Radar Interferometry
Measurement of Land
Subsidence in Phoenix,
Arizona
Results - Glendale /
Peoria / Sun City subsidence
In this radar image subset
over the cities of Glendale,
Peoria and Sun City, Luke
AFB is located to the
southwest with the
radiometrically-dark
aircraft runways trending
northeast-southwest.
The bright radar response to
the west corresponds to
agricultural fields and an
area of historical
subsidence. The
northern extent of the image
is generally undeveloped
with the Hedgpeth Hills,
Pyramid Peak and Deem Hills
mountains to the northeast.
Urban areas are identifiable
from the speckled radar
response from buildings and
fine dark lines
corresponding to major
streets. The urban
areas in the image include
Sun City immediately east of
the agricultural area,
Peoria to the northeast and
Glendale to the south.
Glendale geocoded
radar image
Several subsidence
features appear in the
three-year differential
interferogram. First,
there is a 15-km diameter
subsidence bowl spanning
Glendale, Peoria and Sun
City. Also, there is a
3-km diameter subsidence
bowl in Glendale.
Finally, there is an
apparent subsidence bowl
over the agriculture fields
which abruptly ends just
southeast of Luke AFB.
Glendale geocoded
differential interferogram
The east-west trending
line corresponds to Olive
Avenue and crosses through
the intense subsidence
feature in Glendale.
Profiles were extracted
along this line from the
3-year interferogram as well
as two other interferograms.
Glendale
interferogram profiles
The table summarizes the
interferometry measurements
at the intersection of 71st
Avenue and Olive Avenue,
near the center of the
Glendale subsidence bowl.
Signs of subsidence at this
intersection include several
cracks up to 3/8-inch in
adjacent cement residential
privacy walls. The
differences between
subsidence rates at this
intersection illustrate the
variability of subsidence
over time. For
example, considering the
vertical displacement and
dates spanned by the 688-day
and 1039-day interferograms,
it is noted that for the
351-day period from Aug 27,
1995 to Aug 12, 1996, the
71st/Olive subsidence rate
was 3.0 cm/year.
Interferogram
(dates and time
separation) |
Vertical
Displacement
(cm) |
SubsidenceRate
(cm/year) |
931008-950827,
688-day |
-11.9 |
6.3 |
931008-960812,
1039-day |
-14.8 |
5.2 |
950514-980223,
1016-day |
-21.9 |
7.9 |
Interferometry
measurements at 71st and
Olive Avenues
Damage associated with
subsidence at 71st and Olive
Avenues (courtesy David Meer)
Additional subsidence is
observed in north Scottsdale
and east Mesa and is
discussed in: Buckley,
Sean, Radar
Interferometry Measurement
of Land Subsidence, PhD
dissertation, The University
of Texas at Austin, 2000.