I think that is more to do with (a) the thickness of the block - to (air) season timber you reckon on 1 year for every inch of thickness for hardwoods (b) it is basically half a log which is almost guaranteed to have massive internal stresses and (c) the growth ring density varies hugely from the center to the edge of the photo, and that puts enormous internal stresses on the wood. That log has seen some major seasonal changes - the growth ring density varies by a factor of 50 or so - might even be higher.
The way to think of wood as as a stack of straws following the grain of the wood - in life they carry the sap up the tree. In the photo you are looking at the end of the straws, and it is through that cut end that moisture is lost. Since the density of "straws" varies according to the density of growth rings, moisture is lost differentially across the log, building stress.
What I'm saying is that it is almost inevitable that the wood I'm looking at is going to crack in some way, usually following the growth rings.
Often blocks are supplied with a wax capping over the end grain to prevent the wood from cracking during transport, but that is no guarantee. I brought some cocobolo (an eye wateringly expensive rosewood) blocks into the house too quick, and I could hear them ticking as the damned stuff cracked. I've also cut thick veneers (~2mm) out of blocks, and after a short time they warp concave or wavy as a result of internal stresses
There is basically nothing you can do though. Even if you were to run some theoretical glue down the cracks, the wood would simply find the next highest internal stress and crack there. Look upon it as a feature that adds character to the wood.
Forgot to mention that when I'm making something (I'm a trained amateur) I cut and plane all the parts oversize and then bring them into the house for a month or so, so that the humidity is right and the wood gets its final moisture content sorted out. The parts move around a bit, hence machining oversize. Then I plane and thickness to final size and assemble and finish. All this is the same reason you make drawers with enough vertical clearance. Seasonal changes in humidity can cause the height of the drawer to change by a percent or so - and if you make a nice piston fit when the humidity is low it will jam absolutely and immovably solid when the humidity goes up.