This led to slow loading times or complete failure to load the website at a time when everyone in the tsunami red zone was being told to evacuate to higher ground.
The National Emergency Management Agency issued a beach and marine threat for Hawke's Bay after the morning's third large earthquake struck at 8.28am, an 8.1 magnitude quake near the Kermadec Islands.
HB CDEMG group controller Ian Macdonald said the interactive maps were now working.
He said the investigations had shown the webserver was under-resourced to handle such a large amount of traffic, but this had been sorted.
"Measures have also been introduced to preventing this from happening again," Macdonald said.
"The web server capacity has now been vastly improved by adding additional resources to the platform."
Macdonald also apologised to people who were confused by a Facebook message posted shortly after the 2.27am Te Araroa quake advising there was unlikely to be a tsunami threat to Hawke's Bay.
The post was then removed ten minutes later.
"We've tightened our processes, but as I'm sure the public can understand the information we get in these fast-moving situations can and does often change quickly," he said.
The group controller said the nature of tsunami risk assessment was time consuming and uncertain and its vital people take precautionary action.
"If it's long or strong get gone," he said. "People need to make their own decision to self-evacuate – do not wait to read about it on social media – if you live in an evacuation zone and feel a long strong earthquake you need to move quickly."
Macdonald added that if you are in a tsunami evacuation zone you should plan and practice self-evacuation with yourself and your family.
There was minimal earthquake damage from Friday's quakes.
A Hastings' Westpac bank spokesman said the branch's closure on Friday was nothing to do with the earthquakes.
It continues to be shut temporarily whilst it undergoes a separate building assessment.
