Nanostrain
-100
-500
-700
16:00 10
Nanostrain / min
A
BUR STRAIN
-300
20
30
40
0
50 17:00 10
20
30
40
50 18:00
B
BUR STRAIN - RATE
-5
x 25
Eruption
-10
-15
16:00 10
20
30
40
50 17:00 10
20
30
40
50 18:00
17 JANUARY 1991
Time, hours
VOLCANO DEFORMATION–
Geodetic Monitoring Techniques
By Daniel Dzurisin
U.S. Geological Survey graphics