A v a l a n c h e

C o n t r o l ,

R e s c u e

a n d

E d u c a t i o n

to depth hoar development in thesnowpack. See Elder and
Newcomb (1994,1995) forphotographs of the site.

FIELD METHODS

Transectsofdepth, snowwaterequivalence and ramre-
sistance were completed in 1993.Transects of depth and
ramresistance werecompleted in1994,1995and1996.
Snow pits were excavated during the field work to check
temperature and stratigraphy, primarily to insure that the
snowpack was still cold and had not undergone melt.A
total of 28 ram profiles were taken in 1993, and 81 profiles
were completed in 1994. Samples sizes were 29 and 16 for
1995and 1996,respectively.

RESULTS

Measured snowdepth and ramresistance are plottedin
Figures 1through 3.Figure 1 shows the cross-slope pro-
files ofsnow depth,integrated ram resistance, and mean
ram resistance through GAZ-EX 4 and 1.The two vertical
linesrepresentthelocationsoftheblasters:leftmostis
number4,rightmost isnumber1.Note that although the
accumulation was greater in 1995 and 1996as compared
to 1993 and 1994, similar spatial trendsare seen amongall
the years.The lines represent smoothed fitsof the point
data;pointvalues are plottedwith thelastdigit oftheir
year of collection (e.g. 3 is from 1993).Figure 2 shows the
down-slope profile of snowdepth,integrated ram resist-
ance,and mean ramresistance at GAZ-EX1.Again,the
vertical line represents thelocation of the blaster. 1996 was^{sents the location of the blaster. No data was collectedat this site in}
a heavieraccumulation yearthan 1993or1994and ram^{1993 or 1996.}

resistance reflects the difference in magnitude,however,
the spatial trends are similar. No data was collected at this
site in 1995. Finally, in Figure3 is plotted the down-slope
profile of snow depth, integratedram resistance, andmean
ram resistance at GAZ-EX 3.The vertical line represents
the location of the blaster.1995 was a heavieraccumula-
tionyearthan1994andramresistancereflectsthe
differencein magnitude again. However, the magnitude of
thedifference ismuchlargerthan inothercomparisons
and the spatialtrends arenot similar. Notable is the lack of
influence in 1995when the blasterwas not working.No
data was collected at this site in 1993or1996.
Investigations of the snowpack at the GAZ-EX installa-
tion in the Glory Bowl slide path on Teton Pass indicates
that:

*ashallowsnowpackismaintainedintheblastzone
when compared to surrounding terrain,

*the area affected in terms of snow depth is about 10 to
40mfrom the GAZ-EX legs,dependingon year and di-
rection of measurement,but maybe greaterin down-
slope cases,

*aweak snowpackdominated bydepthhoarexistsin
theblastregionwithincreasingramresistance
observed with greater distance from the blast area,

*the radius of influence for ram resistance is about 10 to
35mfromtheGAZ-EXlegs,dependingonyear
and direction,

*althougheffectiveinremovingnewsnowabovethe
depth hoar before it gains strength, the GAZ-EX is not
effective in removing the depth-hoarsnowpack in the
blast area.

Figure 2.Down-slope profile of snow depth, integrated ram resistance,

and mean ram resistance at GAZ-EX 1. The vertical line represents the

location of the blaster. No data was collected at this site in 1995.

258