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Mapping without the sun
Zhang, Jixian

and seismic hazards (Wright, 2002; Biggs et al., 2007). InSAR
can map ground surface deformation immediately after an
earthquake (i.e., post-seismic deformation), which yields
important clues for inferring the properties of the Earth’s crust
and upper mantle (Figure lc) (Biggs et al., 2006). InSAR is
playing an increasingly important role in mapping triggered slip,
which occurs during an earthquake on faults not involved in the
main shock and is therefore extremely difficult to measure with
conventional technology (Fialko et al., 2002). In addition,
InSAR can identify blind faults from surface deformation
patterns. Combined with seismology and other geophysical and
geodetic measurements, InSAR can be expected to aid many
breakthroughs in understanding the entire phase of the
earthquake cycle (Wright, 2002).
2.2 Mapping volcanic deformation
SAR data acquired before and after a volcanic eruption can be
used to image the co-eruptive deformation. Surface deformation
data from InSAR can provide essential information about
(g) Westdahl
(h) Makushin
(i) Seguam
(j) Kiska
(f) Akutan
28.3 cm
(g) Westdahl
(h) Makushin \
(d) Korovin ' \ ^ •
J JjsV;
(f) Akutan
(e) Okmok
(b) Peulik.
(a) Augustine
(c) Aniakchak
Figure 2. InSAR deformation images of selected volcanoes in the Aleutian Islands, (a) InSAR image (1992-1993) of Augustine
Volcano that reveals deformation associated with compaction of 1986 pyroclastic flow deposits (Lu et al., 2003a). (b) InSAR
image (1996-1997) showing ~17 cm of episodic uplift of Peulik Volcano (Lu et al., 2002b). (c) An averaged InSAR image of
Aniakchak Volcano showing that the caldera subsided about 13 mm/yr from 1992 to 2002 (Kwoun et al., 2006). (d) InSAR
image of Korovin Volcano that shows more than 4 cm of inflation associated with the elevated seismicity from July to
September 2006. (e) Deformation interferogram of Okmok Volcano showing deflation of about 1.2 m associated with the 1997
eruption (Lu et al., 1998, 2000c, 2005a). (f) L-band JERS-1 InSAR image showing the complex deformation field at Akutan
Volcano that accompanied an intense earthquake swarm in March 1996 (Lu et al., 2000a, 2005b). (g) InSAR image showing
inflation of Westdahl Volcano, which occurred aseismically during 1993-1998 (Lu et al., 2000b, 2003d). (h) InSAR image of
Makushin Volcano showing about 7 cm of surface uplift associated with a possible eruption in January 1995 (Lu et al., 2002c).
(i) InSAR image of Seguam Volcano showing surface uplift of more than 6 cm during 1999-2000 (Lu et al., 2003a; Masterlark
and Lu, 2004). (j) InSAR image showing subsidence of Kiska Volcano due to a change in the hydrothermal system during
1999-2000 (Lu et al., 2002a). All interferograms are draped over DEM shaded relief images; areas without interferometric
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