According to Geonet, a severe 7.5 magnitude earthquake at a shallow depth of 15km has hit near Hamner Springs in North Canterbury just after midnight on Monday morning.
Although foreign agencies, including the reputable USGS, have just upgraded the quake from an initial reading of 7.4 to a 7.8 magnitude as of 1:45am NZ time.
A Tsunami warning has been issued for the eastern coastlines of the North and South Islands. Civil Defence is advising all residents in low-lying coastal areas to move inland until further notice. The first surges are reported to be hitting the northern coastline of Kaikoura imminently and may reach 2 metres in height.
The earthquake has been widely felt across both islands and phone lines are down near the epicentre making it difficult to assess the damage at this early stage.
Reports of damage from Wellington and Christchurch have started to come in with windows being smashed and masonry crumbling off buildings in both areas. Many people have evacuated onto the streets in the CBD and the sounds of emergency sirens can be heard throughout both cities.
People also self-evacuated from apartment buildings in downtown Auckland, where what began as a light shaking, grew into a more intense rolling motion that saw the streets filled with concerned residents, myself included.
Aftershocks continue to be reported ranging from light to severe, the best place to monitor the ongoing quakes is at geonet.org.nz.