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.

 
 
 
 

To boost the high street, cities should invest in offices

Offices in Northampton. Image: Getty.

Access to cheap borrowing has encouraged local authorities to proactively invest in commercial property. These assets can be a valuable tool for cities looking to improve the built environment they offer businesses and residents.

Councils are estimated to have spent £3.8bn on property between 2013 and 2017, funded through the government’s Public Works Loan Board (PWLB) at very low interest rates. Offices accounted for half of this investment, and roughly a third (£1.2bn) has been spent on retail properties. And local authorities were the biggest investor group for UK shopping centres in the first quarter of 2018.

Why are cities investing? There are two major motivations.

First, at a time when cuts are squeezing council revenue budgets, property investments can provide a long-term revenue stream to keep quality public services up and running. Second, ownership of buildings in areas marked for redevelopment allows councils to assemble land more easily and gives them more influence over the changes taking place, allowing them to make sure the space evolves to meet their objectives.

But how exactly can cities turn property ownership into successful place-making? How should they adapt the buildings they invest in to improve the performance of the economies?

Cities need workers

When developing the city’s property offer, the aim should be to get jobs back into the city centre while reducing the dominance of retail space. For councils who have invested in existing retail space and shopping centres, in particular, the temptation may be to try and retain their existing use, with new retail strategies designed to reduce vacancies.

But as the Centre for Cities’ recent Building Blocks report illustrates, the evidence points to this being a dead-end. Instead, cities may need to convert the properties they own so they house a more diverse group of businesses.

Many city centres already have a lot of retail – and this has not offered significant economic benefit. Almost half (43 per cent) of city centre space in the weakest city economies is taken up by shops, while retail only accounts for 18 per cent of space in strong city centre economies. And many of these shops lie empty: in weaker city centres vacancy rates of high-street services (retail, food and leisure) are on average 16 per cent, compared with 9 per cent in stronger city economies. In Newport, nearly a quarter of these premises are empty, as the map below shows.

The big issue in these city centres is the lack of office jobs – which are an important contributor to footfall for retailers. This means that, in order to improve the fortunes of the high street, policy will need to tackle the barriers that deter those businesses from moving to their city centres.

One of these barriers is the quality of office space. In a number of struggling city centres, the quality of office space on offer is poor. But the low returns available for private investors mean that some form of public sector involvement will be required.


Ownership of buildings gives cities the opportunity to reshape the type of commercial space on offer. Some of this will involve improving the existing office stock available, some will involve converting retail to office, and some of will require demolishing part of the space without replacing it, in the short term at least. Without ownership of the land and buildings on it, this task becomes very difficult to do but will be a fundamental part of turning the fortunes of a city centre around.

Cheap borrowing has provided a way not only for local authorities to generate an income stream through property investment. but also opens up the opportunity to have greater control over the development of their city centres. For those choosing to invest, the focus must be on using ownership to make the city centre a more attractive place for all businesses to invest, rather than hoping to revive retail alone.

Rebecca McDonald is an analyst at the Centre for Cities, on whose blog this article first appeared.