Exploring an anniversary effect three years after the February 2011 Christchurch Earthquake

The anniversary of a traumatic event can lead to psychological distress. Though triggers of psychological distress have been generally documented in the trauma literature, the impact of earthquake anniversaries is less well understood, particularly in relation to when distress symptoms are most heightened. The present study investigated an anniversary effect on psychological distress three years after the February 2011 Christchurch earthquake, whether this effect differed in communities with different levels of physical impact or financial resource, and if it was more pronounced before or after the anniversary. Respondents were from six Christchurch suburbs differing in socioeconomic status and physical damage from the earthquake. Psychological distress was assessed via self-report measures of posttraumatic stress, depression, and anxiety. Assessment took place 2-3 weeks before the third anniversary (n = 300) and 2-3 weeks after it (n = 300). Symptoms of posttraumatic stress and depression were greater after the anniversary than before, particularly in medium to low socioeconomic status suburbs and those suburbs that experienced greater physical damage from the earthquakes. Contrary to predictions, the findings demonstrate a delayed anniversary reaction that manifested in the weeks following the earthquake anniversary.