A star-studded line-up of Kiwi musicians will perform tomorrow in earthquake-hit Christchurch in what is thought to be the largest free outdoor concert staged in New Zealand.

The Band Together Concert in Hagley Park is expected to attract more than 100,000 people to see about 35 artists perform, including The Exponents, Opshop, The Feelers, Midnight Youth, Evermore, Bic Runga, Dave Dobbyn, Anika Moa, Che Fu, Ray Columbus and Dinah Lee.

Television and radio presenters will host the event, which will run from noon until 8pm and will be broadcast live. Fine weather is forecast.

The concert is being underwritten by organisers Paul Ellis and Jason Kerrison with the assistance of sponsors, so there is no cost to the city still reeling from the 7.1-magnitude quake that struck on September 4.

Kerrison, the frontman for Opshop, said there had been a rare show of unity between musicians, local authorities and the business world in getting the concert together in little over a month.

"And one myth I would like to dispel is that it's not a bunch of Aucklanders coming down to Canterbury to help Cantabrians. In fact, if you look at the line-up, probably a good three-quarters of us are from [Canterbury], we have grown up here, or we have got our first memories or played our first gigs here."

Ellis, a promoter and former New Zealand Idol judge, said music was a "hopeful tool" for people still struggling with the quake and ongoing aftershocks.

"I don't think that people outside of Canterbury really realise ... how tough it is. And while the rest of the country moves on, we want to celebrate Canterbury with everyone in the park."