Researchers concerned at Hutt Valley suburbs' post-quake confusion

Just a third of people in tsunami-threatened Petone and Eastbourne evacuated to higher ground within the recommended 10 minutes after the Kaikoura quake. Photo / File

A new Wellington study has highlighted the confusion that followed the Kaikōura Earthquake, with only a third of people in tsunami-threatened Petone and Eastbourne evacuating to higher ground within the recommended 10 minutes.

The official response to the November 14, 2016, event has drawn much criticism - and a Ministry of Civil Defence and Emergency Management report out last year acknowledged shortcomings in how it had issued tsunami warnings, and got the right staff in quickly.

In a new study released today, researchers surveyed residents in Eastbourne and Petone, Lower Hutt to find out how they responded to the tsunami threat that came after the midnight 7.8 quake.

It revealed many people were confused about how they should react to the quake, did not evacuate immediately, and often evacuated by car, causing congestion and slowing evacuation efforts.

"Results showed that while 69 per cent of respondents did evacuate, only 33 per cent evacuated within the recommended 10-minute window," said the project's lead researcher, Dr Denise Blake, of Massey University.

Others took anywhere from 10 minutes to over three hours to leave their homes and seek safer ground, either further inland or at higher elevations.

The researchers found the length of people's response time concerning - particularly as a quake from the nearby Hikurangi subduction zone could send a tsunami rolling into the Hutt Valley within minutes.

Nine per cent of respondents said they evacuated twice in a short space of time, indicating that some people were not sure whether evacuation was the right thing to do, or if there was a tsunami risk.

Another area of confusion was around whether residents needed to evacuate or not.

"Only 11 per cent of respondents evacuated their homes because of feeling the quake, despite 70 per cent of people recognising that it was strong or severe."

The Ministry of Civil Defence and Emergency Management have since launched a nationwide tsunami campaign instructing people that if the quake is "Long or strong, get gone".

Tsunami evacuation zone maps for the Wellington region had also been made available on WREMO, Wellington City Council and GNS Science websites.

The study further highlighted that traffic congestion in an evacuation is an issue in the Hutt Valley area.

Tsunami evacuation advice recommends that people evacuate by foot or bicycle to prevent congestion, but respondents preferred to travel by car, with 64 per cent of people using vehicles to evacuate.

This caused traffic to build in the evacuation zone, stopping people from being able to reach safe ground quickly.

The number of people evacuating by car was likely increased by the flat nature of the Petone area, meaning that some people had to travel up to 4km to reach the tsunami safety zone.

But the researchers pointed out that, in the Kaikōura quake's case, it was fortunate that tsunamis that resulted from the event was only damaging to a single bay in Banks Peninsula.

A major tsunami preparedness exercise was being planned for October 18, with people in vulnerable coastal spots being encouraged to work out their best evacuation routes.