Posted in Thesis on 10/27/2008 06:51 pm by Mika
From Geohazards IV paper:
For rock avalanches, the frictional resistance model typically produces reasonable simulations of the observed runout distance. Hungr and Evans (1996) and Pirulli (2005) used DAN-W to back-analyze 34 different rock avalanches using the frictional resistance model. The calibrated φb values ranged between 8º and 23º with a mean of 16º. For the Canadian cases, the best result with the frictional rheology falls within this range with and φb of 20º.
Hungr and Evans (1996) also noted that the Voellmy rheology produced consistently good debris distribution, velocity profile, and runout distance for f values between 0.03 and 0.24 and ξ between 100 and 1000 m/s2. Only events involving runout across a glacier or substantial entrainment combined with channelization had calibrated coefficients less than 0.1. For the Canadian cases, the best results were obtained with Voellmy as the dominant rheology, with f between 0.02-0.15 and ξ between 250-500 m/s².
Posted in Thesis on 09/12/2008 07:48 pm by Mika
On September 12th, 1717, a huge landslide came down off Mont Blanc in the Alps and ran across Triolet Glacier. Boulders, water, and ice were entrained in the flow. The landslide killed 7 men, 120 oxen or cows, and destroyed a whole lot of cheese (Grove 2004). The travel path came down the slope, splashed up the valley side, then continued down the valley about 5 km (Grove 2004 citing De Tillier 1968 & Porter and Orombelli 1980).
Triolet Glacier on Mont Blanc: location of the profile. Image credit to Google & HeyWhatsThat.com.
From Grove, “The debris of the giant rockfall from the Aiguille de L’Eboulement which swept the Triolet glacier in 1717 is estimated to have a volume of 16-20 million cubic meters and have descended 1860 m over a distance of 7 km in a few minutes.” However, this debris distribution has been revised quite a bit by other authors — Deline and Kirkbridge (2008) vastly reduced the scale of the event to 7.3-9.8 million cubic meters with the deposit covering 2.9 square kilometers to a depth of 2.5-3.4 meters.
Profile of Triolet Glacier: this is the cross-section I’m using for my DAN-W model. Image credit to HeyWhatsThat.com.
So far, modeling it hasn’t worked for me. I suspect this is because glaciers are slippery.
