300
ρ=
2.7 g/cm3
Gravity change, ∆g, in microgals
250
200
150
100
50
0
–50
–100
November–December 1975
∆g = –1.75 ∆h – 9.2
December–April 1977
∆g = –6.07 ∆h + 33.6
April–October 1977
∆g = –2.80 ∆h – 7.2
–1600
–1200
–800
–400
0
Height change, ∆h, in centimeters
VOLCANO DEFORMATION–Geodetic Monitoring Techniques
By Daniel Dzurisin
U.S. Geological Survey graphics
400