The information graphics created to inform people on the Samoan tsunami about to hit New Zealand didn’t send a clear message.
When disaster hits it spreads on the internet like wildfire. But the information graphics the public are served up are next to useless for making an informed decision on whether or not you’re in imminent danger.
Yesterday morning I arrived at work, opened Twitter and found out about the shocking Samoan earthquake – my contacts on the social networking site said the tsunami was heading toward New Zealand and would be here within hours.
So we’ve heard this before – a tsunami is on the way – don’t panic (yet). Do some quick research – so how big is it? 10cm or 10metres? Where will it hit? Should I phone home and warn the family?
The main New Zealand news websites gave conflicting information and seemed at least an hour behind the news on Twitter. Who could I trust? I found a lot of misleading information and hype from both the public and officials.
So I turned to the New Zealand, Australian and US government websites for the facts – they’d be accurate and up to date right?
A number of local Twitter posts pointed to the following tsunami gauges published online by GeoNet – a New Zealand Government owned geological hazard monitoring system in New Zealand:
So in the heat of the moment how would you interpret this diagram?
- A really massive wave will, or has, hit North Cape?
- A tsunami of approximately one metre will, or has, hit Wellington?
- A tsunami of approximately 10 metres will, or has, hit Auckland?
Yesterday the above graph looked nonsensical to me.
I’m sure it makes sense to experts but it’s plainly a bad information graphic for the general pubic who just want to know – where will it hit and how large will it be?
It also turns out that this graph is retrospective – it measures actual sea levels – so is not a prediction. But, yesterday, in the heat of the moment I didn’t realise that.
So I ended up relying on Twitter reports that a wave of around one metre would be hitting New Zealand’s East Coast with some minor effects in Wellington harbour and the West Coast of the North Island.
After going back to the graph today and reading the small print it appears that the wavy lines represent the normal variations of the daily tide. The grey jagged lines represent abnormal variation, and I’m guessing, intensity of force – the effect of the earthquake and resulting tsunami. You determine the height not by the height of the graph, but by the ‘One Metre’ ruler – imagine this ruler slides up and down the graph.
So based on this interpretation, Raoul Island and East Cape were hit by an intense tsunami of around one metre. North Cape and Chatham Islands hit by tsunami of less than half a metre. The other New Zealand locations hit by a minor tsunami just a few cm high, barely noticeable.
But GeoNet is not alone – even worse – this ‘Water Column Height’ graph from the US Government’s NOAA (National Data Boy Centre) could give the distinct impression the wave is over 4963 metres. Help!
Other information graphics from NOAA were more useful than most but on the whole too little, too late and not enough detail.
I believe we need a better way to quickly inform the public, not just where the tsunami originated, but where it will hit, when, with what intensity and height and who is in danger.
Information graphics could play a key role in informing people who might be in a panic and not thinking straight.