GEL
STO
100
SAU
HEL
SKA
0
1,000 STO
800
–100
BUR
–200
–300
Nanostrain
Nanostrain (extension – >)
200
27
BUR
400
200
17
26
SKA
600
0
–400
SAU
GEL
28
FEBRUARY 2000
1991 eruption
18
19
20
Time, in days
29
1
21
22
MARCH 2000
VOLCANO DEFORMATION–
Geodetic Monitoring Techniques
By Daniel Dzurisin
U.S. Geological Survey graphics