Tauranga MP Simon Bridges will never forget the shaking of aftershocks or seeing firsthand the immense damage caused by the South Island's earthquake this week.

Mr Bridges, who is also Minister of Transport and Energy and Resources, has returned home after spending his week in Wellington and north Canterbury assessing the landslides, torn roads and fractured towns that fell victim to the 7.8 magnitude earthquake on Monday.

Mr Bridges joined Prime Minister John Key in visiting the epicentre of the quake. The magnitude was revised on Wednesday and increased from the original 7.5 magnitude to 7.8.

Since the first shake, which killed at least one person and destroyed countless homes, the area has been hit by more than 1000 aftershocks.

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The coastal tourist town of Kaikoura was completely shut off, with many people being flown out by helicopter.

''I've experienced more earthquakes [in the past couple of days] than I ever have in the past,'' Mr Bridges said.

''They start rolling and it's a bit like your on a boat. You feel a real sense of sea-sickness.''

Mr Bridges said the devastation to State Highway 1 was remarkable and it would take a long time to fully come back from. Railway tracks that ran alongside the highway were thrown from their line and parts of the roads were completely wiped out.

''Bluntly speaking, it will need to stay on the coastline. It's incredibly beautiful and it's a good direct route from Picton to Canterbury but there will have to be some changes. The road where it is just isn't going to be safe and it needs to be resilient to future shakes and floods.''

Mr Bridges said trying to work out the future of the highway, with KiwiRail and NZ Transport Agency, had made his week the busiest of his year - and there was still much to do, but seeing the devastation firsthand was something he'd never forget.

''In anyone's work life there's always going to be a few things that you will go back to and remember more than others. For me, the number one was when PSA hit. I'll always remember that and the crisis meetings we had with Zespri and the Government to solve it.

''Then Rena, seeing the oil and the beach and then I will never forget some of the very angry public meetings we had.

''This will be right up there, albeit it's not as local for me as in it's not my community worst affected, but to see the way the mountains have literally moved and the coast - we are literally going to have to put that geography back together again. I'll never forget it.''