An update on the Italian landslide(s)

The large landslide in southern Italy that was graphically caught on camera (see the video in my earlier post) has generated a great deal of interest - indeed this site has had its busiest ever day. Details of the slide are still quite sketchy, but this is what we know so far:

First, the media are confusing two different slides in the same general area of Calabria - in fact there were about 100 altogether, but two are directly affecting towns. The one in the video occurred on the outskirts of Maierato, which is this town:

It appears that the slope had been moving for some days, and there are some indications that it was in distress well before this. The slide appears to have affected the area shown on this image, although I am waiting for clarification of this:

Interestingly, as Jonas van Rutte has pointed out to me, the roads near the headscarp appear to have been recently repaired, judging by the Google Street View images here. No-one was killed or injured in this landslide, although 2300 people have been evacuated from their homes.

The second slide occurred at San Fratello in Sicily, which is this town:

This slide appears to have damaged the centre of the town, leaving 1500 people homeless. The level of damage is high (image from Corriere della Sera):

Watch this! Extraordinary landslide video - Maierato, Italy

See update post here

The BBC has an extraordinary video of a landslide in Maierato in Southern Italy. More later, but for now the link is here:

http://news.bbc.co.uk/1/hi/world/europe/8517378.stm

UPDATE: Youtube has a longer version of the video below:



See update post here

Fatal rockfall near to Munich in Germany

Last night a fatal rockfall occurred at Stein an der Traun in Southern Bavaria. According to this report, which is also the source of the remarkable image above, the block was the "size of a house" (probably something of an over-estimate), falling from the 15 m slope behind the building. There were four people in the house at the time, of which two were killed and two were injured. There is no obvious trigger for the failure.

It is of course too early to speculate about the causes of this sad accident, but in my experience the combination of an unfortunately-orientated discontinuity in the rock (often a joint) and cutting of the toe of the slope to create space for the building are often to blame. It will be interesting to find out what caused this accident.

A first take on the Italy earthquake

You will probably be aware that an apparently quite destructive earthquake struck central Italy overnight. I thought I'd try to give a first take on the likely impact of this event. First, as ever, there is some pretty good information about the earthquake on the USGS Earthquake program website. They have provided the following helpful maps:

Earthquake location:
Shaking intensity:

Exposed population (PAGER):


At this point (c. 8:00 UT) the USGS is estimating that there are about 68,000 people living in areas that have suffered an earthquake intensity of VIII (severe shaking) or above, mostly in the town of L'Aquila. This is an area with a mix of old and new buildings built in a hilly area, as this image (from here) shows:

Although the earthquake is not huge (USGS estimates are Mw=6.3), the shallow depth (10 km) and fairly vulnerable buildings means that the impact could be quite substantial, albeit in a fairly limited area. Italy is well-prepared for earthquake response, which will help.

So, what of landslides? Well, an earthquake of this size should be capable of triggering a fair number of slides. A good starting point is the Keefer (1984) relationship between earthquake magnitude and area affected by landslides:

This gives an area affected by landslides as about 2000 km2 (give or take quite a lot, though). The area is certainly landslide prone, as this Google Earth perspective view shows (I have marked the epicentre location as per the USGS. The town in the foreground is L'Aquila):

Incidentally, the mountain in the background is Gran Sasso, which houses an important particle physics laboratory in a deep tunnel. I would be interested to know how the experiments have fared during the earthquake.

Some landslide images from the Alps

Well, I am finally back - apologies for the prolonged absence! It will take me a day or two to get back up to speed, but in the meantime I thought I'd post four landslide images from Switzerland and France that I took whilst on holiday (I have a very long suffering family...). In each case you can click on the image for a better view. Please feel free to use them in presentations, lectures etc but not commercially.

A large, apparently recent, complex rock fall near to Champery in Switzerland.

Classic ridge splitting and counter scarps, indicating deep seated, slow mass movements near to Leysin in Switzerland.

A recent, shallow slump caused by cutting a road into weak deposits at Chatel in France

An old rock fall deposit above a small settlement near to Chatel in France. I guess that the deposit mostly predates the buildings.