A year on, we know why the Tongan eruption was so violent. It’s a wake-up call to watch other submarine volcanoes

 

Sung-Hyun Park/Korea Polar Research Institute

The Kingdom of Tonga exploded into global news on January 15 last year with one of the most spectacular and violent volcanic eruptions ever seen.

Remarkably, it was caused by a volcano that lies under hundreds of metres of seawater. The event shocked the public and volcano scientists alike.

Was this a new type of eruption we’ve never seen before? Was it a wake-up call to pay more attention to threats from submarine volcanoes around the world?

The answer is yes to both questions.

The Hunga Tonga-Hunga Ha'apai volcano was a little-known seamount along a chain of 20 similar volcanoes that make up the Tongan part of the Pacific “Ring of Fire”.

We know a lot about surface volcanoes along this ring, including Mount St Helens in the US, Mount Fuji in Japan and Gunung Merapi of Indonesia. But we know very little about the hundreds of submarine volcanoes around it.

Scientists have good understanding of land-based volcanoes along the Pacific Ring of Fire, but far less so about seamounts. Getty Images

It is difficult, expensive and time-consuming to study submarine volcanoes, but out of sight is no longer out of mind.

Tongan eruption breaks records

The Hunga Tonga-Hunga Ha'apai eruption has firmly established itself in the record books with the highest ash plume ever measured and a 58km aerosol cloud “overshoot” that touched space beyond the mesosphere. It also triggered the largest number of lightning bolts recorded for any type of natural event.

The injection of large amounts of water vapour into the outer atmosphere, along with “sonic booms” (atmospheric pressure waves) and tsunami that travelled the entire world, set new benchmarks for volcanic phenomena.

COVID hampered access to Tonga during the eruption and its aftermath, but local scientists and an international scientific collaborative effort helped us discover what drove its extreme violence.

Eruption creates a giant hole

A team from the Tongan Geological Services and the University of Auckland used a multi-beam sonar mapping system to precisely measure the shape of the volcano, just three months after the January blast.

We were astonished to find the rim of the vast submarine volcano was intact, but the formerly 6km diameter flat top of the submarine cone was rent by a hole 4km wide and almost 1km deep.

The Hunga Tonga-Hunga Ha'apai crater and caldera before and after the eruption. Sung-Hyun Park/Korea Polar Research Institute, CC BY-SA

This is known as a “caldera” and happens when the central part of the volcano collapses in on itself after magma is rapidly “pumped out”. We calculate over 7.1 cubic kilometres of magma was ejected. It is almost impossible to envisage, but if we wanted to refill the caldera, it would take one billion truck loads.

It is hard to explain the physics of the Hunga eruption, even with the large magma volume and its interaction with seawater. We need other driving forces to explain especially the climactic first hour of the eruption.

Mixed magmas lead to chain reaction

Only when we examined the texture and chemistry of the erupted particles (volcanic ash) did we see clues about the event’s violence. Different magmas were intimately mixed and mingled before the eruption, with contrasts visible at a micron to centimetre scale.

Isotopic “fingerprinting” using lead, neodymium, uranium and strontium shows at least three different magma sources were involved. Radium isotope analysis shows two magma bodies were older and resident in the middle of the Earth’s crust, before being joined by a new, younger one shortly before the eruption.

The mingling of magmas caused a strong reaction, driving water and other so-called “volatile elements” out of solution and into gas. This creates bubbles and an expanding magma foam, pushing the magma out vigorously at the onset of eruption.

This intermediate or “andesite” composition has low viscosity. It means magma can be rapidly forced out through narrow cracks in the rock. Hence, there was an extremely rapid tapping of magma from 5-10km below the volcano, leading to sudden step-wise collapses of the caldera.

The caldera collapse led to a chain reaction because seawater suddenly drained through cracks and faults and encountered magma rising from depth in the volcano. The resulting high-pressure direct contact of water with magma at more than 1150℃ caused two high-intensity explosions around 30 and 45 minutes into the eruption. Each explosion further decompressed the magma below, continuing the chain reaction by amplifying bubble growth and magma rise.

After about an hour, the central eruption plume lost energy and the eruption moved to a lower-elevation ejection of particles in a concentric curtain-like pattern around the volcano.

This less focused phase of eruption led to widespread pyroclastic flows – hot and fast-flowing clouds of gas, ash and fragments of rock – that collapsed into the ocean and caused submarine density currents. These damaged vast lengths of the international and domestic data cables, cutting Tonga off from the rest of the world.

This map shows the sites of ongoing venting after the eruption. Marta Ribo/AUT, CC BY-ND

Unanswered questions and challenges

Even after long analysis of a growing body of eyewitness accounts, there are still major unanswered questions about this eruption.

The most important is what led to the largest local tsunami – an 18-20m-high wave that struck most of the central Tongan islands around an hour into the eruption. Earlier tsunami are well linked to the two large explosions at around 30 and 45 minutes into the eruption. Currently, the best candidate for the largest tsunami is the collapse of the caldera itself, which caused seawater to rush back into the new cavity.

This event has parallels only to the great 1883 eruption of Krakatoa in Indonesia and has changed our perspective of the potential hazards from shallow submarine volcanoes. Work has begun on improving volcanic monitoring in Tonga using onshore and offshore seismic sensors along with infrasound sensors and a range of satellite observation tools.

All of these monitoring methods are expensive and difficult compared to land-based volcanoes. Despite the enormous expense of submarine research vessels, intensive efforts are underway to identify other volcanoes around the world that pose Hunga-like threats.

Shane Cronin, Professor of Earth Sciences, University of Auckland

This article is republished from The Conversation under a Creative Commons license.

How Edgar Allan Poe became the darling of the maligned and misunderstood

 

Could the pugnacious writer ever have imagined that he would one day become a cult hero? Nick Lehr/The Conversation via DALL-E 2, CC BY-SA

Edgar Allan Poe, who would have turned 214 years old on Jan. 19, 2023, remains one of the world’s most recognizable and popular literary figures.

His face – with its sunken eyes, enormous forehead and disheveled black hair – adorns tote bags, coffee mugs, T-shirts and lunch boxes. He appears as a meme, either sporting a popped collar and aviator shades as Edgar Allan Bro, or riffing on “Bohemian Rhapsody” by muttering, “I’m just Poe boy, nobody loves me” as a raven on his shoulder adds, “He’s just a Poe boy from a Poe family.”

Netflix has sought to capitalize on the writer’s popularity, recently releasing the mystery-thriller “The Pale Blue Eye,” which features Poe as a West Point cadet, where he spent less than a year before being court-martialed. Netflix also has a Poe-inspired miniseries, “The Fall of the House of Usher,” set to be released sometime in 2023.

But as a Poe scholar, I sometimes wonder whether Poe’s appeal is less about the power and complexity of his prose and more about an attraction to the idea of Poe.

After all, Poe’s most famous literary creations tend to be unsympathetic villains. There are psychopaths who perpetuate seemingly motiveless murders in “The Black Cat” and “The Tell-Tale Heart”; protagonists who abuse women in “Ligeia” and “The Fall of the House of Usher”; and characters who exact cruel, fatal revenge on unwitting victims in “The Cask of Amontillado” and “Hop-Frog.”

The degenerate characters whose perspectives Poe invites readers to inhabit don’t exactly align with a cultural moment characterized by the #MeToo movement, safe spaces and trigger warnings.

At the same time, the conception of Poe the writer seems to tap into a cultural affection for outsiders, nonconformists and underdogs who ultimately prove their worth.

A character assassination that misfires

The idea of Poe the underdog began with his death in 1849, which was greeted by a cruel notice in the New York Tribune: “This announcement will startle many, but few will be grieved by it.”

The obituary writer, who turned out to be Poe’s sometime friend and constant rival Rufus W. Griswold, claimed that the deceased had “few or no friends” and proceeded with a general character assassination built on exaggerations and half-truths.

Strange as it seems, Griswold was also Poe’s literary executor, and he expanded the obituary into a biographical essay that accompanied Poe’s collected works. If this was a marketing ploy, it worked. The friends that Griswold claimed Poe lacked rose to his defense, and journalists spent decades debating who the man really was.

Rufus W. Griswold penned the first draft of Poe’s life and legacy. raveler1116/DigitalVision Vectors via Getty Images

During Poe’s lifetime, most readers encountered his work through magazines, and he was rarely well paid. But Griswold’s edition went through 19 printings in the 15 years after Poe’s death, and his stories and poems have been endlessly reprinted and translated ever since.

Griswold’s defamatory portrait, along with the grim subject matter of Poe’s stories and poems, still influences the way readers perceive him. But it has also produced a sustained reaction or counterimage of Poe as a tragic hero, a tortured, misunderstood artist who was too good – or, at any rate, too cool – for his world.

While translating Poe’s works into French in the 1850s and 1860s, the French poet Charles Baudelaire promoted his hero as a kind of countercultural visionary, out of step with a moralistic, materialistic America. Baudelaire’s Poe valued beauty over truth in his poetry and, in his fiction, saw through the self-improvement pieties that were popular at the time to reveal “the natural wickedness of man.” Poe struck a chord with European writers, and as his international stature rose in the late 19th century, literary critics in the U.S. wrung their hands over his lack of appreciation “at home.”

Poe’s underdog story takes off

By the turn of the 20th century, the stage was set for Poe to be embraced as the perennial underdog. And Poe often did appear on stage around this time, as the subject of several biographical melodramas that depicted him as a tragic figure whose lack of success had more to do with a hostile cultural and publishing environment than his own failings.

That image appeared on the silver screen as early as 1909 in D.W. Griffith’s short film “Edgar Allen Poe.” With Poe’s wife, Virginia, languishing on a sick bed, the poet ventures out to sell “The Raven.” After meeting rejection and scorn, he manages to sell his manuscript and returns home with provisions for his ailing wife, only to find that she has died.

Later films also depict Poe as being misunderstood or underappreciated in his lifetime. A wildly inaccurate biopic, “The Loves of Edgar Allan Poe,” released in 1942, ends with a voice-over commenting, “…little did [the public] know that the manuscript of ‘The Raven,’ which he tried in vain to sell for $25, would years later bring the price of $17,000 from a collector.”

In ‘The Loves of Edgar Allan Poe,’ Poe’s talents are overlooked, as ‘men scoffed at his greatness.’ LMPC/Getty Images

In real life, while an early draft of “The Raven” was declined by one editor, Poe had no trouble selling the poem, and it was an immediate sensation.

But here “The Raven” becomes a stand-in for Poe himself, something dark and mysterious that, according to legend, people in Poe’s time failed to appreciate.

Poe is an obscure writer and amateur detective in the 1951 film “The Man with a Cloak,” which ends with a saloonkeeper allowing the rain to wash away the ink on an IOU that Poe gave him. On the reverse side of the note is a manuscript of the poem “Annabel Lee,” as its bearer declares, “That name’ll never be worth anything. Not in a hundred years.”

Of course, the audience watching this film almost exactly 100 years after Poe’s death knew better.

The most interesting plants grow in the shade

Which brings us to “The Pale Blue Eye,” in which Henry Melling portrays Cadet Poe, an outcast with a keen crime solver’s intellect. In a refreshing change, this younger Poe is not a tortured artist or a haunted, brooding figure. He is, however, picked on by his peers and underestimated by his superiors – yet again, an underdog viewers want to root for.

In that sense, the Poe in “The Pale Blue Eye” fits well with his contemporary image, which also permeates the early episodes of “Wednesday,” Netflix’s Addams Family spinoff set at Nevermore Academy that’s chock full of Poe references.

The headmistress of Nevermore Academy – a Hogwarts-like school for outcasts – refers to Poe as “our most famous alumni,” which explains why the school’s annual boat race is the Poe Cup and why there’s a statue of Poe guarding a secret passage.

The delightfully antisocial protagonist, Wednesday, played by Jenna Ortega, is an outcast among outcasts – the Poe figure at a school whose name evokes Poe. In one scene, a sympathetic teacher urges her not to lose “the ability to not let others define you. It’s a gift.” She adds, “The most interesting plants grow in the shade.”

When John Lennon sang “Man, you should have seen them kicking Edgar Allan Poe” in “I Am the Walrus,” he didn’t have to say who was kicking him or why. The point was, Poe deserved better; the most interesting plants do grow in the shade, unlovely and unloved.

And that’s exactly why so many people – aspiring writers and artists, but also everyone when they’re lonely and misunderstood – see a little bit of themselves in the weary-but-wise image of Poe.

Scott Peeples, Professor of English, College of Charleston

This article is republished from The Conversation under a Creative Commons license.