Lava in Hawai'i is creating new land. It also might kill you

Lava flows from Kīlauea. Image: EPA.

There is something special and awe-inspiring about watching new land form. This is what happened recently in Hawai’i as its Kīlauea volcano erupted. Lava is reaching the ocean and building land while producing spectacular plumes of steam. These eruptions are hugely important for the creation of new land. But they are also dangerous. Where the lava meets the ocean, corrosive acid mist is produced and glass particles are shattered and flung into the air. Volcanic explosions can also hurl lava blocks hundreds of metres and produce waves of scalding hot water.

At Kīlauea, lava is erupting from a line of vents on the volcano’s flanks, and is moving downslope to the edge of the island, where it enters the ocean. This is a process that has been witnessed many times at Hawai’i and other volcanic islands. And it is through many thousands of such eruptions that volcanic islands like Hawai’i form.

The new lava being added to Hawai’i by this latest Kīlauea eruption replaces older land that is being lost by erosion, and so prolongs the island’s lifespan. In contrast, older islands to the north-west have no active volcanoes, so they are being eroded by the ocean and will eventually disappear beneath the waves. The opposite is happening to the south-east of Hawai’i, where an underwater volcano (Lōʻihi Seamount) is building the foundations of what will eventually become the next volcanic island in this area.

How lava gets to the ocean at Hawai’i

The lava erupting from the current Kīlauea vents has a temperature of roughly 1150 degrees °C, and has a journey of between 4.5km and 5.5km to reach the ocean. As this lava moves swiftly in channels, it loses little heat and so it can enter the ocean at a temperature of over 1000 degrees°C.

When lava meets the sea, new land is formed. Image: EPA.

What happens when lava meets the ocean?

We are witnessing one of the most spectacular sights in nature - billowing white plumes of steam (technically water vapour) as hot lava boils seawater. Although these billowing steam clouds appear harmless, they are dangerous because they contain the small glass shards (fragmented lava) and acid mist (from seawater). This acid mist known as “laze” (lava haze) can be hot and corrosive. If anyone goes to near it, they can experience breathing difficulties and irritation of their eyes and skin.

Apart from the laze, the entry of lava into the ocean is usually a gentle process, and when steam is free to expand and move away, there are no violent steam-driven explosions.

But a hidden danger lurks beneath the ocean. The lava entering the sea breaks up into blobs (known as pillows), angular blocks, and smaller fragments of glass that form a steep slope beneath the water. This is called a lava delta.

A newly formed lava delta is an unstable beast, and it can collapse without warning. This can trap water within the hot rock, leading to violent steam-driven explosions that can hurl metre-sized blocks up to 250 metres. Explosions occur because when the water turns to steam it suddenly expands to around 1,700 times its original volume. Waves of scalding water can also injure people who are too close. People have died and been seriously injured during lava delta collapses

So, the ocean entry points where lava and seawater meet are doubly dangerous, and anyone in the area should pay careful attention to official advice on staying away from them.

Pillow Lavas form underneath the ocean. Image: National Oceanic & Atmospheric Adminstration (NOAA).

What more can we learn from these eruptions?

Once lava deltas have cooled and become stable they represent new land. Studies have revealed that lava deltas have distinctive features, and this has enabled volcanologists to recognise lava deltas in older rocks.

Remarkable examples of lava deltas have been discovered near the top of extinct volcanoes (called tuyas) in Iceland and Antarctica. These deltas can only form in water and the only plausible source of this water in this case is melted ice. This means that these volcanoes had melted water-filled holes up to 1.5km deep in ice sheets, which is an astonishing feat. In fact, these lava deltas are the only remaining evidence of long-vanished ice sheets.


The ConversationIt is a privilege to see these incredible scenes of lava meeting the ocean. The ongoing eruptions form part of the natural process that enables beautiful volcano islands like Hawai'i to exist. But the creation of new land here can also bring danger to those who get too close, whether it be collapsing lava deltas or acid mist.

Dave McGarvie, School of Physical Sciences, The Open University and Ian Skilling, Senior Lecturer (Volcanology), The University of South Wales.

This article was originally published on The Conversation. Read the original article.

 
 
 
 

It’s time to rethink how the British railway network works

Nothing doing: commuters await a long-delayed train. Image: Getty.

The recent meltdowns on Northern and Thameslink not only left many passengers besides themselves with frustration about not being able to get to work on time, if at all. It also led to a firestorm of criticism and condemnation from politicians and media alike.

With the immediate shock of that first Monday morning of the meltdown passed, there’s a now a bigger debate about whether the way that rail services are provided for cities needs some far reaching reform. But before coming to that, the first thing to say – and as we set out in our Rail Cities UK report, launched today – is that the fundamentals for urban rail remain very strong.

Here’s why. All cities want to become denser, more dynamic places which attract the best people to the growth sectors of the economy (including the ‘flat white economy’ of media, communications and information). In order to achieve this, as well as to improve air quality, cities are also reducing space for motorised traffic in favour of space for people.

It’s very difficult to see how this can be achieved without expanding rail networks and their capacity. What’s more, if housing need is to be met without creating more sprawl and traffic congestion, then again its rail that will be key – because it opens up former rail-connected brownfield industrial sites, it extends commuting range, plus housing can be built above or around new or existing rail stations and interchanges.

In some ways there’s nothing new here. From Metroland to Docklands, successful cities have always grown with their rail networks. And to be fair, there is significant investment going into urban rail at present. Northern will get a lot better (the pacers are doomed) and both Merseyside and Tyne & Wear are getting a whole new fleet of trains for their urban rail networks.

However, much (but not all) of this investment is incremental, or replacing rolling stock on its last legs. It stops short of the wider vision for the rail cities that we need.


What would that look like in practice? There comes a point when the biggest cities need more cross-city routes, because running trains in and out of edge-of-centre termini can’t cope with the numbers. That explains the push for Crossrail 2 in London, but also the need for more cross-city capacity in cities like Birmingham (on the Snow Hill route) as well as in Manchester (on the Oxford Road to Manchester Piccadilly corridor, as well as a potential new underground route).

Tram-train technology can also help – allowing the lucky commuter that benefits to get on board at their local station and get off right outside their city centre office on main street in the city centre, rather than piling out at a Victorian railway terminal on the edge of that city centre.

Tram-trains aren’t the only tech fix available. Battery packs can extend the range of existing electric trains deeper into the “look ma, no wires” hinterlands, as well as allow trams to glide through city centres without the expensive clutter of overhead wires.

More mundane but equally useful work to increase capacity through signalling, station, track and junction work offers the opportunity to move to turn-up-and-go frequency networks with greater capacity and more reliability – networks that start to emulate the best of what comparable German rail cities already enjoy. Interlocking networks of long distance, regional express, regional, S-bahn, U-bahn, trams and buses, all under common ticketing.

But in talking about Germany and common ticketing I am now getting back to where I started around the debate on whether some fundamental change is needed on how urban rail networks are provided. Obviously there is a bigger national discussion going on about whether the current structure is just too layered, with too many costly interfaces and too fractured a chain of command. And in addition another, on whether the railway should be publicly or privately owned and operated.

But it’s been heartening to see the growing recognition that – regardless of how these debates are resolved – more devolution for urban and regional services should be part of any solution. That’s not only because fully devolved services have been out-performing comparators both operationally and in passenger satisfaction; it’s because local control rather than remote control from Whitehall will mean that the dots can be joined between rail and housing, between rail and the wider re-fashioning of city centres, and between rail and local communities (for example through repurposing stations as wider hubs for local community use, enterprises and housing). It will also allow for rail and the rest of local urban public transport networks to be part of one system, rather than be just on nodding terms as is all too often the case at present.

The crisis on Northern and Thameslink has been a miserable experience for rail users, affected cities and the rail industry. If any good has come out of it, it is that it shows how important rail is to cities, and opens up a space for some bigger thinking about what kind of rail cities we will need for the future – and how best we can make that happen.

Jonathan Bray is the Director of the Urban Transport Group which represents the transport authorities for the largest city regions. You can read the group’s full report here.