Nisyros: risk assessment, risk perception and thinking beyond the ‘Wow!’ factor

Back to proper walking on Monday.  I have been delaying going down on the floor of the main crater since I arrived on  Nisyros because it is one of great things to do. From my perspective it’s a mistake to do all the best stuff first, better to savour the prospect of some things for later.  I don’t think that a visit to the floor of the Stephanos volcanic crater on Nisyros is in the book “1000 things to do before you die”  ….. but it should be.

You can go there on any one of a fleet of air-conditioned coaches from the harbour but where’s the achievement in that?  It took me less than 2 hours to walk there from the hotel in Mandraki, by now a reasonably familiar but always interesting route and still with a few surprises if you keep your eyes open.  But this isn’t about the walk, it’s about the Stephanos Crater, the biggest, most dramatic and most visited crater in the 4 kilometre-long Nisyros caldera.

It’s very dramatic when seen from around the caldera rim as I hope those who have seen photos of it in earlier blogs will agree.  It’s very dramatic when viewed from the rim of the crater itself.  But it’s only by going down the steep, zig-zagging, blindingly white sulphur path to the crater floor that the true awesomeness of Stephanos grabs you.  For a start it becomes significantly hotter as you go down, not only from the reduction in the breeze, but also from the reflection of the sun from a cloudless sky ….. and from the heat coming up through the floor of the crater.  Believe me, you can feel it through the soles of yours sandals/shoes/boots.

On first impression it looks pretty benign because the bottom of the path emerges in a fairly inactive area.  However, the smell of sulphur has become considerably stronger than it is on the crater rim and following the edge of the floor around to the left it soon becomes apparent why.  There are dozens, maybe hundreds, of small fumaroles constantly hissing and now and again pouring out steam and sulphur gas.  They are surrounded by sulphur crystals, too fine and fragile to take as souvenirs, though crudely smashed bits of fumarole edge attest to the fact that some have tried.

Go around to the far side of the crater and there are countless more sulphur-emitting holes but here there are also holes with boiling mud or water as well.  The configuration changes every year because in winter the floor gets a covering of water which leaves a thin crust of sediment as it dries and then the heat from underneath breaks out at weak points.

And that’s where issue of risk assessment versus risk perception comes in.  Just how safe it wandering around on the thin-crust floor of an active volcano?  How safe is it being anywhere near it?  Talk to some people and they will get no closer than peering over the rim close to the taverna and the safety of the coach.

The given-reasons for not going down to the crater itself are that it’s not safe and the smell is objectionable.  Yet many then go and sit in the taverna and have a cigarette.  That’s perceived risk from the crater versus the perceived risk from smoking.  I’ve never bet on a horse, or anything else, but it seems to me that it’s the difference between a 1000:1 outsider and a sure fire certainty.  Despite the worst endeavours of the tobacco industry it’s now established beyond reasonable doubt that the risks to health from smoking are considerable.  And the smell!!  You stick the things in your mouth and set fire to them in order to inhale the smoke.  Give me the crater floor anyday!

Volcanoes all over the world have for millennia attracted dense settlement of people close to them because of the good-living they offer.  Nisyros has been no exception.  As I have mentioned before the island was once agriculturally very prosperous because of the rich volcanic soils with steep terraces within the caldera and within spitting distance of the main crater.   The people who lived there would have known the risk. The latest major eruption was in 1888 but yet on Saturday I saw houses with dates of 1903 and 1920 carved into the door lintels.  They were still building 15 years later.

It wasn’t that the people couldn’t move.  When the climate changed and the rains failed they left in droves as the wealth of agriculture shrivelled.  Rather, while the living was good they chose to stay.

Risk assessment is scientific, risk perception is largely emotional.  The differences are far too complex to go into in a  short blog.  One factor is that people regard risk with a high statistical probability of happening as acceptable if they feel that they have choice over it, mistakenly seeing ‘choice’ as ‘control’.  There are countless examples.  There is always a huge outcry over the fear of MRSA affecting hospital patients yet many of them are at far greater risk from a lifetime of smoking, or getting to the hospital by car.

When people are on holiday they just want to enjoy themselves and if that means the ‘Wow!’ of walking on the floor of an active volcano in flip-flops then that’s fine.  “It’s my choice.  I’ll do what I want”.

What are the risks?

It is likely that at some point the volcano will erupt again.  One research study concluded that “When looked at in comparison to US volcanoes both scores (detailed in the paper – URL below) place Nisyros in the “Very High Threat (VHT)” category, grouping it with volcanoes such as Redoubt, Mount Ranier and Crater Lake”.  BUT the man-on-the-crater-floor reasons “True! But the likelihood of it happening while I’m here are pretty small”.  Statistically that makes some sense.  However, to be brutally honest, I guess most people don’t think about it at all, assuming blindly “a coach brought me here so it must be safe”.  A little more of which later.

Why there is logic in going to the crater floor of an active volcano is rooted in part in the monitoring of seismic activity.  The people who lived and farmed inside the caldera would have been switched-on to the prescience of wildlife and livestock to there being ‘something brewing’.  I have no doubt that wildlife and even domestic animals are more sensitive to changes than we are, whether it be minute changes in the atmosphere, ground vibration, or whatever.  When our culture stopped being rooted in the land and the environment we lost touch with all kinds of sensitive indicators of pending danger.  But at least we have universities which use all sorts of sophisticated monitoring equipment to give us warning. If there are no warning signs, we feel free to go ahead.  Or rather, if we are not TOLD that there are warning signs we feel free to go ahead.  Don’t forget the film ‘Jaws’ when profit outweighed science and prescience.

But that’s to do with the volcano ‘blowing its top’.  What is NOT taken into account is the very personal and much higher risk of breaking through the thin crust of the crater floor.  It happened a few years ago on Nisyros.  A woman taking photos got too close to a fumarole and the crust broke plunging her leg into boiling water.  She had boots on which limited the damage.  On Monday I saw a young girl in shorts and flip flops within a couple of inches of a hole of bubbling water taking a photo with her mobile phone.

I don’t think anyone would describe me as risk averse.   Our paragliding instructor called the  group of us from the mountaineering club on the training course a bunch of gung-ho idiots (‘idiots’ wasn’t the word but I can’t publish what he did say).  We had T-shirts made with “The Gung-Ho Paragliding Team” emblazoned across the front.

Back to the present, on Monday I was very suspicious of the stability of the crater crust and stayed well away from clusters of fumaroles on the floor itself.  On several occasions I got a blast of very hot air onto my toes from tiny fissures I hadn’t even seen.  Once I nearly stepped in a shallow pool of clear boiling water.  Much of the crust just felt weak and unstable underfoot.

The hordes of day-trippers from Kos who descended onto the crater floor by the coach-load were obviously very impressed by what they saw and posed for photos squatting down next to bubbling or smoking fumaroles clearly oblivious to any risk.  Some put their hands over the openings only to withdraw them again very quickly amid multilingual expletives.

Now here’s a thought, picking up on something mentioned earlier.  Is it that we are so used to risk assessment being carried out for us and checked by government agencies that if we are not explicitly prevented from going somewhere or doing something ‘for safety reasons’ we assume that it’s OK.  Little Jimmy Somewhere fell off a swing and hurt his head. The courts found the local authority responsible, damages were paid, playgrounds across the UK were closed overnight, many never reopened.  Surely better to teach Little Jimmy not to fall off the swing.  We have lost the instinct, the inclination and the ability to assess risk for ourselves.  After all, we can always sue!

Peace and quiet, blue sea, blue sky as I left Mandraki

Terraced fields and roof-top threshing floor in sight of the main crater

Red and yellow sulphur deposits on the path down to the crater

On the floor of the crater

Close-up of part of the crater wall

Monitoring station

slightly raised fumaroles

Sulphur crystals around hissing fumarole

Scale: trippers view the crater from its rim, fumarole below

Fuming fumarole

Fumarole encrusted with sulphur

Sound like a kettle boiling vigorously

… and one with the lid off

More fumes and crater wall

Visitors to the crater floor



Analysis of volcanic threat from Nisyros Island, Greece, with implications for aviation and population exposure.  H. S. Kinvig, A. Winson and J. Gottsmann

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