Theory: Nova Prospekt didn’t explode, it imploded. As we see in Black Mesa East, the teleporter is powered by a Xen crystal. The Xen Crystals also power the gravity gun, which uses (presumably) anti-mass to defy gravity. Time and space are relative to gravity, so whenever the teleporter is used, time and space are being moved at the speed of light to Xen and back, while using Anti-Mass to bring the subject (i.e. the cat, Gordon, Alyx) to the second destination instantly. When the teleporter in Nova Prospekt is damaged and semi-fails, the Anti-Mass of the Crystal somehow switches (possibly a Resonance Reversal from Decay?) creating extreme time dilation, slowing down the process of time and space folding, and creating such a heavy mass the facility implodes. Keep in mind, I’m not an expert on ANY of these subjects. This is all pure speculation using my extremely limited understanding of time and space.  “Come take a look at this, Gordon,” Eli Vance showing off the Anti-Mass Spectrometer connected to the teleporter.  Final Hours of Half-Life: Alyx
This is the kind of speculation I LOVE. Where did the speculation on Xen crystals having anti-mass come from, if I may ask? ALSO, how do you think Black Mesa managed to get to Xen initially without the use of Xen crystals? It was revealed that they use Xen crystals to tune (or power or operate in some way?) their telporters as seen during Blue Shift and Half-Life 2, so I personally imagine there's more than one way to teleport in the Half-Life universe (as made obvious by Aperture's whole shebang) and Black Mesa was basically poking around in the dark with their initial experiments. The Xen crystals basically act as a portal tuner of some kind.
Black Mesa just sorta fucking around in the initial experiments would explain why you find dead HEV scientists in seemingly completely random places. In Freeman's Mind, he theorizes that the teleporter just kinda dropped people wherever, which would make sense.
I assumed they had anti-mass because they put them into anti-mass spectrometers which I’m assuming measures the anti-mass
Also, regarding the lack of crystals initially used for teleportation: 1) Aperture doesn’t use crystals so maybe Black Mesa messed around with their “stolen” tech 2) I have a theory that either the Nihilanth allowed people into Xen as a way he could escape to Earth in the long term, or maybe the G-Man had some mysterious intentions and provided the first Xen crystal necessary.
Also Also, in Gordon Freeman’s letters (check the Overwiki for those) he mentions ever object having a set resonance so the resonance of the crystal is high (or something like that, I’d have to check back on that) so maybe anti-mass and resonance is interchangeable words? I’d have to do more research for this however.
The idea of Nova Prospekt imploding is so much more terrifying than it exploding, and I'm all for it.