30 microradians,
1540–1625
50 micro
radians,
Level
1420–1455
10
Azimuth to
summit of Mount
St. Helens
Cup
42 microradians,
1625–1725
SOUTH
Level–Cup
0
10
70
1420
1500
30
1600
Eruption
EQ
EQ
EQ
EQ
60
Level–TLI
EQ
50
EQ
40
10
20
30
50
EQ
30
0
40
TLI up relative to Level
20
EQ
Tilt, in microradians
Cup up relative to Level
Meters
30
1700
30
Time, in hours and minutes on 10 April 1980
VOLCANO DEFORMATION–Geodetic Monitoring Techniques
By Daniel Dzurisin
U.S. Geological Survey graphics
1800
Tilt, in microradians
0
TLI