Focus on the essential following White Island eruption


A few days after the White Island eruption, the blame games, the speculation and the conversations that need to wait a bit longer yet, are getting underway. I have seen people commenting on matters such as whether tourists will be allowed back on the island; what this means for activities with an element of risk attached. I am seeing people – the ones commonly known as “armchair critics” – passing judgements that are in many ways, premature, ill informed and most probably detracting from the more immediate conversations.

New Zealand, the media and the public need to focus on the essential aspects:

  • The families of the dead, injured and missing
  • The dead and the injured
  • Retrieval of the missing from the island
  • The fact that White Island is still at an elevated alert, still capable of having another explosion

The families of the dead – what a horrible situation this must be for them. Irrespective of whether they are locals or not, knowing that their loved one/s are dead and that some of them might be still stuck on an unstable, venting volcano really is the stuff of nightmares. For them this will be a conflicting mass of emotions. Fear and anger, an insatiable appetite for answers, grief and pain all potentially happening in a horribly chaotic and random emotional spectacle.

How could this have happened in New Zealand? What were their loved ones doing in such a dangerous location? Why are the authorities not trying to get them out? Which hospital do I contact and how?

The dead will have suffered horrible injuries – a mixture of impact injuries from being struck by ballistics (rocks ranging from fist size up to small cars)and burns from being caught in what appears to have been a surge cloud generated by the explosion, and most likely a couple hundred degrees celsius. Identifying them will be a pain staking process and involve a different set of observations to those taken of the 15 March 2019 terror attack victims in Christchurch or victims of the Christchurch earthquake on 22 February 2011.

The Disaster Victim Identification team, who have the difficult, horrible and painstaking task of trying to identify the victims have assembled in Whakatane. This will be a brand new problem never to have happened in New Zealand before. With no prior experience of D.V.I. on victims of volcanic activity this is all potentially uncharted territory in terms how to go about the work. I wish them luck.

Right now White Island is still at an elevated level of unrest – at Alert Level 3 it is still experiencing minor unrest, and conditions exist which are considered favourable for another explosion.

Whilst this is the case there is no prospect for getting the remaining bodies off the island without putting those involved in undue danger. No doubt this will upset and possibly anger a few people, but safety is absolutely paramount – given the lack of warning in the minutes immediately prior to the eruption that one was imminent, were one to happen whilst the rescue team were on the island, they themselves could easily become casualties.

Later on the time will come for a bunch of conversations, which will need to include:

  • How we communicate natural hazard risk in New Zealand
  • Reform how we teach natural hazards in New Zealand schools – earthquakes aside New Zealanders are poorly informed about tsunami, volcanoes and a range of other hazards
  • How ready we are for a major volcanic eruption
  • At what point do activities become too risky and who takes responsibility for the risk

The time for these conversations is coming. They are important ones to have and when the time comes it needs to be an honest conversation. But that time is not now.

 

A volcanic wake up call for New Zealand


In January 1991 I visited White Island volcano in the Bay of Plenty with my parents. It was an awesome yet surreal place, completely hostile to everything except a colony of birds living on its flanks and broken scrub in which they had made their homes. It helped to fuel a long standing interest in volcanoes and a desire to work on them. But nearly 29 years later in an eruption in broad daylight it has shown New Zealand and the world why volcanoes command respect.

The eruption at 1411 hours New Zealand time 09 December 2019 was tiny by global standards. It only lasted a few minutes, but in that time it has killed one person, injured 23 and left another 27 unaccounted for.

So, how did one small eruption that would probably have been forgotten by many by the end of the year except for the fact that it was lethal, manage to cause such grief? And how can this be prevented from happening again?

White Island is a volcano with a crater lake covering the main vent. Between the water and the magma below there is a layer of sediment that changes in chemical composition to almost crystallize and bound the debris covering the vent together. If the magma is at depth then fumarole activity will be lesser because the sealed vent provides less routes for the vapours to escape. As it rises the fumarole activity increases. Directly above the magma a mass of volcanic vapours rises towards the surface and as it pushes its way through the fluid saturated debris steam pressure builds. When the overhead mixture can no longer sustain the pressure it explodes.

Unfortunately eruptions through lakes tend to happen with quite short notice – only a few minutes in some cases, though the warning signs might be overt: seismic activity, a disturbance in the crater lake and increased venting. In the case of White Island where the boat/helicopter is some several hundred metres from the vent, even if they ran back, they might not make it before the explosion.

The explosion in a confined space can be devastating. A cloud of superheated rocks, mud and steam will expand at several hundred metres per second in all directions. If conditions permit a ground surge of falling debris will move across the crater floor and immediate surrounds at possibly over 100km/h. Whilst there are instances of people surviving such conditions, their injuries are likely to be acute. Based on the available footage of yesterday, that is what appears to have happened.

White Island, like New Zealand’s other volcanoes is monitored 24 hours a day 7 days a week by GeoNet, which has a network of seismometers, camera’s and other instruments in place. They provide real time seismic, photographic and other coverage of the volcanoes. Yesterday, just before the eruption, the GeoNet camera on White Island’s flank took an image that showed people on the crater floor perhaps 50-100 metres from the crater rim. The seismometer showed elevated activity that had been continuing for about three weeks was still happening. Last week a GeoNet statement said that it had entered a phase where an eruption should be considered possible.

Duty volcanologist for Institute of Geological and Nuclear Sciences (G.N.S.), which operate GeoNet, Brad Scott, has said that it is up to individual tour groups whether or not they operate from one day to the next. They operate through various alert levels. Hard hats, fully enclosed shoes and breathing masks are compulsory.

Over the next few days as the authorities piece together what happened, New Zealand will learn the story of how White Island caught authorities, tourist operators and locals alike off guard. But for now we focus on the survivors, those that are missing and those that were injured.

 

The Hikurangi Trench: New Zealand’s biggest tsunami hazard


Last night on the Seven Sharp programme, the hosts had a flat of young people in Napier City conduct and earthquake and tsunami evacuation drill. The earthquake, a fictional magnitude 8.9 on the Hikurangi Trench has triggered a tsunami and the occupants have 20 minutes to reach ground, with 60 seconds to get what they need and get out of the house. The objective immediately post earthquake was to get to Hospital Hill in a set period of time before a tsunami arrived.

The participants in the Seven Sharp drill did not quite make it. 2 young ladies and a young man had 60 seconds to decide what to take and get out of the house. They had to reach Hospital Hill about 2 kilometres away in the estimated 20 minutes they would have. They were out the door in a minute and were pretty sensible about what they took with them – something to stay warm, water and so forth and they had to carry it. Speed was of the essence, and at times despite the foot wear they were wearing, the ladies were running where they could.

One day there will be a substantial earthquake on the Hikurangi subduction zone. It will be anywhere between magnitude 8.5 and 8.9. It will last between 4-5 minutes and be felt the length and breadth of New Zealand. The above drill was aimed at Hawkes Bay, which will feel the full effect of the earthquake and be one of the first places to be hit by the tsunami – Gisborne and Wairarapa being next.

The biggest problem will not necessarily be the earthquake, although that will in itself be a massive event. Rather it is the tsunami risk that should cause people the most concern. From the subduction zone boundary to coastal Hawkes Bay is 110 kilometres. In the travel time of a tsunami that is about 20 minutes, possibly less.

One should not rely on the authorities to issue a warning in time. The warning system might well have been damaged in the earthquake. The people manning it might have injuries or other more immediate concerns such as making sure their headquarters is safe to occupy and getting the Emergency Operations Centre established in accordance with the Civil Defence and Emergency Management Act, 2002. During that time a tsunami heading for nearby coast lines would have a significant head start.

In a real event though, things will be about 10x tougher. We will assume that it is indeed at night time. When the shaking stops different people will react differently to the situation. A lot will be in shock and not thinking coherently. Before one can leave the house or building they are in to go inland they need to be able to safely clear a route and make sure all of their fellow occupants are safe. 1 minute would easily pass in that time – 4-5 minutes to get out might be more realistic. The power will most certainly be out in large parts of the city if not across the region so there will not be any working street lights, traffic lights or other lighting to guide them. There will be constant aftershocks and some might be substantial events in themselves. In a city built on marine sediments, liquefaction will have flooded many roads, which will also be cracked. Downed power lines, foot paths blocked with debris from buildings and trees pointing in crazy directions will also hinder progress. And if all that is not enough, there will most certainly be people who are – semi-understandably – panicking even though that is the worst thing one can do and trying to drive out despite the obstacles and potentially blocking others.

The tsunami will behave differently depending on several physical factors. For example the sea floor topography will help to determine the size and shape of the waves as they approach. Will they slow down gradually as they run up a fairly open and gently grading beach, where the classic waves that most associate with tsunami’s will form? Will they be coming up a narrowing bay that forces the waves to converge and become closely packed with short distances between them?

So, there you have it. Could those of you in a tsunami inundation zone find your way to high ground following a big earthquake?

Rejection of application to assess Franz Josef shows lack of understanding


The Minister for Regional Development Shane Jones has rejected an application to assess the suitability of Franz Josef for relocation. The rejection of the application, which came in the wake of destructive floods in March and growing concerns about its safety in an Alpine Fault earthquake, indicates a lack of understanding about the dangers posed to the popular West Coast township.

My main concern is that this will unnecessarily increase the risk to residents and visitors to the township. All residents and visitors have a right to be safe in the township during an emergency event, that structures and natural features have been subject to an E.I.M. assessment and matching appropriate steps have been taken:

  • E is ELIMINATE – ELIMINATE the hazard, whether it securing the parapets, chimneys of buildings to make sure they do not collapse onto the street or into adjacent buildigns
  • I is ISOLATE – ISOLATE is what gets done when a hazard cannot be eliminated, requires the separation of the hazardous feature and possibly a buffer zone around it to contain it if still dangerous
  • M is MINIMISE – MINIMISE the hazard if it cannot be ELIMINATED or ISOLATED, by diverting, removing or stopping all non essential functions/features/activities in the vicinity of the hazard

We cannot ELIMINATE the Alpine Fault and the Waiho River. We cannot ISOLATE their reach in Franz Josef’s current location. MINIMISING the risk by relocation off the probable area of the fault scarp and the active Waiho River bed is the best way of reducing the likely damage. The town would be immediately and violently subject to any Alpine Fault earthquake with massive disruption of power, water and sewerage, road and telecommunication links. A fault scarp possibly 2-5 metres high would rupture right through the township with 8 metres or more lateral displacement. The only thing therefore to do is either move all of the non-essential infrastructure of the township away from its current location and establish somewhere else or move the whole town. Neither option is going to be cheap and will probably result in having to buy up land somewhere.

One has to accept that there will still be considerable damage in Franz Josef even if it does get moved. However infrastructure will be far more quickly repaired. It will be spared the likely landslide dam burst emergency that would occur in the Callery River catchment immediately upstream of the Waiho River bridge. And most importantly it would be spared the massive ground damage that would be caused by the surface rupture and which alone would take months to begin to repair – if at all.

The ugly reality facing Franz Josef


Franz Josef is a picturesque town in Westland District. It is nestled against the lower flank of the Southern Alps, with the Waiho River immediately to the south of the township. The town and the nearby Franz Josef Glacier are named after the Austrian Emperor Franz Joseph, by explorer and geologist Julius von Haast.

But for all of its mighty charm nestled in temperate rainforest, Franz Josef is caught between a rock and a hard place. In terms of geological and geomorphological hazards it is in a location that in the long term, and increasingly likely in the short term, untenable. This article takes a look at the danger facing Franz Josef.

Why?

New Zealand straddles the boundary of two tectonic plates. To the west is the Indo-Australian Plate and to the east is the Pacific Plate. The onshore boundary is denoted by the Alpine Fault, a large fault line with a repose period of 300-350 years and a tendency to only move in magnitude 8.0+ earthquakes. The last one was about 1717AD.This onshore boundary is where about 25-30mm of tectonic uplift occur per annum as well as a similar amount of erosion, which means there is a continuous supply of sediment waiting to enter the catchments of the West Coast and east coast rivers.

This relentless uplift creates a lovely mountain range with steep hydrology – from the summit of Mt Cook to the Tasman Sea is about 45 kilometres. Being in the prevailing westerly belt of winds that sailors call the “Roaring Forties” because of the latitude, moist westerly air comes off the Tasman Sea and empties its moisture content – often over 200 millimetres and up to 500 millimetres in a day – on the West Coast side. Unsurprisingly flooding becomes a major problem.

How does this affect Franz Josef?

Immediately after one crosses the Waiho River heading south, the road takes a hard right turn. In the corner is a hotel that sits behind a substantial stop bank. On the other side of that stop bank is a riverbed that is rising at a rate of about 300mm each year. The rise is because a large volume of sediment is continually entering the Waiho catchment. This poses an increasing flood risk on a river where water levels start responding to heavy rain in less than an hour.

Franz Josef straddles the Alpine Fault, which runs right through the middle of the township. It crosses the Waiho River in the immediate vicinity of the Milton Hotel, which was flooded and suffered severe damage in a 2016 outbreak. Westland District Council published Plan Change 7 (P.C.7), which was meant to identify a zone through central Franz Josef, where there is high confidence of the Alpine Fault’s exact location, with a view to moving essential services and businesses out of the zone. However after considerable public opposition, P.C.7 was scrapped.

When?

Time is running out. The stop bank is about as tall as it can realistically get without massive supporting earth works. When the river tops it, it will start eroding away the stop bank and try to reclaim the riverbed that the stop bank was originally built over. This may claim several farms when it happens.

But there is a bigger problem. The Alpine Fault is now due for another earthquake. Should it rupture whilst Franz Josef is in its current location, the town will be subject to immediate and unmistakably violent shaking lasting up to 3 minutes. There will be between 8-10 metres lateral displacement to the right and up to 3 metres vertical displacement. Only the newest structures would probably be still standing.

Before then though, there may be another rain storm of similar magnitude to the one that occurred between 25-27 March. Should that happen, similar damage to what happened as a result of that storm should be expected. This has a high probability of including the bridge over the Waiho River, which was destroyed on Tuesday 26 March. The next rain fall event might not even need to be that big.

What is the solution?

In the absence of P.C. 7 existing, one option is to give up on the stop bank and let the Waiho River reclaim the riverbed. The problem here is that several farms and the air field would have to move. It also does not address the long term problem of the Alpine Fault. Perhaps the most feasible option is progressively relocate Franz Josef township’s population and amenities to neighbouring towns. Westland District Council and West Coast Regional Council have a duty of care to the residents and the tourists and other visitors to their District/Region to make sure that they are in no undue danger.

Where could the people go?

There are several nearby townships where the people of Franz Josef could be moved to. Ross and Whataroa are two, though these are quite near the Alpine Fault. Harihari is a third. All are on the same road, State Highway 6, as Franz Josef. It would be likely that West Coast Regional Council and Westland District Council would need to prepare a joint request for Government assistance purchasing land and working out appropriate resource management issues.

For their part the Government would most likely need to provide assistance. The West Coast is economically one of the poorer parts of New Zealand. It has a small rate payer base and this has a good chance, even if well planned and executed, of blowing whatever budget is set. And if the plan went ahead, it might have to be applied to Fox Glacier as well, as it too is very near the Alpine Fault.