TY - JOUR
T1 - Local interpolation of coseismic displacements measured by inSAR
AU - Yaseen, M.
AU - Hamm, N. A.S.
AU - Woldai, T.
AU - Tolpekin, V. A.
AU - Stein, A.
N1 - Funding Information:
The authors gratefully thank the Higher Education Commission (HEC) of Pakistan for providing funds for this research. We thank the European Space Agency for offering Envisat ASAR Images of the Bam region. We also acknowledge Dr. Simone Atzori (INGV, Rome) for helping us with programming of the inversion modeling. We thank Dr. Mark van der Meijde and Dr. H.M.A. van der Werff (ITC) for kindly providing guidance for the initial InSAR processing of the data. Thanks also to Ms. Salma Anwar and Saleem Ullah for their valuable suggestions and comments during the study.
PY - 2013
Y1 - 2013
N2 - Coseismic displacements play a significant role in characterizing earthquake causative faults and understanding earthquake dynamics. They are typically measured from InSAR using pre- and post-earthquake images. The displacement map produced by InSAR may contain missing coseismic values due to the decorrelation of ASAR images. This study focused on interpolating missing values in the coseismic displacement map of the 2003 Bam earthquake using geostatistics with the aim of running a slip distribution model. The gaps were grouped into 23 patches. Variograms of the patches showed that the displacement data were spatially correlated. The variogram prepared for ordinary kriging (OK) indicated the presence of a trend and thus justified the use of universal kriging (UK). Accuracy assessment was performed in 3 ways. First, 11 patches of equal size and with an equal number of missing values generated artificially, were kriged and validated. Second, the four selected patches results were validated after shifting them to new locations without missing values and comparing them with the observed values. Finally, cross validation was performed for both types of patch at the original and shifted locations. UK results werebetter than OK in terms of kriging variance, mean error (ME) and root mean square error (RMSE). For both OK and UK, only 4 out of 23 patches (1, 5, 11 and 21) showed ME and RMSE values that were substantially larger than for the other patches. The accuracy assessment results were found to be satisfactory with ME and RMSE values close to zero. InSAR data inversion demonstrated the usefulness of interpolation of the missing coseismic values by improving a slip distribution model. It is therefore concluded that kriging serves as an effective tool for interpolating the missing values on a coseismic displacement map.
AB - Coseismic displacements play a significant role in characterizing earthquake causative faults and understanding earthquake dynamics. They are typically measured from InSAR using pre- and post-earthquake images. The displacement map produced by InSAR may contain missing coseismic values due to the decorrelation of ASAR images. This study focused on interpolating missing values in the coseismic displacement map of the 2003 Bam earthquake using geostatistics with the aim of running a slip distribution model. The gaps were grouped into 23 patches. Variograms of the patches showed that the displacement data were spatially correlated. The variogram prepared for ordinary kriging (OK) indicated the presence of a trend and thus justified the use of universal kriging (UK). Accuracy assessment was performed in 3 ways. First, 11 patches of equal size and with an equal number of missing values generated artificially, were kriged and validated. Second, the four selected patches results were validated after shifting them to new locations without missing values and comparing them with the observed values. Finally, cross validation was performed for both types of patch at the original and shifted locations. UK results werebetter than OK in terms of kriging variance, mean error (ME) and root mean square error (RMSE). For both OK and UK, only 4 out of 23 patches (1, 5, 11 and 21) showed ME and RMSE values that were substantially larger than for the other patches. The accuracy assessment results were found to be satisfactory with ME and RMSE values close to zero. InSAR data inversion demonstrated the usefulness of interpolation of the missing coseismic values by improving a slip distribution model. It is therefore concluded that kriging serves as an effective tool for interpolating the missing values on a coseismic displacement map.
KW - Coseismic displacements
KW - Earthquakes
KW - Geostatistics
KW - InSAR
KW - Kriging
UR - http://www.scopus.com/inward/record.url?scp=84880287648&partnerID=8YFLogxK
U2 - 10.1016/j.jag.2012.12.002
DO - 10.1016/j.jag.2012.12.002
M3 - Article
AN - SCOPUS:84880287648
SN - 1569-8432
VL - 23
SP - 1
EP - 17
JO - International Journal of Applied Earth Observation and Geoinformation
JF - International Journal of Applied Earth Observation and Geoinformation
IS - 1
ER -