Like a few other comments here, I too saw this as a ten year old when it first aired as a TV movie of the week. I think it was right after the Poseidon Adventure came out and I was on my disaster movie kick. But I really loved this one. I remember being riveted to the TV, the hot, steamy subway at night and the dark, moody sets and effects. From what I remember there was an earthquake in Manhattan, and the implication was there wasn't much for them to escape to once they got out.
That's why I hated the longer version that was released a few years later. They explained it all away as a terrorist explosion or something. It was all padding, probably to fill a 2 hour slot (just like that awful Debra Lee Scott padding they added to Earthquake for its TV airing.)
I would also love to see this again. Or maybe not... maybe it would ruin the memories.
FYI: another fun TV movie from this era was Terror At 30,000 Feet, with William Shatner as 747 pilot and his demonic cargo.