Christchurch Mayor Bob Parker says the first tsunami sirens will be in place along the city's coast within two months.
The 47 sirens will be installed from Waimairi Beach in the north to Sumner in the south.
Mr Parker says work is under way to install the sirens.
He says tests on the sirens will be carried out soon, and then more details will be announced about the system.
Mr Parker says the council will then look at extending the sirens to other coastal and inland areas around the rivers.