This data set contains processed multibeam sounder data from 12 dives of AsterX AUV performed on active faults scarps of the North Anatolian Fault system in the Sea of Marmara during the Marmesonet cruise (2009). The AUV carried a SIMRAD EM2000 multibeam echosounder, operating at 200 kHz, and surveyed at 50 to 70 m altitude, allowing a swath width of 150-200 m. Digital Elevation Models (DEM, in meters below sealevel) and seafloor backscatter intensity mosaics (relative amplitude in dB) are provided for 7 zones: Tekirdağ Basin W (dive 13), Tekirdağ Basin NW (dive 14), Western High (dives 10, 11 and 12), Western High E (dive 15), Central High (dive 6,7,8 and 9), Çınarcık Basin N (dive 16), Çınarcık Basin S (dive 2) (see figure). The horizontal resolution and grid pixel size of the DEM is 2 m. That of the backscatter intensity image is 1 m. Two versions of the DEM are provided. Version 1 is consistent with the backscatter image. Version 2 was updated applying a Fofonoff correction to the depths and relocating part of the AUV multibeam sounding points to fit EM302 shipborne multibeam maps. Version 2 depths and absolute positions are more accurate (10 m in the WGS-84 reference frame), but Version 1 will give better results if the backscatter image is applied as a texture or shading on the DEM. DEM and Backscatter raster files are provided in GeoTIFF format (readable with ArcGis 10.3 and QGIS 3) and use projected cartesian coordinates. They were converted from CARAIBES (Ifremer bathymetry and imagery processing software) output raster files with QGIS using GDAL translator. The Coordinate Reference System is a world Mercator projection based on WGS-84 datum, using meter units and a standard parallel at N40° latitude (latitude of preserved scale) {proj4: +proj=merc +lon_0=0 +lat_ts=+40 +x_0=0 +y_0=0 +datum=WGS84 +units=m +no_defs}. For GIS skeptics, one possible way to use these grids with Generic Mapping Tools is to perform a reverse projection back to geographic coordinates. Assuming the default PROJ_ELLIPSOID is properly set to WGS-84, the reverse projection can be applied (using gmt version 5) with the following command line: gmt grdproject AUV_XXX.tif=gd -GAUV_XXX.grd -Jm0/40/1:1 -F -C -I -V