îophysical and 
1 to aid many 
)hase of the 
-uption can be 
:e deformation 
mation about 
' Augustine 
(b) InSAR 
R image of 
(d) InSAR 
3m July to 
th the 1997 
l at Akutan 
ie showing 
R image of 
ah, 2002c). 
Masterlark 
tem during 
rferometric 
magma dynamics (Lu, 2007; Lu et al., 2007b). In addition, 
InSAR can be used to map the deformation of volcanoes during 
quiescent periods. InSAR-derived surface deformation patterns 
provide important insight into the structure, plumbing, and state 
of restless volcanoes and can be the first sign of increasing 
levels of volcanic activity preceding swarms of earthquakes or 
other precursors that signal impending intrusions or eruptions. 
For example, Lu et al. (2007b) used InSAR images from ERS-1, 
ERS-2, JERS-1, Radarat-1, and Envisat satellites to study 
ground surface deformation associated with a variety of 
volcanic processes, including volcanic inflation and magma 
intrusion, preceding seismic swarms at several active and non 
active Aleutian volcanoes, persistent volcano-wide subsidence 
at calderas that erupted several hundred years ago, magmatic 
intrusion and associated tectonic stress release at active 
volcanoes, subsidence caused by a decrease in pore fluid 
pressure in active hydrothermal systems, and a lack of expected 
deformation associated with recent eruptions at the most active 
volcanoes. The spatial distribution of surface deformation data 
derived from InSAR images enables the construction of detailed 
mechanical models to enhance the study of magmatic processes. 
Systematic mapping of volcanic deformation along major plate 
boundaries can provide a basis for improved modeling and a 
better understanding of magmatic plumbing systems. 
2,3 Mapping land surface deformation associated with fluid 
withdrawal 
Surface subsidence and uplift that are related to the extraction 
and injection of fluids in groundwater aquifers and petroleum 
reservoirs can be seen in InSAR images (Figure 3a). InSAR- 
based surface deformation mapping can provide fundamental 
data on reservoir/aquifer properties and processes and improve 
the ability to assess and mitigate adverse consequences (Lu and 
Danskin, 2001). InSAR can be also used to map the movement 
of landslides, providing a new tool for landslide monitoring 
(Figure 3b). 
Figure 3. (a) Deformation of Suzhou over southeastern China from L-band (wavelength = 24 cm) JERS-1 InSAR imagery. 
Subsidence of more than 10 cm/year during 1992 and 1996 can be interfered from the multiple temporally averaged InSAR 
image, (b) Deformation of the Slumgullion landslide, Colorado, USA, mapped from a fine-beam Radarsat-1 image. Maximum 
displacement could reach more than 10 cm in 24 days.