Karakterisasi Letusan Merapi menggunakan Data SAR (Synthetic
Aperture Radar)
Saepuloh et al., (2013), Interpretation of ground surface changes prior to the 2010 large eruption of Merapi volcano using ALOS/PALSAR, ASTER TIR and gas emission data, Journal of Volcanology and Geothermal Research, Vol. 261, pp. 130-143.
Saepuloh et al., (2010), SAR- and gravity change-based characterization of the distribution pattern of pyroclastic flow deposits at Mt. Merapi during the past ten years, Bulletin of Volcanology, Vol. 72, No. 2, pp. 221-232.
Asep Saepuloh, Dr. Eng. FITB, ITB
Content
1. An overview of Mt. Merapi Eruption 1996-2006
2. ALOS/PALSAR Observed 2010 Eruption
3. Eruption precursor using time series of D-InSAR
and ASTER TIR
Interaction of Microwave Signal to Surface
ππ = ππ π0π΄πΊ2π2
4π 3π 4
The radar equation
Dielectric permittivity
Incident angle
Roughness funct.
Ο0 = 4π4β02cos4ππ πΌ 2π
Ξ±ββ =ππ β 1 ππππ β sin2 ππ + ππ sin2 ππ + ππ
2 ππ β 1
Ο ππ cos ππ + ππππ β sin2 ππ
4
Ξ±π£π£ =ππ β 1 ππππ β sin2 ππ + ππ sin2 ππ + ππ
2 ππ β 1
Ο ππ cos ππ + ππππ β sin2 ππ
4
Magnetic permeability
Sm
all
Per
turb
atio
n M
odel
β’ The Synthetic Aperture Radar (SAR) data were used.
β’ The superiority of SAR data means that they can provide periodic Earth observations regardless of the time or weather.
Study area
http://www.stanford.edu/
1. An Overview of the Last Decade of Mt. Merapi Eruption
β’ Ground check
- Geological observation - Rock sampling collection
Objectives and Data Used
Data used:
1. JERS-1
2. RADARSAT-1
Advantage: Sun-synchronous orbit with moderate incidence angle (39ΒΊ-37ΒΊ)
Limitation: Ten years observation covering four times of eruption (1996-2006)
JERS-1
RADARSAT-1
CSA
Objectives:
Detect and characterize the
pyroclastic flow deposits (P-
zone) each eruption period
Temporal SAR Data
Pair selection of SAR data to detect pyroclastic flow deposits with each eruption. A black triangle denotes a major eruption. A period of high
seismic activity is shown by a gray bar.
Intensity images of JERS-1 and RADARSAT-1 SAR data around Mt.
Merapi at a descending mode.
The P-zones are detected by comparing the two SAR data before and after events.
The two data with same path and raw reduce the geometrical error.
te-1
te+1
P-zone
te
Temporal Pattern Analysis of the P-zones
Schematic of the P-zone Parameters: A= Distribution area = Perimeter, D= Flow distance Ξ±= Included angle
Ξ³= Collapse direction
Each selected pair is used to detect P-zone.
Then, the parameters of each detected P-zone are calculated and analyzed.
Temporal change of P-zones extracted from seven SAR data pairs. Thin arrows stand for
collapse directions of each P-zone.
Overlay of seven P-zones to highlight the temporal change of
distribution pattern.
2. ALOS/PALSAR Observed 2010 Eruption
Advanced Land Observing Satellite
Communication antenna
Solar Paddle PALSAR
PRISM
AVNIR-2
Item Specification1270 MHz / 23.6 cm
Chirp band width
Image modes
Single polarization (HH or VV)
Dual pol. (HH+HV or VV+VH)
Quad-pol. (HH+HV+VH+VV)
Off-nadir angle
Variable: 9.9 β 50.8 deg.
(inc. angle range: 7.9 - 60.0)
Look direction Right
Yaw steering ON
Swath width
70 km (single/dual [email protected]Β°)
30 km ([email protected]Β°)
Ground resolution~ 9 m x 10 m (single [email protected]Β°)
~ 19 m x 10 m (dual [email protected]Β°)
~ 30 x 10 m ([email protected]Β°)
~ 71-157m (4 look) x 100m (2 look)
Data rates
Orbit cycle 46 days
Centre frequency
28 MHz (single polarisation)
14 MHz (dual, quad-pol., ScanSAR)
ScanSAR (HH or VV; 3/4/5-beam)
ScanSAR: 20.1-36.5 (inc. 18.0-43.3)
350 km (ScanSAR 5-beam)
Rg (1 look) x Az (2 looks)
240 Mbps (single/dual/quad-pol)
120 or 240 Mbps (ScanSAR)
Mission:
To provide maps for Japan and other countries including those in the Asian-Pacific region (Cartography). To perform regional observation for "sustainable development", harmonization between Earth environment and development (Regional Observation). To conduct disaster monitoring around the world (Disaster Monitoring). To survey natural resources (Resources Surveying). To develop technology necessary for future Earth observing satellite (Technology Development).
Backscattering Intensity Before and After Eruption
2007.9.12
2010.11.15
Extracted Pyroclastic Flow
Deposits
Pyroclastic Flow Deposits 1996-2010
The eruption of Mt. Merapi in November 2010 has a different characteristic in comparison with the last decade of eruption. The coverage area of the
pyroclastic flow deposits is about 7 times larger than the eruption in 2006.
3. Eruption precursor using time series of ALOS/PALSAR and ASTER TIR
Three point of view:
A. Deformation
B. Lava dome shape
C. Surface thermal
D. EDM measurement
A. Deformation
23 data pairs with short temporal baseline were used to generate interferograms.
Pair
Acquisition Time Baseline
Path/Row Off nadir
angle Mode
1st 2nd Perpendicular
(m)
Temporal
(days)
1 2007/6/8 2006/12/6 2598 184 431/703 34.3 Ascending
2 2007/9/8 2007/1/21 979 230 431/703 34.3 Ascending
3 2007/10/24 2007/6/8 344 138 431/703 34.3 Ascending
4 2007/12/9 2007/9/8 140 92 431/703 34.3 Ascending
5 2008/1/24 2007/10/24 180 92 431/703 34.3 Ascending
6 2008/3/10 2007/12/9 188 92 431/703 34.3 Ascending
7 2008/4/25 2008/1/24 172 92 431/703 34.3 Ascending
8 2008/6/10 2008/3/10 553 92 431/703 34.3 Ascending
9 2008/7/26 2008/4/25 162 92 431/703 34.3 Ascending
10 2008/9/10 2008/6/10 78 92 431/703 34.3 Ascending
11 2008/10/26 2008/7/26 742 92 431/703 34.3 Ascending
12 2008/12/11 2008/9/10 109 92 431/703 34.3 Ascending
13 2009/1/26 2008/10/26 32 92 431/703 34.3 Ascending
14 2009/6/13 2008/12/11 292 184 431/703 34.3 Ascending
15 2009/10/29 2009/1/26 432 276 431/703 34.3 Ascending
16 2009/12/14 2009/6/13 56 184 431/703 34.3 Ascending
17 2010/1/29 2009/10/29 141 92 431/703 34.3 Ascending
18 2010/3/16 2009/12/14 216 92 431/703 34.3 Ascending
19 2010/6/16 2010/1/29 342 138 431/703 34.3 Ascending
20 2010/9/16 2010/3/16 218 184 431/703 34.3 Ascending
21 2010/11/1 2010/6/16 329 138 431/703 34.3 Ascending
22 2010/12/17 2010/9/16 96 92 431/703 34.3 Ascending
23 2011/2/1 2010/11/1 36 92 431/703 34.3 Ascending
Improvement of perpendicular baseline
Local Limitation of InSAR ALOS/PALSAR
Ascending and descending pairs are limited
Need assumption to obtain three displacement component
No GPS measurement since 2006 up to 2010
High tropospheric disturbance
Meteorological measurement is not available
Large amount of interferogram is required
Deformation is not constant over time
Need advanced method to separate the deformation and tropospheric effect
A. Deformation
Pair-wise Logic
Pair-wise logic method (Massonnet and Feigl, 1995) was
applied to the 24 pair data to reduce the atmospheric phase
delay from atmosphere.
The two interferograms with shared data were paired.
The atmospheric signal during that acquisition will
contaminate the displacement signal in both interferograms.
The addition of both interferograms caused doubled
deformation signal and removed the atmospheric signal
(Hanssen, 2001).
A. Deformation
Pair-wise Logic
P-16
date 1- date 2
S-16
date 1- date 3
+ +
-
-
P-17
date 2- date 3
- -
+
+
Unwrapped Interferograms 2006-2010 after pair-wise logic applied
Inflation in 2008 and 2010
The deformation do not follow the topographical pattern: low contribution of tropospheric delay.
Inflation 2008
EDM : ~10 mm/day
InSAR: ~1.5 mm/day
Inflation 2010
InSAR : ~3 mm/day
The fringes discontinuity indicated the distribution of the new volcanic products at early eruption stage.
The inflation signal was detected in 2008 and the eastern flank shows the deformation
highly toward satellites in 2010.
2008
2010
LOS
GPS results show strong deformation especially at the eastern from the summit about 20 cm. Two arc-lines are local normal fault. The deformation signal follows the local fault system.
Early Field Deformation Measurement
(Subandriyo et. al., 2006)
GPS and EDM measurement in 2006
LOS deformation in 2010
B. Dome Shape
The seed fill method (Revol and Jourlin, 1997) was applied
to detect surface changes of lava dome
The backscattering intensity data between 2006 and 2010
were used
The seed fill method defines a simplest single linkage scheme
such that the pixelβs seed P and neighborhood pixel P' are
considered as related β if their gray levels f(P) and f(P') are
under threshold value Ξ± and connected to eight neighborhood
pixel β8 as follows:
Seed-fill method
π β πβ² = π‘ππ’π, ππ π π β π πβ² β€ πΌ β β8= 1
ππππ π, ππ‘βπππ€ππ π
B. Dome Shape Seed fill time table
IKONOS image of lava dome on May 10th, 2006 was used as one of references for the βseedβ location
(Bulletin of Global Volcanism Program BGVN 32:02)
No Acquisition
Time
Off nadir
angle Mode
D-1 2007/6/8 34.3 Ascending
D-2 2007/9/8 34.3 Ascending
D-3 2007/12/9 34.3 Ascending
D-4 2008/1/24 34.3 Ascending
D-5 2008/4/25 34.3 Ascending
D-6 2008/6/10 34.3 Ascending
D-7 2008/9/10 34.3 Ascending
D-8 2008/10/26 34.3 Ascending
D-9 2008/12/11 34.3 Ascending
D-10 2009/1/26 34.3 Ascending
D-11 2009/10/29 34.3 Ascending
D-12 2009/12/14 34.3 Ascending
D-13 2010/3/16 34.3 Ascending
D-14 2010/6/16 34.3 Ascending
D-15 2010/9/16 34.3 Ascending
D-16 2010/11/1 34.3 Ascending
D-17 2010/12/17 34.3 Ascending
D-18 2011/2/1 34.3 Ascending
B. Dome Shape Seed fill in red portions
Roughness changes of the lava dome prior to the 2010 eruption
2010.09.16 2010.11.01
Ο0 = 4π4β02cos4ππ πΌ 2π
Considering time series, the surface Roughness is remaining
C. Surface Thermal
The 30 scenes of ASTER TIR
data during nighttime and 2
scenes during daytime
observations were used.
The surface temperature T can
be extracted from thermal
radiance as follows:
π =2πβπ2
πlnππβππβ5
ππ π+ 1
No Date Time Path/Row
T-1 2006/9/3 15:10:30 UT 230/489
T-2 2006/9/10 15:16:37 UT 231/489
T-3 2006/9/19 15:10:21 UT 230/489
T-4 2006/10/12 15:16:15 UT 231/489
T-5 2006/11/29 15:16:26 UT 231/489
T-6 2007/5/24 15:16:50 UT 231/489
T-7 2007/7/4 15:11:00 UT 230/489
T-8 2007/8/28 15:17:19 UT 231/489
T-9 2007/9/6 15:11:06 UT 230/489
T-10 2008/1/26 03:05:45 UT 120/182
T-11 2008/5/26 15:17:23 UT 231/489
T-12 2008/6/4 15:11:14 UT 230/489
T-13 2008/6/20 15:11:15 UT 230/489
T-14 2008/7/6 15:11:14 UT 230/489
T-15 2008/9/15 15:17:23 UT 231/489
T-16 2008/9/24 15:11:11 UT 230/489
T-17 2009/1/21 15:17:54 UT 231/489
T-18 2009/5/13 15:17:57 UT 231/489
T-19 2009/6/14 15:17:38 UT 231/489
T-20 2009/6/23 15:11:20 UT 230/489
T-21 2009/6/30 15:17:24 UT 231/489
T-22 2009/8/1 15:17:18 UT 231/489
T-23 2009/8/10 15:11:07 UT 230/489
T-24 2009/8/17 15:17:17 UT 231/489
T-25 2009/9/27 15:10:54 UT 230/489
T-26 2009/11/5 15:17:11 UT 231/489
T-27 2010/7/19 15:16:57 UT 231/489
T-28 2010/8/20 15:16:46 UT 231/489
T-29 2010/8/29 15:10:37 UT 230/489
T-30 2010/9/14 15:10:38 UT 230/489
T-31 2010/11/1 15:10:27 UT 230/489
T-32 2010/11/15 03:05:20 UT 120/182
AS
TE
R T
IR t
ime
table
ASTER Image Database for Volcanoes
http://igg01.gsj.jp/vsidb/image/Merapi/aster_p1.html
C. Surface Thermal
The hot spots around the summit as an indicator of thermal activity.
The radiance of hot volcanic products termed as hot spots saturates the TIR detector.
The ASTER TIR band 13 was assigned to calculate surface temperature from thermal radiance data.
The criterion of band selection is based on the highest absolute accuracy (β€1 K) and the highest radiometric resolution of measured value (0.23 K) among TIR bands (Fujisada et al., 1998).
The least affected by any atmospheric characteristics (Vaughan et al., 2010).
2006.11 2008.01
2010.11
Location of six available Electronic Distance Measurement (EDM)
arround the summit of Mt. Merapi.
Three stations from six reflectors were used:
RK: 2007.1.5~2010.10.26
RB: 2009.4.4~2010.10.26
RJ: 2010.4.1~2010.10.25
The measurement frequency is once per day in average.
The changes of the distance is the objective of the measurement.
D. EDM measurement
RK reflectors:
High attenuation in 2008 and 2010
D. EDM measurement
-1 m/yr -0.1 m/yr
-1.2 m/yr +0.1 m/yr
RB reflectors:
Shortening distance at January 2010
RJ reflectors:
Increasing distance prior to the peak eruption
The LOS Displacement Rate
The Line of Sight (LOS) displacement rate from InSAR at six locations shows that the significant uplifting occurs five times from 2007 to 2010.
A B
C
The Lava Dome Changes
The coverage area of the D-zones supposed to be the growth of the lava dome fractures as detected by ALOS/PALSAR and CO2 gas volume prior to
the eruption at the summit.
The Surface Temperature
The Line of Sight (LOS) displacement rate from InSAR at six locations shows that the significant uplifting occurs five times from 2007 to 2010.
W E
W E
InS
AR
mea
sure
men
t
Shaded map
Four region of volcanic system (Scandone et al., 2007): the Supply, Storage, Transport, and Eruptive system.
The four systems are sufficient for configuration of magmatic system at Mt. Merapi.
The Supply system serves as deep reservoir which is located in about 8.5 km depth (Beauducel and Cornet, 1999).
The Storage system serves as shallow reservoir which is located in about 2-3 km depth (Ratdomopurbo and Poupinet, 2000)
Interpretation
C B C
Conceptual model (Saepuloh et al., 2010 Bull. Volcanol)
Acceleration Rate
C B A
Temporal cross-section from the summit (distance=0) to the NE flank shows different acceleration of deformation supposed to be the flumes prior to the eruption.
Need 2 years optimum
pressure β dome failure..(?)
Deformation Precursor The inflation phenomena might
indicate the pulsatory magma ascent in which individual magma batches detached from the Supply system (Gardner et al., 1998).
The eruptive system probably connected with storage system due to high pressurized magma after the barrier system reached the maximum pressure limit.
2008
2010
The magma batch detached from the deep reservoir and stored in 2.6 km depth.
Penelitian Berjalan: Pendeteksian rekahan beresolusi tinggi dengan data SAR
Range
Depression angle
Ascending Orbit Descending Orbit
Weak
Radar
ground
range
image
o Dual SAR observation
were used: Ascending
satelite heading from South
toward North and
Descending in vice versa.
o Provide surface
information in two look
directions for the same
object.
Strong Strong
Backscattering Intensities before Eruption
The Summit
Yogyakarta 5 km
N The Summit
Yogyakarta 5 km
N
pal_091029asc pal_090807des
Backscattering intensities data before eruption in Ascending
(left) and Descending (right) show the ground surface in two
different angles of view.
LFD before Eruption
The Summit
Yogyakarta 5 km
N The Summit
Yogyakarta 5 km
N
pal_091029asc pal_090807des
Linear Features Density (LFD) map before eruption in
Ascending (left) and Descending (right) related to the density
of faults and/or fractures.
Backscattering Intensities after Eruption
The Summit
Yogyakarta 5 km
N The Summit
Yogyakarta 5 km
N
pal_110201asc pal_101105des
Backscattering intensities data after eruption in Ascending
(left) and Descending (right) show the ground surface
including new pyroclastic flow deposits.
P-Zone P-Zone
LFD after Eruption
The Summit
Yogyakarta 5 km
N The Summit
Yogyakarta 5 km
N
pal_110201asc pal_101105des
Linear Features Density (LFD) map after eruption in
Ascending (left) and Descending (right) related to the density
of faults and/or fractures.
Tota LFD Before and After Eruption
The Summit
Yogyakarta 5 km
N
Before After
The Summit
Yogyakarta 5 km
N
Total Linear Features Density (LFD) map after and before
eruptions shows the increment of fraulted and/or fractured
zones.