequently in this region of Japan, the thrust of this earthquake was entirely unexpected and was characterised by a number of large slips.

There is also a history lesson here.  The tectonic environment of the Tohoku quake was similar to the mysterious, historic 1907 Sumatra Earthquake (7.6 mag).  Although it is difficult to say what happened exactly based on seismograms that were left, the 1907 Sumatra Earthquake may also have been a megathrust event like Tohoku. Read more

Land mines and unexploded ordnances are a serious problem in many parts of the world.  They are a painful reminder that some of the most deadly and dangerous hazards are made by people.  The use of mines in warfare is also far from over.  The governments of Israel, Libya and Myanmar have all been confirmed to be laying anti-personnel mines that are designed to kill people.  There are also a number of countries (such as Russia, China and the US) who have not signed the Ottawa Treaty (Anti-Personnel Mine Ban Convention) that was formed in 1997 in Ottawa, Canada to ban the use of landmines.

While the number of casualties caused by mines and unexploded ordnances has gone down since the 1990s when common estimates were 26,000 per year, according to the Landmine and Cluster Munition Monitor, there were more than 5,000 recorded casualties in 2008.  In 2009 3,956 casualties were reported and 4,010 recorded for 2010.  In 2010, 200km2  of mined areas were cleared by 45 action programmes.  More than 388,000 anti-personnel mines and over 27,000 anti-vehicle mines were destroyed during this clearance.  This was accomplished by anti-mine programmes in Afghanistan, Cambodia, Croatia, Iraq and Sri Lanka, which accounted for more than 80 percent of recorded clearance.  Also, 80 percent of the world´s nations have signed onto the Mine Ban Treaty.  Unfortunately, the US was reported to have slowed down its policy review on the treaty last year.  But even for the countries that have signed on the rate of compliance for submitting annual transparency reports was at an all-time low of 52 percent. Read more

I have spent the last week collecting samples from the rock slopes affected by the Christchurch earthquake sequence, and am now travelling back up to Wellington, where I will spend the coming week. En route I have stopped off for the weekend in Nelson so as to be able to take a look at the landslides at Golden Bay.  These landslides were triggered in an exceptional rainstorm in mid December – I covered it briefly at the time – and have been quite devastating for the local people.

In Golden Bay the most seriously affected area that I saw was the margin of the Abel-Tasman National Park, as shown in the Google Earth image below, especially between Pohara and Tata Beach, although there is almost certainly further problems to the east that I could not access.  The road shown on the map across the area was closed at Tata Beach.

A good overview of the main impacts of this storm is shown below – this is the small community of Ligar Bay, which has been an area of beachside houses, with new subdivisions on the slopes behind.  If you look carefully you will see:

  • Slips below the road affecting the carriageway;
  • Slips on the slopes above the road, which deposited debris that blocked the highway;
  • Multiple slips in the slopes behind the village; and
  • Debris released from those landslides that has then damaged the houses

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