Warp core breach

Using a force field during a Warp Core Breach

If the problem is limited to a pressure breach of the warp core and the matter antimatter (MAM) reaction has been stopped, then internal safety shields should contain the explosion and there will be a major mess to clean up afterwards.

If there is a developing fault, and the engineers cannot stop the MAM reaction by (say) stopping the matter flow, then there should be time for a warp core ejection to be attempted.

If the breach occurs suddenly without warning whilst at power – i.e. the MAM reaction is still in progress - then it is unlikely there will be any time to even eject the core, or say your prayers.