Ned Bair, ESM 595PB 11/24/2008

Why are some avalanches much deeper than others?

•Buried parking lot under 20 feet of snow including 4 people in the parking lots, whom were all killed.

•total loss: $1.6 million

•12 people buried, 7 killed.

Remnants of the Summit Lodge

The avalanche wolf was at the door all along, but, like the Cheshire cat, he had faded to nothing more than a grin, the fangs barely visible. In 1982, Nature called out the wolf pack.

13–year old boy blown out of a chairlift, buried, and killed at the Las Vegas Ski and Snowboard Resort (LVSSR).

Resort has been in operation since 1962.

Average snowfall ~ 10 feet. This storm dumped 8 feet in 2 days.

LVSSR still in litigationover wrongful death.

Remnants of a trailhead bathroom at Mt Charleston struck by 1/9/05 avalanche

The problem with the 1982 Alpine Meadows avalanche was that it was a 100-year path, but Alpine Meadows had only been in operation since 1961.

Likewise, Las Vegas Ski and Snowboard Resort had been in operation since 1962. Workers reported clearing 500-year old trees from the debris in the summer of 2005, suggesting a return-period that was an order of magnitude greater than the resort’s history.

Given perfect information, we could know exactly where we are, at all times, on the cumulative distribution function

With perfect information,resort managers could close and evacuate the areaduring times of extremehazard.

We are here almost all of the time

3/31/1982

Find days that are most like today based on Euclidean distance to a number of meteorological and snowpack variables. Extreme weather is associated with extreme avalanche activity!

Figure out where we are on the CDF, then act accordingly. If we get the functional form of the CDF right, then we can extrapolate past what has been experienced.

2( , ) ( )L Y Q a Q Y Where Y is decision to close Y resources. These could be lifts, runs, or buildings.

Q is uncertain. It is the number of resources threatened by avalanches on that day. Q is proportional to the magnitude of avalanches that day.

a is the loss per resource.

The squaring makes L symmetric so that closing too many resources incurs the same loss as closing too few resources.

( ) ~ ( 0.35, 0.16, 0.55)P Q gev k

( | ) ~ ( 0.01, 0.11)P Q Q N

( ) ~ ( 38.7)P Q Exp

( | ) ~ ( 24, 35)P Q Q N

23924, 35

0 0

( ) ( )NNV Y a Q Y N Exp dQd

20.35, 0.16, 0.550.01, 0.10

0 0

( ) ( )GEV kV Y a Q Y N GEV dQd

0 0

( ) ( , ) ( | ) ( )V Y L Q Y pdf Q Q pdf Q Qd

NN is more complex, so it is less reliable. The cost vs. the gev is that sometimes NN will crash.

Also, NN probably takes an hour longer to run.