FRACTURE-NORMAL STRAIN
Up to 200 cm
water-level
rise (8 feet)
FRACTURE-PARALLEL STRAIN
Undisturbed
water level
No detectable
water-level
change
1 microstrain
contraction
Maximum pressure change for
stress normal to fractures
Minimal pressure change for
Figure 3.1.2
stress parallel to fractures
VOLCANO DEFORMATION–Geodetic Monitoring Techniques
By Daniel Dzurisin
U.S. Geological Survey graphics