The shutting of train lines in Auckland after this morning's 7.1 magnitude earthquake were just a precautionary measure, KiwiRail says.

The 4.37am earthquake was centred off the North Island's East Coast - about 100km northeast of the East Cape settlement of Te Araroa - at a depth of 55km.

The jolt lasted for almost a minute and was felt across much of the North Island.

However, despite the quake happening several hundred kilometres away, Auckland commuters arrived to Britomart and Newmarket train stations to find the line closed.

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A KiwiRail spokeswoman told the Herald the services were temporarily suspended between Newmarket and Britomart following the earthquake while precautionary inspections were done.

"Services resumed just after 7am once the inspection was finished."

Ongoing delays and cancellations can be expected.

The quake was followed by several moderate-sized aftershocks, including a M5.6 jolt at 5.01am, and a M4.6 quake at 5.03am.