A total event collapse was a time explosion which caused the universe to collapse totally, both spatially and temporally, hence the name.

A total event collapse could be caused by a TARDIS exploding, as happened when the Doctor's TARDIS exploded. The Eleventh Doctor seemed to know of total event collapses and that the only way to stop one was to reboot the universe. Some things could survive a total event collapse if they were at the centre of the explosion before they were also erased from existence, as took place with the Earth. (TV: The Big Bang)

The Doctor noted that every sun would "supernova at every moment in history" and that "the whole universe [would] never have existed". (TV: The Pandorica Opens) Though Earth's sun went supernova, Earth itself, at the "eye of the storm", survived longer as a meta-temporal event. Ironically the TARDIS, the cause of the explosion and the sun's erasure, took the place of the sun, burning up over millions of years and thus keeping the Earth warm enough to develop life and civilisation. From the Doctor's viewpoint, the Earth, the moon and the exploding TARDIS existed until 1996, when they too began to fade. Aside from the Moon, the exploding TARDIS, and Earth and its inhabitants, every star, planet, life form and object was erased from the Universe, past, present and future. Those races present near the initial explosion, namely, the Pandorica Alliance, were preserved as stone statues. These species included the Daleks, Cybermen, Judoon, Hoix, Silurians, Roboforms, Sycorax, Sontarans, Zygons, Drahvins, Terileptils, Atraxi, Haemogoth, Raxacoricofallapatorians, Blowfish, Uvodni, Chelonians, Draconians, Autons, Weevils and the Nestene Consciousness.

The Doctor negated the total event collapse with the Pandorica, which contained a few billion atoms of the former universe. He flew the Pandorica into the heart of the exploding TARDIS, sending the Pandorica restoration field across every point in time, thus creating a second Big Bang that successfully rebooted the universe. (TV: The Big Bang)

A total event collapse could also change some species' histories. A Cyber-Leader noted that "all universes will be deleted", which indicated that total event collapse would also affect parallel universes, by erasing them along with the universe in which the explosion occurred. (TV: The Pandorica Opens)

Behind the scenes[]

The non-fiction TARDIS Type 40 Instruction Manual expanded on the Total Event Collapse Incident by specifying how the Doctor's TARDIS was sabotaged, causing it to explode whilst travelling in the Time Vortex:

All time travel is theoretically dangerous, but operators should be aware that in extreme circumstances the destruction of a TARDIS whilst in time travel mode could result in a Total Event Collapse, effectively causing the destruction of all matter both spatially and temporally.