It actually looks like the ocean level went up in those after pictures.
The beach sand was washed away.
I completely agree but I think it's more an issue of the land subsiding then the ocean rising. I've been thinking about this the last few days. There's been numerous reports from Indonesia of some islands off the coast literally "disappearing". Maybe they're not talking about the buildings, but the actual islands. The Banda Aceh area is to the east of the subduction zone, on the 'up' side of the fault. If there was 30m of upward thrust at the fault then I think it's reasonable to presume there might have been some downward movement further in. It would be as if the crust was tilted, or tipped upward at the faultline causing a downward tilt further in. In that case the land would subside or even "disappear".
Or the island sank?