The most recent tremor hit the city at about 1326 BST on Tuesday.
It lasted around three seconds and caused buildings to shake.
Julian Bukits, a seismologist from the British Geological Survey (BGS), told BBC News Online: "We are analysing the data to find out the magnitude, but from what witnesses are saying it was a significant event - perhaps as strong as the first one on Monday."
It follows the four tremors which hit the city on Monday, one of which measured 3.9 on the Richter scale.
They were followed by another series which began at about 0440 BST on Tuesday.
Shook buildings
The BGS confirmed a tremor measuring 2.9 on the Richter scale struck at 0439 BST on Tuesday and the second 15 minutes later measured 2.0.
Out of the latest shocks six were too small to register, the BGS confirmed.
The first earthquake, measuring 3.2 on the Richter scale, shook the area at 0845 BST on Monday.
Four hours later it was followed by an earthquake 11 times more powerful which shook buildings across the city.
There were then powerful aftershocks.
The BGS said the lunchtime earthquake measured 3.9 on the Richter scale.
Hundreds of people called the emergency services and other authorities.
'Distinctive'
The BGS said there was heightened interest in earthquakes following the Dudley tremor last month.
That was a much more powerful 4.8 on the Richter scale.
"That's what makes the experiences in Manchester different. It's not one big bang.
"It makes it interesting, distinctive and unusual."
He said such tremors were quite common in the UK and there was no evidence they were getting worse.
'Hair-raising'
Witnesses in Manchester city centre, said buildings shook during the tremors.
Legal secretary Lyndsey Fellows, 27, who works in the Royal Exchange in St Ann's Square, said she was at her desk when she felt the earthquake.
"The computer screen just started shaking and you could feel the floor moving," she said.
"I thought it was a car crashing outside."
Alan Birchall, senior security officer at the Royal Exchange, said he feared a bomb had gone off.
"I was on the roof carrying out an inspection and heard a bang," he said.
"I felt the roof move and my legs wobbled.
"It was pretty hair-raising. I thought it was a bomb, a plane crashing or an earthquake."
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