Why does smooth pāhoehoe lava suddenly change to crystal-filled ‘a’ā lava? A new theory.

 When water flows down a gradual stream over a generally flat bottom, it’s clear and transparent, but when it hits a steep slope like rapids and waterfalls, it turns white and frothy.

Still wet, but very different.

Similarly, newly-erupted molten volcanic rock flows smooth and sinuous as pāhoehoe lava, and then sometimes changes to an entirely different look, broken-up, chunky, rough ‘a’ā lava.

We know what’s causing the water to change—turbulence and increased speed. But what’s happening with molten rock?

A team of Stanford researchers think they have an answer. They are Cansu Culha, Sam Spinner and Jenny Suckale, and in May 2023 Geophysical Research Letters published their theory under the title, “The Yih Instability in Layered Lava Flow May Initiate the Pāhoehoe to ‘a‘ā Lava Transition.”

You find both kinds of lava at volcanoes everywhere there are basalt-erupting volcanoes, whether the Hawaiian volcanoes or those erupting through the snows of Iceland.

Most lava flows start as pāhoehoe, and then occasionally some of them suddenly change form. Instead of flowing like water down a quiet river, they change dramatically. You can even hear the change, as the ‘a’ā tinkles and pings like broken glass as it tumbles rather than flows downslope. And ‘a’ā has far more crystals in it.

The change in form, the authors write, is a big deal to volcano scientists: “These fundamental differences in flow characteristics have made understanding the transition a classic question in volcanology.”

Others have suggested that turbulence may be a factor, that if you stir up pāhoehoe, it will change to ‘a’ā. 

But how does that happen? How does smooth, internally blended lava change to rough crystalline lava?

The authors looked to the work of Chia-Shun Yih, who in 1967 wrote a seminal paper on fluid dynamics. Yih noted that when there are different viscosities in a moving liquid—meaning they flow more or less easily—that can cause instability in the fluid. That concept is now called Yih Instability.

When a lava flow starts as pāhoehoe, over time, the surface is exposed to cooler air and starts to harden. And so, soon, there is molten rock flowing at different rates of speed within the same flow.

“A key assumption in our model is that pāhoehoe flows may have internal layers,” the authors write.

And that difference between layers can cause instability, which can provoke the change from smooth lava to rough chunky lava, they propose.

But it’s complicated.

Sometimes a change in speed can prompt ‘a’ā transformation, like when pahoehoe flows over a cliff. But not always.

Sometimes just a fast-moving flow down a steep slope can prompt the change. But not always.

And sometimes, a hardened surface appears to protect the still-moving lava below from making the change. That might be what happens in a lava tube—when the surface has hardened over, and the pahoehoe lava beneath can flow long and fast without the internal viscosity layers.

With Kīlauea erupting again, the new suggestions provide volcano scientists with new ways of looking at what’s going on.

If you’re interested in a less complex review of the data than is in the Geophysical Research Letters piece, Maya Wei-Hass has a review in the journal Science, under the title “Lava comes in two flavors…”

© Jan TenBruggencate 2023

Can sea level change promote volcanic activity in Hawai'i? This theory suggests it can.

 There’s this odd thing about Hawaiian volcanic activity—secondary volcanism.

This is the appearance of new eruptions long after the main island-building volcanic activity is done. It is also called rejuvenated volcanism.

Think Diamond Head on O’ahu, Lehua Island off Ni’ihau, and all the cinder and tuff cones around Koloa on Kaua’i, which are clearly different-looking than the landscape around them. And which date much, much younger than the lavas around them.

Why does that new lava suddenly force its ways through million-year-old rock? Traditionally, there are three theories, and rather than going through them here, you can check out Volcano Watch. 

Now a team of geologists from Hawai’i, Wisconsin and the United Kingdom have proposed an intriguing additional reason: dramatic sea level change.

The new report published by the Geological Society of America was written by Brian R. Jicha of the University of Wisconsin-Madison, Michael O. Garcia of the University of Hawai’i, and Charline Lormand of Durham University in the UK. It is entitled, “A possible sea-level fall trigger for the youngest rejuvenated volcanism in Hawaiʻi.”

(Citation: Jicha, Brian R., Michael O. Garcia, and Charline Lormand. "A possible sea-level fall trigger for the youngest rejuvenated volcanism in Hawaiʻi." GSA Bulletin (2023).)

Garcia makes the point that this is not an alternative but an additional theory, and that different rejuvenated volcanic activity might be associated with different mechanisms.

One of their key pieces of evidence, at volcanic hot spots around the globe, is that when sea levels have fallen significantly, geological dating shows that oceanic volcanoes have erupted in this kind of late stage volcanic activity.

During a period 350,000 years ago, sea levels dropped 300 feet below current levels—and there were corresponding eruptions on Kaua’i, Molokai and Ascension Island in the South Atlantic.

When sea levels dropped about 200 feet about 225,000 years ago, there was volcanic activity on Kaua’i.

When they dropped nearly 300 feet 150,000 years ago, volcanoes erupted on Kaua’i and in Samoa.

When they dropped 300 feet about 60,000 years ago, there were eruptions at Ascension Island, Fogo in the Cape Verde Islands, and on O’ahu. The O'ahu eruptions were at Tantalus on O’ahu and in a region called the Koko Rift.

(A caveat: Volcanoes don't always respond this way. There was another low sea level period about 25,000 years ago, when Fogo, Samoa and Tristan de Cunha in the South Atlantic erupted, but Hawaiian volcanoes apparently didn’t engage in rejuvenated volcanism. And there was an unusual Kaua’i eruption about 320,000 years ago when sea levels were comparatively high, which doesn’t follow the trend.)

This kind of volcanic activity seems less likely to occur when sea levels are high. But they do when it’s low. The theory is that lower sea levels create stresses in the earth’s crust, and those let the magma force its way into dikes and sometimes to the surface. 

“Numerical modeling indicates that when sea level falls 40 m (40 meters, or about 120 feet) below the present-day level, the induced tensile stresses trigger dike injections. If sea level continues to fall to -70 or -90 m (210-270 feet) the induced tensile stress is inferred to allow dikes to reach the surface and erupt,” the researchers wrote.

They did extensive work on the Koko Rift, an 18-kilometer line of volcanic activity that runs an axis from Koko Head and Koko Crater across the Ko’olau ridge to Kāohikaipu Island off Makapu’u. All the several volcanoes along that line erupted about the same time, roughly 67,000 years ago: “The Koko Rift eruptions are analytically indistinguishable in age,” they wrote.

The Koko Rift volcanics are also the most recent examples of secondary or rejuvenated volcanism in Hawai’i—younger than the cinder or tuff cones elsewhere on O’ahu or on the other islands.

There have been other suggested explanations for secondary volcanic activity, but this one seems to be a good fit.

“Oscillations in sea level were recently recognized as a potential key mechanism for modulating volcanism by causing crustal stress from loading and unloading in ocean regions,” they wrote.

The low sea level periods are associated with ice ages—periods when vast amounts of the planet’s water is locked up in ice caps, glaciers and snow fields.

Certainly, sea levels aren’t the only cause of eruptions, and as mentioned earlier, there are cases of rejuvenated volcanism outside low stands of the sea. 

And there is certainly plenty of eruptive activity during high sea level periods now, including the ongoing Kīlauea eruption, the recent Mauna Loa eruption, historic eruptions at Kama’ehuakanaloa (formerly Lō’ihi), Hualālai and Haleakalā, and a possible 1956 eruption in the Ka’ie’ie Channel between Kaua’i and O’ahu.

The authors of the rejuvenated volcanism paper concluded: “Future investigations of rejuvenated volcanism in Hawai‘i and globally should also consider the long-term influence of the Earth’s climate system on magmatic processes to better infer past and future eruptive behavior.”

It is also true that advances in science are driving new revelations, Garcia said in an email: "We are continuing to better understand secondary volcanism with an ongoing study of the age and geochemistry of Honolulu lavas. One might think that after more than 100 years of studying these lavas that we would fully understand them but new, more precise analytical methods are allowing us to gain a better understanding."

© Jan TenBruggencate 2023

 

The volcanoes: Kīlauea reinflating, Mauna Loa resting

Two weeks after their double eruption, Kīlauea and Mauna Loa are handling the holidays differently, although neither is erupting.

Mauna Loa appears to be resting, according to the U.S. Geological Survey’s Hawaiian Volcano Observatory.

At Mauna Loa, “deformation rates have decreased significantly, and there is no sign of inflation at this time. The Hawaiian Volcano Observatory continues to closely monitor the earthquake and deformation rates at Mauna Loa. We expect additional shallow seismicity and other signs of unrest to precede any future eruption, if one were to occur,” the observatory reported.

At Kīlauea, there is more activity. Seismologists’ instruments show that Kīlauea is re-inflating, its upper area expanding as magma pumps into underground chambers near the surface.

The smaller mountain has been inflating since November 29—meaning it was inflating at the same time it was erupting during the early days of the Mauna Loa eruption. A seismic swarm, indicating magma movement underground, shook the volcano Friday (December 30).

“These earthquakes are typical as the summit of Kīlauea repressurizes after the end of the last eruption.  The earthquakes are generally dispersed beneath and around the south side of Halemaʻumaʻu,” the HVO reported.

It is normal for Mauna Loa to take a longer break between eruptions than Kīlauea.

Kīlauea’s most recent eruption lasted a little more than 14 months from September 29, 2021, to December 9, 2022. It was entirely within the crater at Halema’uma’u. The volcano erupts frequently, often a couple of times a year, and sometimes continuously for years.

Mauna Loa’s recent eruption lasted from November 27, 2022, to December 10, 2022. The volcano for the past couple of centuries has erupted every five years or so, but pauses between eruptions can be months to decades long.

© Jan TenBruggencate 2022

Keeling Curve, key climate change measure, restored after Mauna Loa flow interuption

 

The Keeling Curve is back, after a brief volcanic interlude.

The world’s longest-running measurement of changes in carbon dioxide in the atmosphere is collected at a small observatory some 11,000 feet high on the slopes of Mauna Loa. It’s been tracking the changes since 1958, when Charles Keeling started taking the measurements.

The 2022 eruption of Mauna Loa sent a flow across the observatory access road and interrupted the Mauna Loa Observatory’s ability to operate on November 29. As the lava cooled, service was restored in mid-December.

(Images: The top image for the past month shows the interruption in the data. The image immediately above shows the full Keeling Curve, since 1958. Both are courtesy of Scripps Institution of Oceanographty at UC San Diego. Bottom image of the Mauna Loa Observatory is courtesy of NOAA.)

It’s not the first time Madame Pele has interfered with the science. She also did it in the 1984 Mauna Loa eruption.

“It’s in a bad place,” said Ralph Keeling, a geoscientist with Scripps Institution of Oceanography at the University of California San Diego. Ralph is Charles Keeling’s son.

A bad place from a volcanic risk view, but an excellent place for its unique kind of measurement—gathering atmospheric gas changes in the mid-pacific at an elevation high above most of the dust and pollutants of cities and streets.

The Keeling Curve has been a key scientific data point in the discussion of climate change, since carbon dioxide is one of the key atmospheric gases associated with the warming of our planet.

The observatory is operated by the National Oceanic and Atmospheric Administration.

The latest Keeling reading, Christmas Day 2022, was 419.25 parts per million CO2 in the atmosphere. That’s 50 percent higher than the level during the start of the Industrial Revolution in the 1800s, and more than 100 points higher than when Keeling first started taking measurements in 1958.

See the actual Keeling Curve measurements and read about the history of the measurement here. 

Yeah, and if you add CO2 data from ice cores, that 419.25 is higher than any Christmas since the first Christmas, and indeed, higher than any time in the last 800,000 years. This doesn't bode well.

© Jan TenBrugggencate 2022

Volcanic mystery solved: Mauna Loa and Kīlauea are connected 25 miles under Pāhala

 One deep mystery about our Hawai’i volcanoes has been solved.

The mystery was this: Do Mauna Loa and Kīlauea have independent connections to the hot rock in the Earth’s mantle, or do they share a magma reservoir nearer the surface.

Now, we know it’s the latter.

That’s due to a detailed study, reported in the December 22, 2022, issue of the journal Science. The study used artificial intelligence/machine learning to make sense of 3-D imagery of the locations of nearly 200,000 recent earthquakes under Mauna Loa and Kīlauea.

The study is entitled “The magmatic web beneath Hawai‘i.” It was written by John D.Wilding, Weiquiang Zhu, Zachary Ross and Jennifer Jackson. 

All of Hawai’i’s volcanoes are ultimately fed from the planet’s mantle, which is hundreds to a couple of thousand miles below the surface. They are fed by a phenomenon that has been called a Hot Spot, which drives molten rock from the deep mantle through cracks in the Earth’s crust, eventually to the surface.

The seismic study found that there is a magma storage area about 25 miles down, roughly under the Hawai’i Island town of Pāhala.

It takes the form of a series of horizontal structures, like stacked plates. These plates are roughly 3-4 miles wide, 1,000 feet thick, and vertically separated by about 1,500 feet of rock. The researchers call it the Pāhala sill complex.

From there, independent channels lead to the summit of Mauna Loa and the top of Kīlauea. The Mauna Loa channel is comparatively direct, while the Kīlauea channel goes laterally for a while, then rises to what looks like a secondary magma storage area 6-9 miles under the Kīlauea summit.

These channels are identified in the research as “seismicity bands,” which are areas, when mapped in 3-D, that show the location of pathways where magma may be moving.

So, yes, it looks like the two volcanoes are connected. But the magma feeding the two of them comes from different parts of the Pāhala sill complex, far enough apart that they sometimes seem to act independently.

So what about the newest Hawaiian volcano, Kama’ehuakanaloa (formerly Lō’ihi)? It does not seem to share the Pāhala sill complex, and appears to have its own route from the mantle, the authors write.

Star-Advertiser reporter Timothy Hurley’s review of the study here. 

National Geographic’s report on the study is here. 

© Jan TenBruggencate 2022

Eruption over, both Kīlauea and Mauna Loa pau

 

The storied double eruption of Kīlauea and Mauna Loa is over, with the official notice today, December 13, 2022, that both eruptions have stopped.

The cessation was not quite simultaneous, but close.

The Hawaiian Volcano observatory has moved both volcanoes off its orange alert level to yellow, and has issued these relevant statements:

“Kīlauea is no longer erupting. Lava supply to the Halemaʻumaʻu lava lake ceased on December 9 based upon lava lake levels and behavior of the crater floor. Sulfur dioxide emissions have decreased to near pre-eruption background levels.” 

“Mauna Loa is no longer erupting. Lava supply to the fissure 3 vent on the Northeast Rift Zone ceased on December 10 and sulfur dioxide emissions have decreased to near pre-eruption background levels. Volcanic tremor and earthquakes associated with the eruption are greatly diminished.”

© Jan TenBruggencate 2022

Mauna Loa quiet, but maybe not done erupting

 

Things are confusing atop Mauna Loa.

There is no longer any fresh lava erupting anywhere on the surface of the mountain, either at the summit where the eruption started, or on the Northeast Rift Zone, which produced the flow that threatened the Saddle Road.

The major source of lava flows, Fissure 3, is no longer producing molten rock.

The entire surface area where new lava erupted since the eruption began November 27 is cooling down.

The measurable tremor under the summit, which indicates magma is moving underground, appears to have stopped.

Sulfur dioxide gas production is way down.

That would all suggest that the eruption is over.

But USGS’s Hawaiian Volcano Observatory is cautious.

“The Northeast Rift Zone eruption of Mauna Loa may still be active,” it said in its Sunday (December 11, 2022) update.

One data point: The summit is once again inflating.

“The significance of the continuing inflation while the flow field is inactive is not yet clear,” the scientists said.

In past eruptions, once a shutdown like this has occurred, Mauna Loa hasn’t been seen to return to big time eruption, but it might, or it might return to something less than that. Or it might be done.

As we’ve been doing, we wait.

© Jan TenBruggencate 2022

Mauna Loa is like "Jaws." Something's moving below the surface. When will it rise?

 

(Image: Webcam shot at Mauna Loa's Fissue 3, taken this morning, December 10, 2022. Credit: USGS.)

The Mauna Loa eruption right now is a little like the movie Jaws: something's moving under the calm surface...when will it rise?

The eruption that started November 27 has stopped producing much lava. Its threat to the Saddle Road is, for now, abated. It's not fountaining any more. There's just a pond of lava at the Fissure 3 vent, which is spilling over into short, stagnating flows. Significantly less gas is being pumped out of the fissure.

But deep below, magma is still moving up into the upper reaches of the mountain. 

"Tremor (a signal associated with subsurface fluid movement) continues beneath the currently active fissue," the USGS reported this morning,

"This indicates that magma is still being supplied to the fissure and activity is likely to continue as long as we see this signal."

Yesterday, the USGS suggested the fountaining could return any time, Today, the scientists downplayed that possibility: "None of the eight recorded eruptions from Mauna Loa's Northeast Rift Zone returned to high eruption rates after those rates decreased significantly." 

So the magma is still rising underground, but it's not erupting. 

Hmm. Can you hear the "Jaws" drumbeat?

© Jan TenBruggencate 2022

Quiet on the Mountain: Mauna Loa in a pause? Not quite.

Things are pretty calm up on Mauna Loa, with the active fissure glowing, but not aggressively fountaining, and still apparently producing a little lava.

It will be some time before it is clear what's going on, whether this is the start of a pause in the Mauna Loa eruption, or the end of this event, or something entirely different.

"A return to high levels of lava discharge could occur," the USGS said in its Friday morning update.

The image above is a USGS webcam view of Fissure 3, which until two days ago was pumping with high lava fountains and feeding a long flow that threatened the Saddle Road/Daniel K. Inouye Highway. The image was collected at 8:36 a.m. Friday, December 22, 2022.

There's still some glowing rock, but fountains are not visible in this image. The USGS update late Thursday indicated that the amount of lava had dropped significantly from Wednesday to Thursday. And this morning it reported that there was low fountaining that was feeding a small flow that goes a mile or so from the vent.

The long flow that got to within 1.7 miles of the highway is essentially stopped, although as it cools, it is spreading out a little.

An image from a webcam a few minutes later overlooking Moku'aweoweo  indicated the summit caldera was similarly quiet.

Another webcam shot from Mauna Kea, looking across to Mauna Loa at 8:36 a.m. shows smoke up on the Mauna Loa rift zone, but no fire.

View the webcam images yourself here.

What does it all mean? The Hawaiian Volcano Observatory scientists admit they're not certain.

"The significance of the reduced supply of lava is not yet clear; it is common for eruptions to wax and wane or pause completely," the USGS reported in its morning update.

It reported that there is still magma moving up into the mountain, as indicated by continuing tremor within Mauna Loa.

© Jan TenBruggencate 2022

Mauna Loa eruption scaling back

The Saddle Road appears safe for now from being engulfed in lava.

Mauna Loa dramatically reduced its eruption lava volume overnight from December 7 to 8, and is no longer feeding the long flow that had threatened the Daniel K. Inouye Highway. The flow front is stalled and cooling about 1.7 miles from the highway. 

The USGS reported: "Lava is overtopping channels near the vent with flows extending no farther than 2.5 mi (4 km) from the vent. The channels below this point appear drained of lava and probably no longer feed the main flow front."

That said, tremor measuring the flow of magma under the volcano indicates there's still molten rock being fed to the mountain.

So what happens next? We'll see.

See the full USGS report here.

© Jan TenBruggencate 2022

Is the Saddle Road toast?

 The Saddle Road is toast.

A photo from earlier in the eruption, from an overflight the morning of November 30, 2022.  USGS image by K. Mulliken. 

I don’t hear a lot of folks talking about it, but the way the Mauna Loa eruption is going, the cross-island Daniel K. Inouye Highway within days will be impassable going east and west.

That has huge implications for passenger and supply transport between the Hilo side of Hawai’i Island to the east, and the Waimea and Kona side to the west. But it also has import for high-elevation science.

The main lava flow has already cut off access to the critical scientific center, Mauna Loa Observatory, and on its current course, it also has the potential to shut down access to the massive astronomy facilities at Mauna Kea. 

Judging from the topography, the east-west access will be gone before Mauna Kea access is threatened.

Mauna Loa may do what the Mauna Kea protests could not.

Mauna Loa’s eruption is currently focused on the northeast flank. A feature called Fissure 3 is feeding a long lava flow headed northward into the saddle between Mauna Kea and Mauna Loa.

It is in familiar territory for Madame Pele, with a 1935 flow on its right flank and an 1843 flow on its left. Both of those flows crossed the current route of the Daniel K. Inouye Highway.

The 1935 flow pooled in the saddle for a few days, then turned east and headed downslope for Hilo. The Air Force in late December 1935 bombed that flow to try to protect Hilo. Ultimately, that eruption stopped before Hilo could be impacted. Here is a National Park Service story on that.  

It lasted from November 21, 1935 to January 2, 1936. Eight weeks. 

The 1843 flow lasted three months.

This eruption started November 27, 2022, and shows no signs of stopping. The lava is now on pretty flat ground, less than two miles from the highway, and creeping forward at give-or-take 1,000 feet per day. But that could change.

The Hawaiian Volcano Observatory reports: “Lava flow advance rates may be highly variable over the coming days and week. Lava flows advance more slowly, spread out, and inflate on the flat ground between Mauna Loa and Mauna Kea. Individual lobes may advance quickly, and then stall. Additional breakouts may occur if lava channels get blocked upslope. There are many variables at play, and the direction and timing of flow advances are expected to change over hours to days, making it difficult to estimate when or if the flow will impact Daniel K. Inouye Highway.”

Realistically, things that can save the highway from being overflowed are an early stop of the eruption, or the activation of an entirely new fissure that allows the current flow to cool and harden in place.

© Jan TenBruggencate 2022

Volcanic pyrotechnics: Mauna Loa is back

 

It’s been a while since the night sky over the highest parts of Hawai’i Island were lit bright orange by something other than the sun.

(The image above, an aerial USGS photo taken early Dec. 6 by L. Gallant, displays fountains at Mauna Loa Fissue 3. The fountains are running at 40 meters on average, with bursts to 100 meters.)

The new eruption of Mauna Loa is filling those skies—and the internet—with stunning shots of blazing fountains, glowing clouds and sinewy Halloween-colored lava flows.

Mauna Loa took a pause after its two-volcano show with Kīlauea in 1984. It was a long pause by Mauna Loa standards. The big volcano—the biggest one in the world—has erupted every five years or so since the early 1800s, and once every 6 years over the last few millennia. So a 38-year quiet is quite something.

There used to be arguments among volcano folks about whether the underground plumbing made it even possible for Mauna Loa and Kīlauea to erupt at the same time. They did in 1984, and again now, so that’s settled. They generally do not erupt together, but they can.

The new mystery is whether it’s possible for Mauna Loa, Kīlauea AND the younger volcano Kama’ehuakanaloa to erupt at once. As far as we know, that has not yet happened.

Kama’ehuakanaloa, formerly known as Lō’ihi, lies in the waters 20+ miles east of Nā’alehu. It is not currently erupting, although occasional swarms of earthquakes show that there’s magma moving under that seamount. We’ll see.

And might it be possible for concurrent eruptions of those three plus Hualalālai, which last erupted in 1801, and isn’t done yet. Mauna Kea and Haleakalā eruptions are also possibilities, but all three seem to be geologically napping at this time.

Mauna Loa’s eruptive phases tend to be big shows, but short ones. They range from a few days or weeks to as much as a year. That’s short compared to Kīlauea’s, which can go on for decades, but which produce far less lava.

Mauna Loa’s flows can run to the sea very quickly down sloping ground, depending on the direction they take. During the past two centuries they have reached the shoreline in North Kona, South Kona and Ka’ū, and made it to the outskirts of Hilo. Mauna Loa flows have reached from the eruption site to the coast, tens of miles away, in as little as a few hours.

That’s not happening right now, largely because the 2022 eruption is currently flowing into the flattish lands of the saddle between Mauna Loa and Mauna Kea, but if the eruption continues, and the lava spills out into steeper slopes, it could get moving pretty quickly.

As this is written, the hot lava is less than two miles from the old Saddle Road, now the Daniel K. Inouye Highway. If that cross-island artery is cut, disruptions for residents will be significant.

Mauna Loa’s lava production has been estimated at an estimated 100 cubic meters per second. (By my calculations, that would fill an average Hawai’i house every couple of seconds, an average apartment building every couple of minutes.)

 If you’re interested in this eruption, the National Park Service has an information site here, and it includes lots of links to other sources of information. 

© Jan TenBruggencate 2022

Blazing sunsets, redux

Raikoke Volcano in the Kuril Islands
in the northwest Pacific, taken June 22, 2019.
Credit: NASA.

Those spectacular Hawaiian sunset photos that have been showing up recently on Facebook, Twitter and Instagram are likely the result of volcanic emissions being dumped into the upper atmosphere during the summer.

But volcanic activity hasnʻt stopped. Just in the past week, in addition to ongoing volcanic eruptions, there have been four new ones. The volcanic haze that gets ejected into the atmosphere can color sunrises and sunsets in blazing oranges and purples.

The recent eruptions include these:

Kikai at Japanʻs Satsuma Iwo-jima, which is a small eruption probably not contributing a lot to sunsets. The dust plume was estimated at a kilometer high.

Klyuchevskoy in Russiaʻs Central Kamchatka, which has a dust and steam plume blowing 130 kilometers downwind.

The volcano at Metis Shoal, Tonga, erupted Nov. 1 and created a new island, but it appears to have stopped.

And Shishaldin in the Fox Islands of Alaska is reported still an active eruption, but without reports of a lot of dust and steam.

So those volcanoes that erupted most recently are comparatively small have not created a lot of the color weʻre seeing in the early evening. Most of the impact of recent sunsets comes from Ulawun volcano in Papua New Guinea, which erupted June 26, 2019, and Raikoke in the Kuril Islands, which erupted June 22, 2019.

Ulawun sent up a plume 20 kilometers or more high. Raikoke went 13 to 17 or more kilometers high. At those elevations, the dust and gas got into upper level winds and were transported around the globe.

"The dominant aerosol layer is actually formed by sulfur dioxide gas which is converted to droplets of sulfuric acid in the stratosphere over the course of a week to several months after the eruption. 

Winds in the stratosphere spread the aerosols until they practically cover the globe. Once formed, these aerosols stay in the stratosphere for about two years," said a NASA article.  

If you want to keep track for yourself, hereʻs a website that monitors recent eruptions. It is produced jointly by the Smithsonian Institution Global Volcanism Program and the U.S. Geological Survey.  

For some reason, there has been an upsurge in sunset picture taking. Perhaps itʻs associated with clearer weather. But the underlying causes havenʻt changed much since RaisingIslandsʻ last report on the 2019 sunsets here. 

© Jan TenBruggencate 2019

Those blazing new internet sunsets? Thank a couple of summer volcanic eruptions.

Great sunsets are the new kitties on social media.

Lots of folks are posting their photographs of 

spectacular glowing orange and purple sunsets. Whereʻd they come from? 

Once again, this pulse of superb sunsets is thanks to atmospheric pollution from a volcano.

(Since youʻll find sunset shots elsewhere, hereʻs a shot of whatʻs causing them. This is the plume from Kuril Islands volcano Raikoke, taken from the International Space Station. Credit: NASA.)

This time, it is the Russian volcano, Raikoke, which erupted in June this year. The volcano dumped vast amounts of sulfur gas into the upper atmosphere, giving sunsets a new reddish-purple tinge.

High altitude balloon measurements just found sulfur density 20 times normal in the stratosphere. The story was reported in last weekʻs issue of the journal Science. 

There were some great sunsets in 2008, that time due to the ash-filled eruption of the Alaskan volcano Kasatochi. It exploded in August of that year.  

And there were years of great sunsets in the 1990s from the Philippine volcano Pinatubo, which erupted in June 1991.

(In the NASA images from space at left, the upper shot is before Pinatubo. In the lower image, the layers of aerosols from 1991ʻs eruption of Pinatubo are visible in the atmosphere.)

The latest bit of atmospheric pyrotechnics is thanks to Raikoke or Raykoke, a Russian volcano that dominates an island in the Kuril chain of the Northwest Pacific. The June 22 eruption ejected a plume of sulfur dioxide and particulate matter 50,000 feet into the atmosphere.

The Raikoke event may be helped a little by another eruption in the first week of August, this one from the volcano Ulawun in Papua New Guinea. Its plume is believed to have reached 63,000 feet.

But while those are impressive events, the volume is not believed to be sufficient to alter climate. Pinatubo was identified responsible for a two-year period of global cooling that temporarily halted the planetʻs pattern of warming.

Pinatubo lifted 15 million tons of sulfur dioxide into the atmosphere, where it formed a layer of sulfuric acid droplets that both blocked sunlight and made great sunsets. 

© Jan TenBruggencate 2019

Pele slipping upslope to Mauna Loa, pumping magma, USGS raises caution level yellow

Peleʻs Kilauea home Halema`uma`u. Credit: USGS

Is Madame Pele shifting residences, slipping upslope from her Kīlauea playground to her mountain palace at Mauna Loa?

It seems that way because thatʻs where sheʻs rumbling now.

After last yearʻs dramatic destruction on Kīlaueaʻs East Rift Zone, destroying homes by the hundreds and forests by the thousands of acres, Kīlauea has been quiet. That quietness, according to the USGS Volcano Hazards Program, has now continued for some months.

What of the other Hawaiian active volcanoes?

Haleakala remains quiet, as well. Hualalai too. Mauna Kea, which hasnʻt erupted in 4,600 years, shudders now and then, but mainly remains serenely calm. Lo`ihi, the undersea volcano building off the Hawai`i Island coast, shakes occasionally, but doesnʻt appear ready to erupt.

But seismic observations indicate thereʻs new activity now under massive Mauna Loa—the biggest active volcano on the planet. Not that itʻs ready to release raw lava in the short term. But right now, it is the most active of the Hawaiian volcanoes.

Magma—the term for molten rock underground—is moving. The volcano stores magma in different places, and one of them is a fairly shallow reservoir beneath the summit. Earthquake activity around that reservoir indicates that thereʻs movement in that region.

The Hawaiian Volcano Observatory uses a range of equipment to take, as it were, Peleʻs pulse. There are seismic monitors, and tilt meters, and even satellite measurements. You can see the observatoryʻs reporting on Mauna Loa here.

So far, the geologists are using very careful language, clearly intending to inform but not alarm.

"For the past several months, earthquake and ground deformation rates at Mauna Loa Volcano have exceeded long term background levels. An eruption is not imminent and current rates are not cause for alarm. However, they do indicate changes in the shallow magma storage system at Mauna Loa," the observatory reports.

It has upped Mauna Loaʻs alert level from placid green to cautious yellow. That means thereʻs stuff going on but the experts donʻt think an eruption is imminent. For perspective, the next two levels would be orange (eruption possible in as little as two weeks) and red (eruption likely within 24 hours.)

Weʻre nowhere near those more fiery color levels, but again, thereʻs something going on. It started with a significant earthquake "swarm" in October 2018. Since then, quake level and the actual swelling and shrinking of the mountain have been above background levels.

Theyʻre not yet a big deal, but this is the kind of activity that has led to eruptions in the past.

"Seismic stations have recorded an average of at least 50 shallow, small-magnitude earthquakes per week beneath Mauna Loa's summit, upper Southwest Rift Zone, and upper west flank. This compares to a rate of fewer than 20 per week in the first half of 2018. 

Shallow earthquakes are occurring in locations similar to those that preceded Mauna Loa's most recent eruptions in 1975 and 1984," the observatory wrote.

The near-surface magma storage area seems to be inflating, filling with molten rock, they say. That said, the volcano has had similar activity twice since 2000, without an eruption...so this is not a countdown.

"As has happened before, it is possible that current low-level unrest will continue and vary in intensity for many months, or even years without an eruption. It is also possible that the current unrest is an early precursor to an eventual eruption. At this time, we cannot determine which of these possibilities is more likely," the observatory reported.

If an eruption nears, there should be plenty of warning signs: "These signs could include further increases in rates of earthquakes and ground deformation, increases in the sizes of earthquakes, an increase in surface temperatures, or an increase in visible steam plumes or sulfur dioxide emissions."

Mauna Loa erupted 33 times since 1843. That works out to once every five years, although some of those were quite small. Among larger eruptions—ones whose lava covered 10 square kilometers or more, there were 16—one every 11 years.

The last eruption was in 1984, meaning itʻs been 35 years without a Mauna Loa eruption.

Kīlauea was erupting during much of Mauna Loaʻs recent quiet period. For many years, some scientists argued that a connection between the volcanoes prevented one from erupting while another was spewing lava. You can still see this information on websites, but the 1984 double eruption proved this wrong. Hereʻs a New York Times storyon that. 

© Jan TenBruggencate 2019

Kīlauea's 2018 eruption--what happened, and how soon can it come again?

The 2018 Kīlauea eruption is less of a news story months after it stopped, but what the heck happened there, and can it happen again soon?

"The 2018 eruption of Kīlauea Volcano in Hawai‘i included both a summit caldera collapse and a flank fissure eruption, a complex event observed only a handful of times in modern history," wrote a team of more than 50 premier volcano experts in the January 25 issue of the journal Science.

And the short answer to the second question above is no, it probably can not happen again for many more years. More on that later.

Because Kīlauea is so well instrumented and staffed by geologists, the study of its eruption last year is providing details of how such eruptions work, and it will also provide important information on how to mitigate risk in future eruptions here and around the world, they said.

In March and April 2018, the summit and slopes of Kīlauea were inflating, indicating increasing underground pressure from magma buildup. There were changes at the summit and at the Pu`u `Ō`ō vent on the East Rift Zone.

On April 30, the Pu`u `Ō`ō crater collapsed, and scientists were tracking quakes as they began moving 20 kilometers downrift toward the residential area of Leilani Estates.

On May 3, the ground opened up there, and lava began erupting among house sites.

The island shook on May 4 with the biggest quake in 43 years—magnitude 6.9.

Over the next several months, the community was ravaged by absolutely immense quantities of lava—many times the amount that had been erupting daily from Pu`u `Ō`ō.

Fast-flowing rivers of molten rock ripped through homes, across roads, through gardens. Dense clouds of gas choked refugees and emergency workers, and acid burned the leaves of agricultural crops. Coastal parks and landmarks were destroyed. There were volcanic ash explosions at the summit. And much more.

Geologists determined that much of the lava came from magma stored in a chamber a mile or so deep, below the eastern side of Halema`uma`u Crater. It is one of two magma storage chambers under Kilauea, the other being deeper and off to the west.

We will number the four main things geologists figure were at play in how big and fast this went.

Both because (1) the pre-eruption pressure was so high, and because (2) the elevation of the Leilani Estates area vents was so low, geologists said, the volume of lava erupted was enormous—far more in a shorter time than ever before documented on this volcano.

The draining under the summit caused the ground above it to collapse, causing severe damage to roads and buildings at the summit. The famed Jaggar Museum was closed, and may never reopen due to structural concerns. The collapse of the summit (3) may also have created more underground pressure and shipped more magma to Leilani Estates.

That big May 4 earthquake (4) may also have opened up some space for the eruption to proceed at high volume.

Previous eruptions had gone on for years. Could this eruption, at these enormous levels of lava production, continue for very long? Even during the eruption, the experts were saying this could not continue forever, and sure enough, after just a few months, it ended.

"The strong hydraulic connection between the summit and (lower east rift zone), once established, remained until the summit magmatic system drained to a point at which the (lower east rift zone) eruption could no longer be sustained."

And could an eruption like this one come back anytime soon?

Probably not, the authors of the Science paper said.

"It may take several years before enough magma can accumulate beneath the summit to erupt," the Science paper said. As additional evidence, the authors noted that after a summit collapse in 1924, aside from some small eruptions at Halema`uma`u, there were no Kīlauea eruptions for 18 years.

The Hawaiian Volcano Observatory worked closely with county and state emergency management officials, and were able to provide robust and, importantly, early notification to the community about the eruption.

And this eruption provided so much data that it's likely future eruptions will be forecast even more accurately, the authors said.

The research collected during the 2018 eruption "yielded new insights into poorly known processes such as caldera collapse, small-scale explosive basaltic volcanism, vigorous lava effusion and degassing, and magma transport and flank stability at shield volcanoes," the science paper said.

"Continued exploitation of these rich datasets will undoubtedly yield additional discoveries that will refine understanding of Kīlauea Volcano and volcanic processes and hazards in general.

© Jan TenBruggencate 2019

Kīlauea: Dramatic, long-term changes continue. Catastrophic event possible but unlikely.

It is tough to grasp the enormous changes going on at Kīlauea volcano, including the impact on the prized national park as well as the catastrophic impacts on downslope residents.

(The view at right is from Volcano House. If you've looked over Kīlauea from this site, you'll recognize how completely different it looks now. The image is from an automated National Park Service camera.)

In the day-to-day news cycle, we tend to use a tight focus on what has been destroyed lately--the hundreds upon hundreds of lost homes, the thousands of acres of forest gone, the loss of transportation systems and the destruction of the Jaggar Museum--but scientists at the Hawaiian Volcano Observatory recently took a wider look, and the future doesn't look bright.

The U.S. Geological Survey report is entitled Volcanic Hazard at the Summit of Kīlauea, June 29, 2018 Update.

The Kīlauea caldera is collapsing at two to three inches daily, dramatically changing the look of the landscape. The lava lake has dropped 1,000 feet from its high. The parking lot at Halema`uma`u has been torn up like a sheet of paper, and it is covered by ash and rocks that have been ejected from the firepit.

If you remember the Halema`uma`u overlook, remember it well. It has now been closed since 2008, and if you ever see it again, it will look very different. The crater, for example, is four times as big as it was.

For the next few months, we can anticipate more earthquakes, ground cracking, ash plumes, vog and large scale deformation as Halema`uma`u engulfs more and more of Kīlauea Crater. It may eventually take up all of what we now know as the crater.

A sudden, massive, severely damaging collapse is considered possible, although unlikely. New lava fountains hundreds of feet high are possible. So is an earthquake much bigger than the ones felt recently.

"Strong earthquakes can occur at any time, and the risk of these events is larger now due to ongoing stress changes in and around the caldera. These earthquakes will not necessarily occur during swarm seismicity or in association with (collapse-explosion) events, may be large, and may happen outside of the caldera," the report says.

The only good news in this scenario is that if a massive, destructive collapse of the caldera occurs, there ought to be some notice of it:

"…Large-scale hazardous caldera collapse is a possible future outcome, although it is considered to be very unlikely and should be preceded by detectable warning signals. HVO should recognize these warning signs by direct observation and instrumental monitoring and, should they be detected, will alert authorities and the public."

That said:.

"The most likely course of activity for the immediate future at the summit of Kīlauea Volcano is continued subsidence of the caldera floor, episodic slumping into Halema`uma`u, felt moderate-sized earthquakes, and small ash plumes. The duration of this activity may be related to the duration of the (Lower East Rift Zone) eruption but cannot be confidently predicted," the USGS says.

In short, the most likely scenario is that we keep seeing what we’ve been seeing for the past couple of months. The less likely scenario is that it gets worse.

You can keep track of the technical details of the eruption at the USGS Hawaiian Volcano Observatory website. 

Another great resource is the lyrical narratives of retired Hawai`i Volcanoes National Park ranger Bobby Camara, Dispatches from Volcano. 

© Jan TenBruggencate 2018

Hawai`i data shows CO2 at record levels in atmosphere: and growing faster than ever

Annual CO2 growth rate. Source: NOAA, Scripps

Carbon dioxide levels in the atmosphere continue to grow at a record rate, promising that climate change will continue long beyond our lifetimes.

That's from data collected in Hawai`i—at the Mauna Loa Observatory, which has been collecting atmospheric CO2 data for 60 years. 

The Scripps release on the milestone is here.

In May, those levels reached a record high of 411.31 parts per million.

The latest tally was released last week by scientists from Scripps Institution of Oceanography at the University of California San Diego and NOAA.

And despite international efforts to control emissions, they appear to not be effectively under control. The level of emissions is not only continuing to grow, but it's growing faster. It was growing at 1.5-1.6 parts per million in the 1980s through 1990s, but during the past 10 years has been growing at 2.2 parts per million.

“Many of us had hoped to see the rise of CO2 slowing by now, but sadly that isn't the case. It could still happen in the next decade or so if renewables replace enough fossil fuels,” said Scripps CO2 program director Ralph Keeling, whose father Charles Keeling started the Mauna Loa CO2 program in 1958.

But while it's possible to reverse the growth trend in CO2, for species of all kinds, including humans, the future isn’t bright.

“Today's emissions will still be trapping heat in the atmosphere thousands of years from now.” Pieter Tans, lead scientist of NOAA’s Global Greenhouse Gas Reference Network.

With Kilauea volcano erupting continually for so long, many ask if that has a significant impact on atmospheric carbon dioxide. Researchers say it's clear that most of the CO2 change is from fossil fuel use, not the volcano.

And the proximity of Kilauea to Mauna Loa is also not a big factor. The high rate of growth in atmospheric CO2 is not only being observed at Mauna Loa but also at other sites in NOAA’s Global Greenhouse Gas Reference Network.

© Jan TenBruggencate 2018

Kalalau ridge see-through hole got bigger this summer

Keanapuka feature at center bottom.
Credit: Photo by Jan TenBruggencate

A ridge on Kalalau Valley’s northeast wall has long had a hole punched right through it, but the hole is now much bigger and more visible than it once was--thanks to a series of landslides this summer

.

That’s the conclusion from numerous Kalalau veterans about a feature known as Keanapuka. It is identified by that name on old maps.

The name Keanapuka itself—meaning cave with a hole—suggests the existence of the feature. But a series of rock slides earlier this year—likely late this summer—expanded its size.

Steve Perlman, a researcher with the state Plant Extinction Prevention Program, has spent many hours rappelling down the Kalalau cliffs, locating and preserving native plant species. He and longtime botanical partner Ken Wood arguably know the Kalalau cliff faces better than anyone alive.

And he knows Keanapuka well.

“There was always a smaller puka there on that ridge. But a few months ago, about 3, there were major rock slides with a much larger hole now,” Perlman said in an email.

Others, responding on Facebook, confirmed that they were aware of the long-existing smaller hole.

Kimberlee Stuart thought the size had changed: “Saw this last spring- not sure if it was that big though.”

Paul Clark, who has operated by boat along Na Pali Coast, said it has been visible from the sea: “Have seen this by boat and pointed it out since 1995 - (sure it was there before then too).”

And Wayne Jacintho, a longtime hiker in Kaua`i’s uplands, said that the hole can sometimes in the late afternoon be a lens through which the sun shines from the west, creating a window of light on the valley wall next door to the east.

“It's an old hole. If you're down the ridge on the left (southwest) side of Kalalau Valley, at the correct time of the year, in the afternoon, (looking northeast) you'll see the sun shine thru the hole and illuminate the wall to the right in the ravine,” Jacintho wrote. (I slightly edited his post for clarity.)

Keanapuka place name on the Kauai Recreaation Map of the
Na Ala Hele Hawai`i Trail & Access System. 

The site is noted on the Western Kauai Recreation Map of the Na Ala Hele Hawai`i Trail and Access System.

Keanapuka is not easily visible from anywhere accessible by road. The best view is late afternoon from the Pihea Trail along the back (southeast) end of Kalalau Valley. The trail starts at Pu`u O Kila, a promontory and lookout at the end of the Koke`e Road.

As we noted in a previous post, there are many examples of such voids or arches in the volcanic ridges of the Islands, where a narrow middle section of a rock feature breaks away, but leaves the rock arch overhead.

© Jan TenBruggencate 2017