48o0' N
128oW
122o W
48o N
0
200 km
N
857
BRITISH
COLUMBIA
TO
Va
nc
ou
ve
rI
s.
Study
area
50o N
W
AS
HI
NG
Mid
dle
Vall
ey
130o W
End
eav
our
Seg
me
nt
48o5' N
We
st V
alle
y
129o W
Inferred zone of
0.35 m opening
1024
1025
1027
0
20 Kilometers
VOLCANO DEFORMATION–
Geodetic Monitoring Techniques
By Daniel Dzurisin
U.S. Geological Survey graphics