InSAR Error Analysis in Measuring Coseismic Deformation of 2008 ...

InSAR Error Analysis in Measuring 

Coseismic Deformation of 2008 

Damxung M w 6.3 Earthquake 

Zhang Jingfa Liu Bin and Lu Yi 

Institute of Crustal Dynamics, China Earthquake Administration 

100085, Beijing, China

CONTENTS 

Geological & Seismological Background 

Coseismic Deformation Measurement 

Error Analysis in InSAR Processing 

The Deformation Rates Time Series Analysis 

Conclusions

CONTENTS 





Conclusions

Geological & Seismological Features 

October 6, 2008, 

Damxung Earthquake 

The Mw6.3 earthquake, 

located: 90.3E, 29.8N (CENC), 

Depth: 8.0 km.

Geological & Seismological Features





CONTENTS 





Conclusions

CONTENTS 





Conclusions

Descending path 

Strip T176

Ascending path 

Strip T26

Numerical Simulation 

Surface deformation and stress 

distribution 

of the Dumxung earthquake 

(Ux: deformation of NS; Uy: WE; 

Uz: vertical; 

Sxx: normal stress of NS; 

Syy: WE;Sxy: shear)


Horizontal surface displacement of Dumxung earthquake. Left: Vertical 

displacement of co-seismic deformation(mm); Right:Post-seismic 

deformation rate 50 years after the earthquake(mm/a)


Vertical displacements. 

Left: co-seismic deformation 

(mm); 

Right: deformation rate after 

50 years (mm/a)

CONTENTS 





Conclusions

CONTENTS 





Conclusions

• The best result of Damxung Earthquake D- 

InSAR image was taken as standard, and some 

error factors will be studied according to this 

base image.

The main influence factors in InSAR processing 

Registration Error 

Unwrapping methods 

Atmospheric path delays 

Baseline error

Registration Error Between Master and Slave 

0 pixel deviation 

Interferogram Coherence


0.5 0 pixel deviation 





Registration of Master & Slave 

1.5 pixel deviation 






The relations between coherence and pixel deviations

Before deviating from the correct 

location about 1.5 pixels, there is a 

sine function between coherence 

and step, while exceeding 1.5 

pixels, the result will be unvalued.

Registration Error Between Master and DEM 

Original images 5 pixels deviation 10 pixels deviation

This is Registration Error Between Master 

and DEM, from this image, the 

deformation accuracy is related to 

registration error.

Comparison of different unwrapping methods 

network flow 

branch cut 

minimum discontinuity 

least-squares fringe tracking 

Conjugate Gradient

Comparison of different unwrapping methods 

comparative analysis of different unwraped methods

It is certainly that there is 

different influence degree 

in different unwrapping 

methods.

Topography correct atmospheric path delays 

Atmospheric path delays caused by topography 

Before correction 

After correction 

Descending path: 

T176


Ascending path:T026 

Before correction After correction

Atmospheric path delays caused by topography 

Before correction 


After correction 

Ascending path: 

WS T441 H/V

lhaz-GPS station 

Relations of GPS-PWV and MODIS-PWV 

Linear relationship between GPS-PWV 

and MODIS-PWV, the integration of two 

data can correct atmospheric path delay 

of InSAR! 

ncrs-GPS station

The relation between atmospheric path delays 

and topography in Damxung area, there is a 

linear function. 

That is, the path delays vary linearly with height 

as a first-order approximation.

Effects of baseline refinement 

T176

Effects of baseline refinement 

T26

The effect of baseline refinement is clear.

Baseline deviation -3m 

2 专题研究内容 ----理论研究 

Baseline is OK 

Baseline deviation +3m

Baseline deviation -3m 


Baseline is OK 

Baseline deviation +3m


0.2 

0.15 

0.1 

0.05 

0 

-0.05 

-0.1 

-0.15 

-0.2 

-3 -2 -1 0 1 2 3 

C点 

A点 

B点

The baseline error will reduce the range 

of deformation field

CONTENTS 





Conclusions

CONTENTS 





Conclusions

The Deformation Rates Time 

Series Analysis 

Time series analysis before the earthquake 

Time series analysis after the earthquake


Unwraped images of PS points Orbital contribution 

DEM error 

Time series of deformation signal 

Atmospheric contribution

Time series analysis before the earthquake


PS-InSAR Time series 

of deformation signals 

SBAS-InSAR Time series 

of deformation signals


PS InSAR SBAS InSAR


PS InSAR


Standard deviations of the selected points 

in 8 areas 

区域 A 

区域 B 

区域 C 

区域 D 

区域 E 

区域 F 

区域 G 

区域 H 

Lon Lat 

mean_v 

(mm/year) 

90.482 30.075 -6.74 0.61 

90.488 30.072 -7.78 0.76 

90.314 30.059 3.00 0.75 

90.310 30.059 2.33 0.69 

90.446 30.101 2.53 0.75 

90.464 30.121 3.30 0.72 

90.394 29.875 2.05 0.66 

90.384 29.887 1.63 0.53 

90.325 29.936 -1.04 0.49 

90.314 29.952 -1.73 0.45 

90.252 30.165 -3.82 1.62 

90.313 30.121 -1.92 1.15 

90.575 29.975 -4.21 1.5 

90.598 29.980 -3.93 1.44 

90.207 29.995 2.3 1.48 

90.201 29.994 3.16 1.48 

Std 

(mm/year)


SBAS InSAR


Standard deviations of the selected points in 8 

areas 

区域 A 

区域 B 

区域 C 

区域 D 

区域 E 

区域 F 

区域 G 

区域 H 

Lon Lat 

mean_v 

(mm/year) 

Std 

(mm/year) 

90.487 30.072 -7.20 0.62 

90.485 30.071 -7.23 0.65 

90.317 30.059 2.06 0.43 

90.317 30.06 2.28 0.29 

90.463 30.127 3.64 0.66 

90.464 30.125 3.15 0.54 

90.387 29.876 1.84 0.41 

90.381 29.881 2.21 0.45 

90.312 29.930 -1.11 0.33 

90.31 29.934 -0.98 0.32 

90.31 30.121 -6.08 0.6 

90.296 30.134 -5.93 0.82 

90.574 30.15 -4.21 0.86 

90.577 30.076 -2.07 0.78 

90.209 29.986 2.21 0.76 

90.217 29.984 3.68 0.85

The deformation rates from SBAS-InSAR and PS- 

InSAR time series analysis are consistent with 

each other. 

Obviously, the velocity in the edge of the basin 

is bigger than the place in the flat area. 

The maximum upward velocity reached 

3.1mm/year (LOS) and the maximum downward 

velocity reached -7.4mm/year (LOS).

In the north of the basin, there is an area of 

great downward trend. The reason is that 

there is one big geothermic plant and the 

pumping of the geothermic cause the great 

ground subsidence


去噪后年形变速率(LOS) 

PS-meanv SBAS-meanv


PS mean_v lines plot


SBAS mean_v lines plots


The activities of faults in Yangbajing Basin 

A: -5~-8mm/a 

B:3~5mm/a 

C:-1.5~2.0mm/a

Time series analysis after the earthquake 

Damxung 

earthquake

Because of the impact of the 

aftershocks, in epicenter of 

Damxung, there is still ground 

subsidence.

CONTENTS 





Conclusions

CONTENTS 





Conclusions

Conclusions 

1. The major perturbing factors limiting D-InSAR accuracy 

is as follows: 

(a)Registration between master image to slave; 

(b)Orbit Error; 

(c)Atmospheric propagation delay.

Conclusions 

2. The velocity in the edge of the basin is bigger than the 

place in the flat area. 

In the epicenter of Damxung, there is still ground 

subsidence in a long time after the earthquake.

InSAR Error Analysis in Measuring Coseismic Deformation of 2008 ...

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