The flight paths are planned specifically so any potential debris has a high chance of landing in the ocean.
If it actually exploded (either on its own or because the flight-termination system kicked in) most of it should burn up on reentry though.
The launch license requires them to build in a "flight termination system" which makes it explode if they lose control over it.
There's an autonomous flight termination system which triggers if it strays outside the planned flight corridor; any debris that survives reentry should then land in the advertised safety zone.
If it doesn't explode it might be light enough to survive reentry, after sailing on for a short while. In that case a large chunk of metal will come down either off the coast of South Africa or if continues on in its orbit potentially off the coast of Australia.
[1] has the planned flight path, as well as the impact zones.
1: https://flightclub.io/result/3d?llId=c5566f6e-606e-4250-b8f4...
the onboard control system and flight termination system are programmed to explode if it deviates from a specific and allowed path of trajectory/speed/functional engine thrust. The last thing anyone wants is a partially broken starship going into an uncontrolled suborbital velocity that lands on a city in Africa.
They have a bunch of explosives strapped on the rocket and can give a radio command to blow the ship up. It can even decide to explode itself if the readings go haywire.
It is called the Flight Termination System and it is very common on non-manned flights now.
If that system fails, can the rocket be shot down in time?
What happens if it doesn't explode and they just lost control over it? I'm mostly curios of the risks at that altitude.