11 December 2013

AGU Fall Meeting 2013: the first two days

Posted by Dave Petley

Two days into the AGU Fall meeting and I feel exhausted already!  As usual it is a modern day equivalent of the biathlon, consisting of mad dashes between sessions (carefully arranged to be the maximum distance apart) followed by a need to concentrate intensely for something between 15 minutes and two hours.

it is had to identify the highlights s there has been so much good stuff.  I should wave the flag for my team first – in particular a paper by Nick Rosser (on which I was a minor co-author) on the long term monitoring that we have been undertaking on the cliffs of North Yorkshire.  This is a ten year (and counting) project with an amazing dataset, beautifully presented by Nick.  In the same session Colin stark presented his work on characterising giant landslides using the global earthquake network.  This is research that never ceases to impress, and it is allowing an understanding of the magitude-frequency relationships of these big slides.  The verdict – they occur far more often than we realised, and events that we would have mapped as a single landslide from the deposit are often a series of events in reality. Speaking of which, Runqiu Huang presented work from Chengdu University of Technology on the giant landslides from the Wenhuan earthquake, including the largest slide in the last three decades at Daguangbao (>1.2 cubic kilometres!).  The most interesting aspect of this work was a new model for large seismically triggered landslides, which suggests that they tend to have a steeped rear scarp and a lower angled sliding surface at the toe, forming  chair shape, when compared with hydrologically triggered slides.  That is an interesting idea that deserves further attention.

Jonathan Godt of the USGS presented some work that they have been doing on the landslides triggered by the extreme rainfall event in Colorado this summer, in which there were three fatalities from landslides.  I will try to track down some images of the landslides, but in the meantime there is a very interesting paper about them here (NB pdf).  In the poster session today Kerry Leith and colleagues presented a fascinating model on the evolution of landscapes during and between glaciations, and the way that the resultant stress state controls the processes that occur after the first ice age.  I won’t say more here as the team deserves to present this material for themselves, but the ramifications in terms of our understanding of mountains are profound.

Away from landslides, James Elsner presented a fascinating paper that explored whether tornadoes in the US are becoming more energetic, a vastly complex topic.  To do so required a very detailed and complex re-analysis of the underlying tornado dataset – this was very rigorous and impressive (but no doubt the climate skeptics will wrongly misinterpret this as being some sort of fudge).  Th resulting data suggests that US tornado energy dissipation has increased dramatically in recent years.  Elsner did not want to link that to climate change – sensibly – but the trend in itself is deeply alarming.

There is so much good work that I haven’t been able to mention – the quality is incredibly high from start to finish.  And of course the meeting rolls on – this afternoon to the bloggers forum (where my AGU blogging colleagues are on the panel) and then this evening to the Natural Hazards reception.   My papers are tomorrow and on Thursday, so for me the real action is yet to come.