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RADARSAT-1
& 2
SAR-
advantage &
Disadvantage
SAR APPLICATION IN
GEOLOGY
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Geological structure mapping
Lineament mapping
Geomorphological mapping
Surficial material assessment
Surficial bedrock mapping
Sedimentology mapping
Landslide hazard assessment
USEFUL IN .
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RADARSAT 1
Radarsat-1 launched in 1995
operates in C-band
synthetic aperture radar (SAR)
operates in 7 beam position modes
able to steer it beams from 10 to 60
incidence angle
resolution from 8 to 100m
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RADARSAT-1
Beam Mode Position
incidence angle)
Resolution m) Area km)
Fine 15 8 50 x 50
Standard 7 25 100 x 100
Wide 4 30 165 x 165
Extended High 6 25 75 x 75
Extended Low 1 35 170 x 170
ScanSAR Narrow 2 50 300 x 300
ScanSar Wide 1 100 500 x 500
Radarsat International. n.d. Radarsat Geology Handbook
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RADARSAT-1
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RADARSAT-1
Standard mode ScanSAR Wide
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LITHOLOGY AND STRUCTURE
The finer siltstone particles produce a darker return, while the coarser
limestone particles produce a brighter backscatter return attributed
to the increased surface roughness (Standard beam).
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GEOMORPHOLOGICAL/LANDFORM/
STRUCTURE MAPPING
The Treetop Geology concept is
illustrated in this RADARSAT image
of a dense tropical forest. An eroded,
sedimentary dome structure is
clearly evident (Fine beam)
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LANDSLIDE HAZARD ASSESSMENT
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CONDITIONS INFLUENCING GEOLOGICAL
MAPPING
Geological
activity
Radar response Beam mode Incidence angle
Geological
structure mapping
topographic relief fine and standard for
detailed mapping
Wide and ScanSAR forbasin wide mapping
shallow angle by
enhancing
topography shadowIntermediate angle
for high relief terrain
Lineament topographic relief fine and standard for
detailed identification
Wide and ScanSAR for
regional identification
shallow angle to
enhance topographic
relief
Geomorphological/
landform
topographic relief fine and standard for
detailed identification
Wide and ScanSAR for
regional identification
shallow angle to
enhance subtle
terrain through
shadowing
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CONDITIONS INFLUENCING GEOLOGICAL
MAPPING
Geological
activity
Radar response Beam mode Incidence angle
Surficial material
assessment
unique
backscatter in
response to
different soilroughness & soil
moisture
fine and standard for
detailed identification
Wide and ScanSAR for
regional identification
soil moisture (steep
angle)
soil roughness
(shallow angle)
Surficial bedrock
mapping
unique
backscatter due
to fracture pattern
in different rocks,rock fabric,
texture and
mineral
composition
fine and standard for
detailed identification
Wide and ScanSAR for
regional identification Better with low moisture
level (backscatter
correlated closely with
surface rougness)
shallow angle to
maximize the contrast
in backscatter
resulting in varyingsurface roughness
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CONDITIONS INFLUENCING GEOLOGICAL
MAPPING
Geological activity Radar response Beam mode Incidence angle
Sedimentology
mapping
unique
backscatter in
response to
different soil
roughness & soilmoisture
Topographic relief
Erosional pattern
fine and standard for
detailed identification
Wide and ScanSAR for
regional identification
Steep angle (soil
moisture)
Shallow angle (soil
roughness)
Landslide hazard
assessment
Surface roughness
Landslide
deposited area
Change in
vegetation pattern
fine and standard for
detailed identification
Shallow angle
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Speckle Filtering
LINEAMENT MAPPING
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Stages in despeckle
LINEAMENT MAPPING (CONT )
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Lineament filter
a) Directional
b) Non-directional
LINEAMENT MAPPING (CONT )
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LINEAMENT MAPPING (CONT )
Lineament
Lineament
Lineament
Important in
Determination of
groundwater source
Landslide
Mineral potential area
Geological structure
studies
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Used for mapping ground changes and infrastructure damages
Calculating the ratio differences in terms of backscatter
intensity based on multitemporal images
The drawback is
significant variability of backscatter that depends on theincidence angle when the image is required. The sensor must
acquire the image at the same incidence angle before the
earthquake happen so that the backscatter intensity can be
quantified.
The concept when assessing damages due to an earthquake
due to side-looking acquisition geometry, urban constructions
often produce distinct signal caused by double bounce
mechnanism, this pattern changes when the buildings are
damaged by an earthquake
EARTHQUAKE STUDIES
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Used for mapping volcanic deformations
Useful in times of eruptions where there is a lot of smoke
obscuring visibility
Technique: calculating a dif ference of intensity images from
before and after the event. For example, lahar and pyroclasticflow
Drawback: certain band (C- & L- bands) are not clearly show
changes of backscatter intensity
VOLCANIC ACTIVITY
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Useful for storm-induce landsliding where cloud cover
impeded the use of optical sensor
However, due to better resolution and capability of multiband
manipulation, optical data is still preferable than SAR
Drawback:
a) layover and shadowing effect in high slopes area.
b) Different viewing position will affect the backscatter
intensity quantification
c) Not much distinct backscatters from the images taken
before and after an event due to the size of landslides and
also if the background is the same with the landslides (bare
ground)
LANDSLIDES
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Ideal sensor for flood studies due to backscatter signature of
water is so distinct compare to the background
Floodwater remain visible for longer time
Delineation of flood boundary can be done due to flood
receding slowly
Water appear darker in SAR image
SAR able to detect flood under canopy area
However, experience researcher is needed to interpret the
backscatter data under the canopy and image before and
after a flood event are needed for comparison
FLOODING