Civil Defence Minister Chris Tremain is refusing to answer questions on why it took 100 minutes for Taupo-based emergency management staff to be told of Mt Tongariro's eruption last month.

And an email failure later on the day of the eruption left Civil Defence staff in the dark for hours.

Taupo District Council emergency manager Phil Parker asked the Civil Defence Ministry why he did not get a call until 1.30am on August 7, 100 minutes after the eruption.

The minister was repeatedly asked for an interview late last week on whether the delay was acceptable but was told by Jenna Raeburn, in Mr Tremain's office: "There is simply nothing more that the minister can add."

Mr Parker attended the Central Plateau Volcanic Advisory Group meeting in Turangi on Thursday where the delay and the email failure were raised.

Waikato Civil Defence Emergency Management Group controller Lee Hazelwood said, before the meeting, that he would have expected Mr Parker to be told of an eruption within 15 minutes.

After the meeting, where he heard Civil Defence staff closer to the eruption had heard within 15 minutes, Mr Hazelwood was a little more understanding. "I am not saying it was as fast it could have been [letting Phil know], but it's not as bad as I first thought . . . We need to streamline our processes a little more."

As a result of the 100-minute wait, everyone in the emergency response phone tree will have to supply two phone numbers.

Civil Defence information manager Vince Cholewa said people close to an eruption were always going to be the first to know.

Mr Parker has since met with locals and asked to be the first one they call if there is a next time.

Turangi resident Bubs Smith, spokesman for Ngati Tuwharetoa, attended the meeting. "Certainly communication could be streamlined a bit better, and that was one of the outcomes," he said.

Later that day a situation report on the eruption failed to be sent to about 300 people.

The report should have been sent on behalf of the Waikato Region Civil Defence Emergency Management Group before 10am on August 7 and he discovered it had not when one of the agencies expecting it rang at about noon asking about it.

The council's IT system has been modified to inform staff of unsent emails.

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