Violent aftershocks rattled Christchurch Tuesday as parts of the city re-opened for the first time since New Zealand’s biggest quake in nearly 80 years.

The official geological monitoring service GeoNet reported more than a dozen aftershocks overnight, two measuring magnitude 5.4, prompting authorities to evacuate 70 people sheltering in temporary accomm

odation in a high school.

Christchurch mayor Bob Parker said the aftershocks were further damaging weakened buildings in the South Island city of 340,000 people and playing on residents’ frayed nerves.