"CONFINED" AQUIFER
Undisturbed
water level
"WATER-TABLE" AQUIFER
1 meter water
level increase
1 microstrrain
contraction
Short periods of time
1 millimeter
water table rise
Still 1 microstrain
contraction
30% less
compressive stress
Long periods of time
VOLCANO DEFORMATION–Geodetic Monitoring Techniques
By Daniel Dzurisin
U.S. Geological Survey graphics