The council dealt with bore blowouts about twice a year and this one may have happened due to a sudden drop in the barometric pressure (external air pressure), he said.
The unused bore was a low-pressure bore and in the cold weather the blowout appeared more spectacular than it actually was, creating a lot of steam over the top of nearby buildings and attracting onlookers.
"Dealing with bore blowouts is part and parcel of living in Rotorua, part of what makes this city unique," Mr Brownbridge said.
"There's no reason to believe it had anything to do with anything changing in the geothermal field.
"Rotorua is a lot safer now than just prior to the bore closures of the early 1980s."
Once the bore had been stabilised, grouting - a fine cement - would be forced into the bore under pressure to shut it down and plug any cavities in the ground, Mr Brownbridge said.
The service lane remained off-limits but businesses in the area were operating as normal yesterday.