The Dominion Post in Wellington reported GNS Science said a 3.6-magnitude temblor at 10 a.m. centered near Waipawa was followed by a second one measured at a magnitude of 5.2 at 10:48 a.m. centered at Hawke's Bay near Waipukurau.
"It's very hard to describe the noise but it was like a dull knocking sound," Juliet Smith of Waipukurau told the Post. "Then there was quite a jolt and then it turned to rocking. That lasted about 20 seconds."
She said the quake didn't damage her house.
Hawke's Bay civil defense spokesman Nigel Simpson said there had been no reports of damage.
Geonet said the quake, which was felt as far away as Wellington, was not directly related to Canterbury's 7.1 Saturday earthquake other than both were caused by the same two geological plates shifting.
The cost for repairs related to the 7.1 earthquake was being estimated at about $2 billion, with at least 100,000 homes damaged, authorities said.
Prime Minister John Key has announced a $5 million donation to the emergency fund set up up to begin rebuilding in the Canterbury region and the city of Christchurch, Fairfax Media reported Monday.
The private sector has already donated $6 million.
New Zealand's minister for economic development, Gerry Brownlee, has been appointed to oversee the rebuilding efforts, Key said.
Preliminary surveys by the Treasury suggested there would be "considerable disruption" to both the Canterbury and national economy in the short term, he said.
About $94 million is immediately available in the emergency works fund for roads "for use across the country" for the rest of the year.
"It's definitely not enough but it's enough to get started," Key said.
Key expressed his sympathies to those affected and said he was struck by the power of the quake. "It was miraculous nobody was killed."