′Don′t expect Kilauea to finish anytime soon′ | Science| In-depth reporting on science and technology | DW | 28.05.2018
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'Don't expect Kilauea to finish anytime soon'

Hawaii's dramatic ongoing eruption has many wondering about the future for locals on Big Island. Seismologist Jessica Johnson talks to DW about blue flames, vog and laze, and what she'd do if she could go there now.

DW: What's new about this Kilauea eruption?

Jessica Johnson: The main differences are that, this time, it's in a residential area. This time we have fissures opening on residential roads, lava flows going across people's houses. So the impact from this particular eruption is quite different. The other difference we have is that the lava lake, which is at the summit—or was at the summit—has lowered. The magma has withdrawn so much that it's now below the water table. And that means that the interaction of water and magma can cause explosions at the summit, which we've not seen since 1924.

How large would those explosions be?

Well the largest one we've had so far, I believe, sent ash up to about 9 kilometers (5.6 miles) into the atmosphere. Some of the more recent ones, we've been seeing them sending ash three or four kilometers into the atmosphere. So they're fairly sizable. They definitely have an effect on air traffic, but because the summit is not a residential area—it's inside the national park—there aren't many people who are being impacted by those explosions. But the ash created from those explosions is impacting people who live downwind of the volcano.

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I've been hearing some new words as a direct result of the Kilauea eruption - terms like "vog" and "laze." What are they, and just how dangerous is it to breathe Hawaiian air right now?

So "vog" is volcanic fog that usually consists of sulfur dioxide, which is emitted from the lava as it erupts. Sulfur dioxide in the air is toxic. You can definitely kind of smell it and taste it if you're exposed to it in small amounts. Or in large amounts it can make breathing quite difficult, it can sting your eyes, and it can also cause kind of corrosion when it mixes with water and makes an acid. "Laze" is a mixture of the word lava and haze. It's a product of the lava, but in this case the lava, when it meets the ocean, causes a chemical reaction and causes tiny droplets of hydrochloric acid in combination with tiny particles of volcanic glass. So because the lava is meeting the water, it can cause very small explosions, where it's turning the water into steam. And these particles get pushed up by the heat and cause a haze, which is made up of hydrochloric acid particles and volcanic glass. So that, again, is very toxic. It's very dangerous to breathe, and in fact in I think it was in 2000 that two people did actually die from being exposed to a large pocket of laze.

Lieutenant Aaron Hew Lew, of the Hawaii National Guard, measures levels of toxic gas near a lava flow in the Leilani Estates subdivision

The Hawaii National Guard constantly measures levels of toxic sulfur dioxide gas near a lava flow

What should people do if they're confronted with vog, laze or ash?

The recommendation is to stay inside keep your windows closed. If you're driving, you can keep your windows closed—particularly if you're driving an ash. Pull over somewhere safe and just wait for the hazard to pass, because it can limit visibility. It can cause slippery roads as well.

One video from Kilauea showed something… I thought it was actually fake. There were dark blue flames burning on top of the charred landscape. What's going on there?

When the lava flows over vegetation, the vegetation burns, but it doesn't have access to the oxygen, and the gases aren't allowed to escape. So it actually creates methane, and that methane escapes by going down into the ground cracks. And it follows some pathways under the ground, so that the methane is able to escape through other ground cracks that haven't been covered by lava yet. And obviously they're very, very hot and catch fire. So those blue flames are actually methane that's being created from vegetation that's been overtaken by lava.

Lava from Kilauea starting to consume the house in Pahoa, Hawaii.

Thousands of residents have already been evacuated from endangered areas

What do vulcanologists expect Kilauea to do next?

The fact that there are still small earthquakes happening, and that there are still ground deformations, tells us that there's still magma being supplied to the Lower East rift zone. So we don't expect this eruption to finish anytime soon. The other thing that we do is we look for past patterns to see if we can see similarities as to what the volcano might do next—so the past eruptions have happened in the Puna area. One of them lasted several weeks. The other one lasted a couple of months. So we were sort of thinking that that might be a reasonable timescale. But at the same time, we've seen eruptions that have lasted just a couple of days up to the Puʻu ʻŌʻō eruption, which is halfway up the rift zone, that has lasted for 35 years. So it's definitely not an exact science.

Jessica Johnson, vulkanische Seismologin (Privat)

Jessica Johnson at the site of a lava ocean entry

If you could fly to Kilauea right now, what would you want to see, or do, or research there? Is there anything that's absolutely novel?

Absolutely. As a seismologist, the fact that we're having these earthquakes down in the Lower East rift zone is really interesting for me, because that's usually a fairly seismically quiet zone. The fact that we've got earthquakes there will really allow us to image the subsurface. So I actually have written a grant to try and get money to go to Hawaii right now to put out some more seismometers and try and capture that data so that we can we can create better images on the ground in that area.

Jessica Johnson is a volcano seismologist and a lecturer at East Anglia University in solid earth geophysics.


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