In the gospel of Mark 13:24, the Greek θλιψις is used. This word is also used in other apocalyptic passages in the New Testament: in Matthew 24:29 and in Revelation (especially 1:9 and 7:14). Θλιψις is generally translated as ‘oppression, affliction, tribulation’ (BADG p. 457), but I think that in these apocalyptic fragments it is a code word for the destruction of the Temple in the summer of 70 CE. So I would argue that the writer is referring to an event rather than a period, and therefore ‘catastrophe’ would be a proper translation in these instances. Revelation 7:14 says οὗτοί είσιν οἱ ἐρχόμενοι ἐκ τῆς θλίψεως τῆς μεγάλης, ‘these are they who have come out of the Great Catastrophe’. The combination of μέγας and θλιψις points to the suggested translation as this was the greatest catastrophe imaginable. In Revelation 1, θλιψις (in verse 9) is associated with ‘the day of the Lord’ (in verse 10), the catastrophic turn of the era in August 70 CE.
In my opinion the apocalyptic texts of the New Testament – the Synoptic Apocalypse in Mark, Luke and Matthew, and the book of Revelation – together with the last, apocalyptic chapter of the early Christian Didache, contain encrypted information on the birth of Christianity that is essential.