The last good shake

The only earthquake to cause significant damage in Dunedin occurred on April 9, 1974.

The first of four distinct jolts, at 7.50pm, was slight but it was followed seconds later by one that hit 4.9 on the Richter Scale and then other tremors that lasted for almost 90 minutes.

The Otago Daily Times reported it as a minor quake that caused cracks in "a number" of buildings, broke windows, especially in the South Dunedin, St Clair and St Kilda areas, damaged chimneys, spilt bookshelves and broke crockery and ornaments.

The Salvation Army's Eventide Home in Beach St, St Clair, received "substantial structural damage".

The power went out in Corstorphine for 45 minutes and automatic fire and burglar alarms were set off.

The telephone system was overloaded and the supervisor of the Dunedin toll room said many people dialled 111 but "didn't know what they were wanting".

The lack of information available to the public, who should provide it and how, became central issues in the following days.

About 3000 claims were made to the Earthquake and War Damages Commission.

They were mostly minor and more than half were for damaged chimneys.

The quake was estimated to be 12km deep and centred 10km south of the city.

An Otago Regional Council study has since suggested most of the damage occurred in the area of "deep alluvium" in South Dunedin where there was a higher density of housing and older houses.

And recent work has established the quake may have been on the little known Green Island Fault running parallel to the better known Akatore Fault and about 3.5km offshore.