In this image two TerraSAR-X StripMap acquisitions (3m resolution) from two different acquisition dates and a change layer are composed into a Colour Composite, thus changes in the area of the Eyjafjallajoekull Volcano, Iceland, are highlighted in different colours.
The first image acquired on March 25th, 2010 is represented by the red channel, the second image acquired on April 16th by the green channel and the difference between both images by the blue channel.
In the Eastern part of the map (East of the caldera of the volcano) light blue structures are visible. These are features caused by the first erruption on March 20th, which took place a few kilometres east of the glacier in the Northern slopes of Fimmvörðuháls mountain pass.
In the center of the map the caldera of the Eyjafjallajoekull is displayed by red, green and yellow colors. The bright red color is caused mainly by the eruptive column, which formed due to the second erruption at the top caldera of the volcano. In the image acquired on April 16th the radar signal in this area shows a very low return, which might result from water vapour within the plume. The orange, dark red, yellow and greenish colors are caused by changes of the backscatter values for the areas covered by snow, which have been effected by the erruption (coverage by ash, melting of snow etc.).
In the North of the crater a round structure in light blue colour is visible. This used to be a lake filled with water on the first acquisition. Following the eruption, which started on April 14th, it was filled with material from the eruption. West of the former lake red structures indicate the newly formed melt water flows of the melted ice, which covered the central crater.