ARIA InSAR displacement maps (interferograms) 

Displacement maps from Sentinel-1 track 131, acquired on 2020/10/30

The Advanced Rapid Imaging and Analysis (ARIA) team at NASA's Jet Propulsion Laboratory and California Institute of Technology, both in Pasadena, California, created this displacement map with measurements of the surface displacements, in the radar line-of-sight, caused by the recent Mw 7.0 (October 30, 2020) earthquake beneath the Aegean Sea between Samos, Greece and Izmir, Turkey. The map was derived from synthetic aperture radar (SAR) images from the Copernicus Sentinel-1 satellites, operated by the European Space Agency (ESA). The team computed the interferometric difference (interferogram or interferometric SAR) between the post-event image acquired on October 30, 2020 with a pre-event image acquired on October 24, 2020, on the Sentinel-1 ascending (satellite moving north) track 131. The interferometric SAR (InSAR) measures the component of surface displacement in the line-of-sight (LOS) between the ground and the satellite, which is at an angle of about 40 degrees from the vertical and slightly south of due west. The western part of Samos island moved up to 10 cm upward and a small area of the north coast of Samos moved downward by up to 10 cm.

Each pixel measures about 90 meters across. The displacement measurements are all relative, and the dataset has not been calibrated to any ground location so there is a bias of the reference level, which is unknown. This data has not yet been validated. This displacement map should be used as guidance to identify areas of significant ground displacement, and may be less reliable over heavily vegetated areas and steeper slopes. 

The processed interferogram has been uploaded in the ARIA standard displacement product format (see https://aria.jpl.nasa.gov/node/97) as a NetCDF file (S1-GUNW_COSEISMIC-A-R-131-tops-20201030_20201024-160721-38516N_36802N-RR-d813-v2_0_3.nc). This file has several layers including the unwrapped phase of the interferogram. The layers can be extracted with the ariaExtract.py script from ARIA-tools (https://github.com/aria-tools/ARIA-tools) Note that unlike the regular ARIA standard products, this interferogram used the ESA restituted orbits, not the final precise orbits but the rest of the processing is the same. 

The interferogram unwrapped phase was converted to a displacement map with values in centimeters and stored as a GeoTIFF file (S1_A131_20201030_20201024_disp_cm.tif)

(Note: the initial file upload said this interferogram was from a descending track. This has been corrected. The data is the same, but the file name was incorrect.)

Released 31 October 2020; description 31 October 2020

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The InSAR ground displacement results posted here are preliminary results, primarily intended to aid the field response and people who wanted to have a rough first look at the earthquake. This ARIA-share website has always focused on posting preliminary results as fast as possible for urgent response. These preliminary products may or may not be suitable for detailed scientific analysis.

The Sentinel-1 data products contain modified Copernicus Sentinel data, processed by the European Space Agency and analyzed at the NASA Jet Propulsion Laboratory.

The products (ARIA standard product format .nc, NetCDF .grd and GeoTIFF files) are available to download at https://aria-share.jpl.nasa.gov/20201030-Samos-Izmir-EQ/Displacements

For more information about ARIA, visit: http://aria.jpl.nasa.gov

Eric Fielding
ARIA JPL
Last update 31 October 2020