Residents of Christchurch's worst-affected suburbs have been suffering acute depression since the earthquakes, according to a new study.
The University of Canterbury research says since the quake on 22 February last year, clinically significant levels of depression, acute stress and anxiety symptoms are prevalent in the worst-affected areas.
Researcher Amy Rowlands compared the depression symptoms of 200 people in two demographically-matched communities that were affected differently by quakes.
Ms Rowlands says that people's exposure to ongoing aftershocks may have important implications for the assessment of traumatic stress-related disorders and the provision of services following natural disasters.
Prolonged periods of helplessness and ongoing post-disaster disruptions, along with distress and anxiety, were found to be factors associated with the instances of depression.
The 6.3-magnitude quake in February struck west of Lyttelton, killing 185 people and causing major damage in Christchurch and surrounding areas.