Kilauea's lava has been flowing for 35 years — what's science learning from the latest eruption?

Gushing ash clouds, belching boulders, oozing lava - it's business as usual for the Kilauea Volcano in Hawaii.

Kilauea is a Hawaiian word meaning "spewing", which is a fitting name for a young volcano that's been active for most of recorded history.  Scientists date it back 600,000 years, but 90 per cent of its surface is covered in lava less than 1000 years old, which means it's been working hard in the past millennium to beef itself up. Kilauea has erupted 61 times since record-keeping began in 1823, making it one of the most active volcanoes on Earth.

On January 3, 1983, it started its 62nd eruption. A volcanic cone, called Puʻu ʻŌʻō, opened up 20 kilometres east of the main caldera, and has been bubbling and spewing ever since. Over the past 35 years it's rotated between predictable steady eruptions and more chaotic events, including a devastating outburst in 1990 when it buried the nearby town of Kalapana under 24 metres of lava.

35 years makes it the longest volcanic eruption in the past two centuries, and because of this, scientists like Dr. Mike Poland have been using it as a living laboratory to study how volcanoes work. Poland is a USGS geophysicist who studied Kilauea for more than a decade. "One thing that is impressive about Kilauea is the intense monitoring network that has been existing on the volcano for the last few decades. There's a tremendous network of seismometers and GPS stations and tilt meters and other equipment that's on the ground."

Which is how, a few weeks ago, Dr. Poland and his fellow researchers were able to watch in real time as Kilauea geared up for another outburst.

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"We had a pretty good idea that something was going to change at Kilauea because we started to see inflation of both the eruptive vent, the Puʻu ʻŌʻō vent where lava had been coming out of the ground, as well as inflation at the summit" said Dr. Poland.

Inflation in a volcano is caused by pressure building up underground. It happens frequently at Kilauea. "We sort of imagine that the plumbing system is much like the plumbing system in the house. All of these areas, these vents are interconnected. So when something starts backing up in one part of the plumbing system you can see pressure increase in other places."

On April 30, the floor of the Puʻu ʻŌʻō crater collapsed, and the lava lake inside disappeared. Two days later, the lava lake at the summit also flowed out. Typically, this means a new vent is opening up somewhere nearby. But this time that didn't happen. Instead, the lava had pushed past a blockage in the plumbing, and shot through the underground conduits for 20 kilometres, bursting through the earth in several fissures near a community called The Leilani Estates, destroying 37 homes and forcing the evacuation of thousands of people.

While the losses to property are devastating, for scientists like Dr. Poland, it means they can get a look into a whole new part of Kilauea's plumbing that they couldn't see before.

"What we're seeing now is essentially a new opportunity to use all of this new monitoring data to really map out the plumbing system in great detail and I think understand hopefully better some of the mechanisms for why these weak links break and where they may be located."

Dr. Poland, who is now Yellowstone's Scientist-In-Charge, isn't on the ground in Hawaii. But he's still helping to map out this event using satellite imagery to look at how the earth is deforming, and using thermal imaging to see where the lava is flowing - both above, and below the surface. 

Meanwhile, his colleagues on the ground are collecting lava to paint a picture of where it comes from. To do this, they have to get close to the action, and physically scoop up lava from the front of the flow. Early results from this outburst showed the lava was of a similar makeup as from Kilauea's 1955 eruption, so it had likely been sitting near the top of the volcano for quite some time. Now, the lava is coming from much deeper underground.

Contrary to most people's expectations, lava isn't the biggest safety concern here.  "Hawaiian eruptions are things that can mostly be walked away from. There's not a tremendous amount of danger being close to lava flows. In fact the lava flows in Hawaii have been tourist attractions for a very long time," said Dr. Poland.

But, he adds, what is dangerous is the noxious gas that's often spurting out alongside the lava, as well as chemical reactions when the molten magma interacts with things like water or vegetation. "The vegetation is wet. So there's some water that flashes to steam but also as the vegetation combusts it releases methane and that methane tends to accumulate beneath the flow. And can suddenly explode outward."

"There's also some explosive activity occurring at the summit as the lava lake withdrew. As that draws down it allows groundwater to infiltrate the area where the lava was and when that water comes in contact with hot rock it creates explosions that can send boulders flying several hundred meters away. And we're seeing that activity at the summit along with the generation of some volcanic ash as well."

Dodging ballistic boulders the size of microwaves is nothing new for Dr. Poland, and the geologists currently on the ground at Kilauea. They're hoping that this new, bigger picture of Kilauea's plumbing will help them learn even more about these explosive events, and how to predict when and where they'll pop up next.

"What's going on now is hopefully going to teach us an awful lot about the volcano and it's an important opportunity that we can't waste, especially at the cost of this event in terms of people that have been concerned and lost homes and have their livelihoods threatened."

Aerial images taken by the USGS show how the Kilauea eruptions are changing the landscape of the Big Island