Tremors were felt in Perth and Esperance, but no reports of damage so far.
Norseman Hotel worker Angie Hogan fled outside the 1930s pub when the “bar moved”.
“The earth moved,” she said.
“The whole bar just moved. I had to run outside.
“There is no damage, but I’m still shaking. That’s biggest earthquake we’ve had.”
The earthquake’s epicentre was 16km below the surface.
Geoscience Australia senior seismologist Jonathan Bathgate said it was the biggest onshore earthquake recorded in WA since a magnitude 5.7 quake near Derby in 1988.
Friday’s earthquake was comparable to the magnitude 5.6 quake which devastated Newcastle in 1989, killing 13 people.
Mr Bathgate said it was the 15th earthquake in the Norseman area since late May.
“We’ve had people feeling this from Norseman to the coast on Esperance and as far away as Perth,” he said.
A magnitude 5.2 quake struck Norseman in May, which was the biggest since a magnitude 5.0 quake in Kalgoorlie in 2010.
Tremors could be felt at PerthNow’s office on Stirling Street, while Perth residents took to Twitter and Facebook to report shaking.
Anthony Spiteri wrote: “Seems like the CDB building amplified the Perth #earthquake … Most people here felt it. We shook for about 5-10 seconds. Rolling wave!”
Adam Hemmings said: “Did you feel the earth move? Some Perth buildings (including the mix94.5 studios) have been shaken after a 5.6 mag earthquake near Norseman.”
And Beau Mitchell added: “Did #Perth just have an #earthquake? My apartment was shaking!”