The false color image below shows synthetic aperture radar imaging from ESA's Sentinel-1 satellite. The map from the 20-Jan-2017 BBC article Larsen ice crack continues to open up illustrates the same general area.
The Larson C Ice Shelf is the large blue-ish region in the middle of the false-color radar image, and is labeled as such. The crack is the thin lighter line just above the red arrow.
Moving diagonally upwards to the right, the gray region is labeled "Sea Ice". Is this just much thinner but mostly solid ice, or water with pieces of ice in it? While the ice shelf seems relatively uniform in tone, the gray sea ice area has a mottled pattern.
Also the boundary between the two regions has what looks to me like some kind of 3D effect - the black, ribbon-like variable width region separating the two. Is this an effect of shadowing from oblique incidence? Is this actually the sidewall height of the ice shelf?
There is also some discussion of radar imaging of sea ice in this answer.
above: Sentinel-1 synthetic aperture radar image of the Larson C ice shelf, beginning of January 2017, found here. Open in separate viewer or tab for full size. The width of the image is roughly 300km, south is towards the lower right. Image credit: ESA/EU/Copernicus
above: Map of the region around the Larson C ice shelf, beginning of January 2017, from BBC here. Image credit: MIDAS Project, A. Luckman, Swansea University. Because it's difficult to read, I'll point out that Wales not shown in it's correct location - it's there for scale only.