The September 2010 Canterbury earthquake, its deadly February sequel and the thousands of aftershocks (including more than 20 greater than Richter magnitude 5) have generated so much news coverage that a documentary about the subject risks being superfluous.
But Smyth adds much to the record with a effectively discursive view of the quakes and their aftermath that emphasises the human dimension rather than taking the incident-driven approach that news crews adopt.
Smyth, who made Barefoot Cinema, the excellent documentary portrait of the shoeless prince of New Zealand cinematographers, Alun Bollinger, is from Christchurch and hoisted his camera on to his shoulder soon after the first shake.
As a result much of the film's first half is drenched in a sobering irony as people celebrate a lucky escape: "Someone's looking after us; we have been big-time blessed," says one woman. Another glumly accepts that "there could be another in five minutes' time" (cue February).
Usefully, the film sets the disasters in context, both geological and historical, but it's at its most affecting when devoting time to personal stories - of an elderly woman who is afraid of the nights; a baker living in a bivouac; a young woman who picked rocks off her dead father's body in the hills above Lyttelton.
For that reason, visits to rebuilds of San Francisco and New Orleans with urban designer James Lunday seem jarring, not just because they are so fleeting. They make room for some high-sounding platitudes that are so conspicuously absent from the film as a whole.
At its best, it's a moving testament to the people of the munted city, and it will form a valuable part of the historical record.
Director: Gerard Smyth
Running time: 105 mins
Rating: M (offensive language)
Verdict: Goes places news crews can't reach