He said it only had to be replaced once a year and was important for basic biological needs, to help cook and prepare hot drinks, and for hygiene purposes.
People also needed to be alert of their food needs in an emergency, because supply chains could be interrupted, he said.
Mr Michael said another important thing was the ability to reunite with family.
Though yesterday's shake happened at night when most families would have been together, that was not guaranteed and emergencies could happen during a time when people were out and about, he said.
Therefore, families needed a plan of where they were going to meet and how they were going to reconnect if an event took place, Mr Michael said.
"Another thing today that's more important than ever is to know your neighbours."
He said neighbourhoods were the smallest form of community which could provide people with support.
He said for every institution and organisation it was part of business as usual to do drills.
Although families did not have to do formal drills, emergency plans "should not be out of sight and out of mind", Mr Michael said.
"The only thing we can do is have a plan."
He said Rotorua Lakes Council had a legal obligation to co-ordinate a response to an emergency, and it had an emergency operations centre where between 90 to 100 staff were trained for emergencies.
According to a survey this month,just over half of Rotorua's residents would be fully prepared in the event of an emergency.
The results of the Community Satisfaction Survey, commissioned by the Rotorua Lakes Council, showed 51 per cent of residents had a household emergency kit. The rest did not.
It surveyed 400 residents this year and the finding was similar to last year's result.
GNS Science duty volcanologist Michael Rosenberg said that on top of geothermal areas the ground was softer and behaved in a "more jelly-like" way in an earthquake.
Softer ground, including geothermal ground, could amplify the seismic waves, he said.
Emergency information resources:
-www.civildefence.govt.nz
-www.getthru.govt.nz