Supervolcano discovered at bottom of the Mediterranean

Scientists have discovered so-called 'megabeds' at the bottom of the Mediterranean Sea that appear to have been formed by ancient supervolcano eruptions.

Megabeds are huge submarine deposits that form in marine basins as a result of catastrophic events, mostly the result of volcanic eruptions.

These huge megabeds from ancient supervolcano eruptions were hiding at the bottom of the sea between Naples and Sicily, researchers have found. Their discovery points to a cycle of catastrophic events that appear to hit the region every 10,000 to 15,000 years.

The researchers found the megabeds while investigating deposits at the bottom of the Tyrrhenian Sea, near the coast of Italy, close to Marsili, a known large underwater volcano. Previous research into geohazards in the area using sediment cores and imaging indicated something was hidden beneath the ocean, but the resolution was not high enough to see the megabeds, explained lead study author Derek Sawyer, associate professor of Earth sciences at The Ohio State University.

In a new study, Sawyer and colleagues went back to the site to create higher-resolution images of the layers of sediment and discovered a succession of four megabeds, each between 10 to 25 meters thick, and each separated by distinct layers of sediments[1]. Cores drilled from the site showed the megabeds were made of volcanic material.

The oldest layer was around 40,000 years old, the next oldest was 32,000 years, the third 18,000 years, while the youngest formed about 8,000 years ago. Thus, the eruptions occurred roughly every 10,000 to 15,000 years.

The team then looked at known volcanic activity in the region to determine the source of the megabeds. The region where the beds formed is extremely active volcanically and includes the Campi Flegrei supervolcano, which has been quite active recently.

The oldest megabed formed after a huge eruption from Campi Flegrei ('burning fields'), situated to the west of Naples, around 39,000 years ago — one of the biggest known eruptions on Earth. The same eruption may also have created the second bed, as the layer between the two is just 1 meter — indicating a relatively short interval between the two events.

The scientists think the 18,000-year-old megabed formed in the wake of the Neapolitan Yellow Tuff supereruption of Campi Flegrei about 15,000 years ago, while the youngest megabed was deposited by another, less energetic eruption at Campi Flegrei.

The findings, Sawyer said, will help researchers understand the risk posed by volcanoes in the region. "That whole field is still active, there's still a lot of concern about the future of that, so it's certainly potentially possible that it could happen again," he said.

[1] Sawyer et al: 50,000 yr of recurrent volcaniclastic megabed deposition in the Marsili Basin, Tyrrhenian Sea in Geology - 2023. See here.

Santorini in danger (again)?

It has been quiet for nearly 400 years, but Kolumbo (κόλυμβη means 'diver'), an underwater volcano just off the Greek island of Santorini, is not asleep. In fact, Kolumbo is a sleeping menace.

[Kolumbo lies northeast of Santorini]

 

The last time Kolumbo erupted, in 1650, it killed 70 people, but population growth and tourism on Santorini could mean the impact of an unexpected equivalent eruption today could be far greater.

A previously undetected magma chamber is gradually filling with melt (molten rock), prompting researchers to recommend real-time monitoring of the volcano[1]. The melt reservoir extends from about two to at least four kilometers below sea level. The chamber coincides with the termination point of the recent earthquake swarms and may be a missing link between a deeper melt reservoir and the high-temperature hydrothermal system venting at the crater floor[2].

[Kolumbo, an underwater volcano]

 

Kolumbo belongs to the highly explosive family of volcanoes, capable of producing an eruption column tens of kilometres high. It is also liable to trigger a tsunami, making it a highly dangerous prospect. Using a new imaging technique, rather similar to a medical ultrasound, Kajetan Chrapkiewicz, and his colleagues spotted melt gathering roughly two miles beneath the volcano[3]. Their conclusions suggest that, although an eruption is not imminent, the volcano does pose a serious threat.

While Kolumbo is situated just 15 kilometers to the northeast of the center of Santorini caldera, the magmatic systems of Kolumbo and Santorini are unrelated and Kolumbo taps a distinct enriched mantle source[4].

The last eruption of Santorini was between 1600 and 1525 BC. That eruption buried the Minoan settlement on the island in a layer of ash and pumice more than 40 meters deep. The effects of the eruption were felt as far away as Egypt and it heralded the end of the Minoan civilisation. It is now understood that this eruption was the basis of the myth of Atlantis.

[1] Chrapkiewicz et al: Magma Chamber Detected Beneath an Arc Volcano With Full-Waveform Inversion of Active-Source Seismic Data in Geochemistry, Geophysics, Geosystems – 2022. See here.
[2] Schmid et al: Heralds of Future Volcanism: Swarms of Microseismicity Beneath the Submarine Kolumbo Volcano Indicate Opening of Near-Vertical Fractures Exploited by Ascending Melts in Geochemistry, Geophysics, Geosystems – 2022. See here.
[3] Paulatto et al: Advances in seismic imaging of magma and crystal mush in Frontiers in Earth Science - 2022. See here.
[4] Klaver et al: A distinct source and differentiation history for Kolumbo submarine volcano, Santorini volcanic field, Aegean arc in Geochemistry, Geophysics, Geosystems – 2016. See here.

Wolf Volcano (Galápagos) erupts unexpectedly

The entire Galápagos Archipelago has been formed by volcanic activity. This same activity continues to mold the islands to this day.

In the early hours of January 7, 2022, Wolf Volcano* on Isabela Island, the largest island of the archpelago, erupted without any warning. A joint team of conservation scientists were stationed on the rim of the volcano at the time of the eruption as part of an expedition to study and protect the critically endangered Pink Land Iguana (Conolophus marthae).

Fortunately, the conservation team’s field camp was located a safe distance from where the eruption occurred. Though they were in no imminent danger, the group was airlifted from the volcano by a private helicopter launched from the yacht 'Octopus' that was moored off the island.

At this point, the scientists believe that the habitat of the Pink Land Iguana remains unaffected by the volcanic activity, and as of now no additional actions are needed to protect this species. However, they will not be able to confirm this hope until they can safely conduct return expeditions to Wolf Volcano to fully assess the impacts of the eruption.

As an aside, The natural habitat on and around Wolf Volcano is under threat from the introduction of goats. So many other vulnerable habitats are olso under threat from goats. The Galapagos National Park has instituted Project Isabela to eradicate feral goats from around Wolf Volcano.

* No, there are no, nor have there ever been, wolves on the Galápagos Archipelago. The volcano is named after Franz Theodor Wolf (1841-1924), a German naturalist who studied the Galápagos Islands during the late nineteenth century. Nearby Wolf Island, also known as Wenman Island, is also named after him.

Source.

Japan has a (temporary) new island

An underwater volcanic eruption near Japan has created a new, roughly crescent-shaped island some 1,200 kilometers south of Tokyo - although the new landmass will likely only be temporary. According to the Japan Meteorological Agency, the submarine eruption — the volcano’s first in over a decade — began on August 13, 2021.

Niijima (新島), meaning 'new island', has a diameter of 1 kilometre and has emerged five kilometres north of Minami-Iōtō (南硫黄島), better known as South Iwo Jima or New Sulfur Island, amid the Nanpō Islands (南方諸島) that lie south of the Japanese archipelago.

The island formed as a result of a powerful eruption of Fukutoku-Okanoba, a submarine volcano which was only discovered when it erupted in 1904. The eruption produced a spectacular mushroom plume of steam and ash up to 16 kilometres altitude, quickly created a new cone that has now breached the surface.

When the eruption reached the surface, it created violent steam explosions as hot magma interacted with the surrounding sea water (known as phreatomagmatic or Surtseyan activity), ejecting billowing white steam plumes and dark jets of water, steam and rock fragments.

The last confirmed eruptions of the volcano occurred in 2010, 2005-07, 1986, 1914, and during 1904-05. During some of these, temporary islands were formed that subsequently were eroded again by the relentless waves of the ocean.

Whether the new island will become a lasting one will depend on the near future. At the moment, it has a flat crescent-shape with a breached bay above the vent and seems to be composed only of fragmented material (ash and blocks), which are not stable enough to resist wave erosion for too long. If activity continues and produces lava flows that manage to “seal” some of the new land, its chances of long-term survival will increase greatly.

Taal Volcano: Large Eruption Imminent (VEI 4-6)

The highest-ever levels of volcanic sulfur dioxide (SO₂) gas emissions and tall, steam-rich plumes were recorded venting from the Taal volcano’s main crater.

On Saturday, July 3, 2021, the Philippine authorities said sulfur dioxide (SO₂) emissions averaged 14,699 tonnes over the course of the day (an all-time high) while upwelling in the Main Crater Lake generated steam plumes that rose 2,500 meters above the volcano on the island near Luzon, the Philippines.

The next day, Sunday, July 4, 2021, Taal’s SO₂ venting had increased to 22,628 tonnes over a 24-hour period — another new all-time high.

A number of 'strong and very shallow' low frequency volcanic earthquakes associated with magmatic degassing have been recorded beneath the eastern part of the Volcano Island. The Taal Volcano Network recorded 17 volcanic earthquakes, including one volcanic tremor event having a duration of 45 minutes, 16 low frequency volcanic earthquakes, and low-level background tremor that has persisted since 8 April 2021.

As sulfur dioxide can cause irritation to the respiratory system, thousands are evacuated from the Taal Volcano Island, as well as from nearby high-risk regions. Authorities have raised the alert level accordingly, suggesting that magma is at or near the volcano’s surface. Several phreatomagmatic eruptions were also recorded. These are volcanic eruptions resulting from interaction between magma and water.

The Taal volcano has an explosive and catastrophic history. The most recent VEI 4 occurred in January, 2020. This eruption displaced hundreds of thousands of people and lead to the closure of Manila Airport. Volcanologists are expecting another eruption of at least VEI 4, but an VEI 6 is also dreaded. The explosive effects of the latter can be equated with those of the explosive eruption of Krakatoa in 1883.

A VEI 6 eruption would bring about a near instant cooling of the planet due to the sunlight-blocking particulates ejected high into the stratosphere. However, even a smaller eruption may have an impact on the earth's climate.

Volcanoes could still be active on Mars

Mars, the red planet, is a dead planet. For billions of years nothing has happened, except the occasional dust storm. That's what astronomers believed. Until now.

Astronomers had long believed that much of the planet's volcanic activity occurred between 3 and 4 billion years ago.

Now, orbiters circling Mars have provided imagery and data of a previously unknown area of interest. This latest information shows evidence of volcanic activity that must have happened within the last 50,000 years[1]. That is extremely young, astronomically speaking.

A smooth, dark area stretches for more than 10 kilometres. It's surrounded by a 30 kilometres-long volcanic fissure in the Cerberus Fossae system of faults where the Martian crust has pulled apart. This intriguing feature is located in the Elysium Planitia region, a plain spread across the planet's equator and second largest volcanic region.

"This may be the youngest volcanic deposit yet documented on Mars," said lead-author David Horvath, a research scientist at the Planetary Science Institute, in a statement. "If we were to compress Mars' geologic history into a single day, this would have occurred in the very last second."

The researchers believe the evidence, including how the material was distributed on the surface, matches a pyroclastic eruption. This type of volcanic eruption occurs when magma explodes due to expanding gases.

"When we first noticed this deposit, we knew it was something special," said study co-author Jeff Andrews-Hanna, an associate professor at the University of Arizona Lunar and Planetary Laboratory, in a statement. The deposit was unlike anything else found in the region, or indeed on all of Mars, and superficially similar resembles featuresinterpreted as pyroclastic deposits on the Moon and Mercury."

Most of the evidence of previous volcanic activity is similar to lava flows that we might see on Earth. But this one is different.

"This feature overlies the surrounding lava flows and appears to be a relatively fresh and thin deposit of ash and rock, representing a different style of eruption than previously identified pyroclastic features," Horvath said. "This eruption could have spewed ash as high as 10 kilometres into Mars' atmosphere. It is possible that these sorts of deposits were more common but have since been eroded or buried."

[1] Horvath et al: Evidence for geologically recent explosive volcanism in Elysium Planitia, Mars in Icarus. See here.

A new volcano near Mayotte

Although it is a popular tourist destination, most of you will not know that Mayotte is an island in the Indian Ocean. It is part of France as an overseas department and region. While geographically a part of the Comoros archipelago, located off the coast of Southeast Africa, it is politically not part of it.

Mayotte consists of two islands, Maore (or in French Grande-Terre), the smaller Pamanzi (or in French Petite-Terre) and some smaller islets scattered around the main islands.

The archipelago is a primarily volcanic, rising steeply from the bed of the ocean to a height of 660 metres. Two volcanoes are looming on the main island; the Pic Chongui in the south and Mont M'Tsapéré in the north. Both are dormant and the last eruption is thought to have occurred some 7,000 years ago.

The quiescence of the islands was rudely disturbed on May 10th, 2018 with a series of earthquakes. A magnitude-5.8 earthquake, the largest ever recorded in the Comoros basin, struck just off the coast five days later. A research programme was carried out to try to understand the origin of those quakes. The research focused on a nascent underwater volcano discovered in May 2019, some 50 kilometres east of the island of Mayotte and at a depth of 3,500 meters.

The research mapped the volcanic ridge between the active volcano and the seismic zone (about 15 kilometres from the island). Seismic activity has now decreased.

The data collected confirms that the height of the volcano has not changed (its peak is at a depth of 2,850 meters). On the other hand, since June 2019, a new lava flow has been identified on the western flank of the underwater volcano. It is more than 150 metres thick. Its estimated volume is 0.3 square kilometres.

The undersea volcano was spewing volcanic material to a height of two kilometres, but the lava could not reach the surface of the ocean. The volcano is linked to a rapid rate of shifting and sinking of Mayotte. The sinking on the island’s east end has reached 13 centimetres since July 2018.

The volcano and the sinking of the island could herald death and destruction. The meaning of its local (and original) name of Maore was almost prophetic, because the name is believed to originate from Arabic Jazīrat al-Mawt (جزيرة الموت), meaning 'island of death'. Although some speculate that the name was chosen because of the dangerous reefs that surround the islands.

An Alaskan Caldera System?

Like a string of pearls, the Aleutian Islands connect Alaska to Siberia. But these are dangerous pearls, because they are part of the so-called Ring of Fire that encircles the Pacific Ocean. Therefore, numerous volcanoes can be found on these barren islands.

[Volcanoes from bottom to top: Tana, Herbert, Cleveland, Carlisle]

The Islands of the Four Mountains in the central Aleutians harbour six stratovolcanoes named Carlisle, Cleveland, Herbert, Kagamil, Tana and Uliaga. New evidence suggests that this cluster may be an interconnected giant volcano.

Researchers have been studying Mount Cleveland, the most active volcano of the group, trying to understand the nature of the Islands of the Four Mountains. They have gathered multiple pieces of evidence showing that the islands could belong to one interconnected caldera[1].

The researchers mapped the sea floor of the region and discovered several curved structures on the sea floor. A depression more than 400 feet deep was seen that may be part of the caldera.

[A massive caldera]

A caldera is created by tapping a huge reservoir in the Earth’s crust. When the reservoir’s pressure exceeds the strength of the crust, gigantic amounts of lava and ash are released in a catastrophic episode of eruption.

If the researchers’ suspicions are correct, the newfound volcanic caldera would belong to the same category of volcanoes as the Yellowstone Caldera and other volcanoes that have had super-eruptions with severe global consequences.

Caldera-forming eruptions are the most explosive volcanic eruptions on Earth and they often have had global effects. The huge amounts of ash and gas they put into the atmosphere can severely affect Earth’s climate and trigger social upheaval. For example, the eruption of nearby Okmok volcano in the year BCE 43 has been recently implicated in the disruption of the Roman Republic[2].

Diana Roman, co-author of the study, and her team have collected a range of evidence, including gravity anomalies from satellite data and bathymetric surveys that were conducted in the area shortly after World War II.

If their suspicions are confirmed, the team believes that the potential underwater basin may have resulted from a volcanic explosion that was just shy of earning the label 'super eruption.'

[Update] At first, I called this system a 'supervolcano', but Diana Roman kindly contacted me to explain that the term is overused, misrepresentative, and misapplied. Instead, she suggests, I should call it 'caldera system'. See here. Which I agree with and which also explains the altered title of this post.

[1] Power et al: Multi-Disciplinary Evidence for a Large, Previously Unrecognized Caldera in the Islands of Four Mountains, Central Aleutian Arc, Alaska in AGU Fall Meeting – 2020
[2] McConnell et al: Extreme climate after massive eruption of Alaska’s Okmok volcano in 43 BCE and effects on the late Roman Republic and Ptolemaic Kingdom in PNAS - 2020

Lava lake rises (again) in African Nyiragongo volcano

In 2002, the last time Nyiragongo volcano erupted, lava raced down its flanks into the crowded city of Goma, on the border between the Democratic Republic of the Congo and Rwanda. About 250 people died, 20% of the city was destroyed, and hundreds of thousands fled. Since then, the at-risk population living in the shadow of the volcano has more than doubled to 1.5 million.

[Nyiragongo volcano in 2020]

The 2002 eruption began after an earthquake opened up fissures in the southern flank of the volcano. The 200-meter-wide lava lake, the largest in the world, drained in a matter of hours, releasing low-silica, runny lava that flowed as fast as 60 kilometers per hour. The lava piled up in layers up to 2 meters deep in Goma and created a new delta 800 meters wide in nearby Lake Kivu.

As soon as the fissures healed, however, fresh lava began to bubble up and refill the crater lake. Activity accelerated in 2016 when a second vent began to fountain within the crater. In February 2020, Dario Tedesco, a volcanologist, led an expedition into the volcano’s crater. They found the lake rising faster than ever. The second vent was gushing an estimated 4 cubic meters of lava per second, enough to fill an Olympic swimming pool every 10 minutes. Their analysis suggests peak hazard will arrive in four years, although they believe an earthquake could trigger a crisis earlier.

[Goma in 2020]

 They believe the system may be reaching a critical point, as it did before the 2002 eruption and an earlier one in 1977. In both cases lava lake levels stabilized several years before the eruption, they argue, as the mass of molten rock weighed down on the magma below. But swarms of small earthquakes or ground deformation are clearer warning signs of restless magma. Cynthia Ebinger, an expert on Rift Valley geology says the stretching of tectonic plates in the region leads to earthquakes and fresh intrusions of magma that can also trigger eruptions.

A network of seismometers around the volcano shows high earthquake activity and several deep swarms. Scientists do not know how unusual the activity is because they lack comparable, older data. But sustained, rumbling tremors were recorded months before the 2002 eruption. Nothing like that is detected for the moment.

The network requires constant maintenance, because of vandalism, theft, and lightning damage. Several seismometers are currently out of action.

[Update 23 May 2021]: Nyiragongo Volcano Erupts to 45,000 feet: DR Congo Orders Citywide Evacuations. See here.

Cenotes in the Arctic?

A cenote is a natural sinkhole created where a cave ceiling has collapsed. These caves were formed by the slightly acidic rainfall dissolving the alkaline limestone. The best known examples of cenotes are those which are the result of the impact of the meteorite that impacted Mexico's Yucatan peninsula some 65 million years ago and ended the reign of the dinosaurs.

Mexico's Yucatan peninsula is low and relatively flat with no surface rivers or streams. However all that tropical downpour would need to find a way to reach the Caribbean. The water runs via several of the longest underground rivers in the world, Sac Actun (353 kilometers), Ox Bel Ha (270 kilometers) and Dos Ojos (85 kilometers). The underground rivers have sustained humans in the last 13,000 years.

Cenote water is often very clear, as the water comes from rain water filtering slowly through the ground. Cenotes were the only source of water for the Mayan civilization and are considered sacred by the Mayan people. The Mayan considered cenotes to be an entrance to their underworld or Xibalba where their gods live and their spirits reside after death.

The word cenote is derived from the Mayan word tsʼonot and refers to any subterranean chamber that contains permanent water. While some cenotes are vertical, water-filled shafts, others are caves that contain pools and underwater passageways in their interior.

The term cenote has also been used to describe similar karst features in other countries such as Cuba and Australia, in addition to the more generic term of sinkholes.

Now, features resembling cenotes are appearing in the northern Siberian permafrost. These cenotes appear because methane gas-saturated cavities are formed in the permafrost. When the pressure of the gas rises, explosions can occur in swelling pingos. The largest is 50 meters deep[1].

Scientists like to call these features hydrolaccoliths. The phenomenon was first observed in 2014 and is the direct result of global warming and activities like drilling for oil.

I wonder if these spectacular methane explosion craters also formed in the last interglacial during periods of warming? It seems to me that hey would have been the ultimate woolly mammoth trap.

[1] Anna Liesowska: Giant new 50-metre deep 'crater' opens up in Arctic tundra in Siberian Times - 29 August 2020. See here.

Taal (Philippines) eruption may trigger El Niño

The Taal caldera is largely filled by Lake Taal, whose 267 square kilometers surface lies only 3 meters above sea level. All historic eruptions took place from a five kilometers wide volcanic island in the northern-central part of the lake.

[Lake Taal]

When the Taal volcano near Manila (The Philippines) started erupting on January 12, 2020, ash spewed 14 kilometers into the air, coating villages in a blanket of dust and affecting nearly 460,000 people, many of whom lost access to electricity and fresh water. Despite the significant impact, the eruption so far has been tame compared to some of the biggest eruptions in history.

Climatologists think that, if the ongoing Philippine volcanic eruption does become more violent, the gases released are likely to trigger an El Niño event during the 2020-21 winter, a more intense polar vortex and considerable warming across Eurasia.

Fine ash and sulfur dioxide from eruptions will block incoming solar radiation, thus reducing heat at Earth's surface that in turn produces atmospheric warming. As a result, for a year after especially violent eruptions, temperatures can be cooler than normal across much of the planet. But in addition to the cooling, there can also be a warming in the first post-eruption winter in the northern hemisphere as surface temperatures rebounds.

Researchers took data on the scale of volcanic eruptions worldwide over the past 1,100 years taken from Greenland and Antarctica ice cores and entered this into global climate models. This then allowed them to project the impact of the Taal eruption[1].

They think there is a high likelihood (83% probability) of an El Niño-like warming event during the 2020-21 winter if the magnitude of the Taal eruption reaches a mid-range "volcanic explosive index". Such an eruption would also produce an enhanced polar vortex— a large area of low pressure and cold air surrounding the Earth's North and South poles, which in turn would drive warming across the Eurasian continent.

[1] Liu et al: Could the Recent Taal Volcano Eruption Trigger an El Niño and Lead to Eurasian Warming? in Advances in Atmospheric Sciences - 2020

The Strange Case of the Missing Moon in AD 1110

In the year AD 1110, the night sky turned dark as the Moon completely disappeared from view. Not for a few days as is usual, but the disappearance lasted months, perhaps even for more than a year. Now, scientists may have the reasons as to what caused this strange phenomenon.

Somehow, somewhere, a huge upheaval occurred in Earth's atmosphere around a millennium ago: the skies turned dark after a massive cloud of sulfur-rich particles moved through the stratosphere, eventually reaching Earth and now trapped deep within ice sheets or glaciers of Greenland.

The ice has preserved this evidence and this results in incredibly long timescales, which helps scientists pinpoint exact dates of events that are visible in the layers of an ice core. It has now been confirmed that the Moon's disappearing act did actually occur, but different theories have been put forward over the years as to the exact cause.

Scientists had long assumed that the sulphurous deposit was left by a major eruption unleashed in AD 1104 by Iceland's Hekla. Since the thin strip of ice ranks among the largest sulfate deposition signals of the last millennium, it sounded quite plausible.

However, more recent research concluded that a timescale named the Greenland Ice Core Chronology 2005 (GICC05) was showing the incorrect dates for some of the events and was off for about seven years[1].

The GICC05 information is what lead the new research team led by Sébastien Guillet from the University of Geneva to deduce that it could not have been the Hekla volcano's eruption that led to that specific phenomenon[2]. The team then looked into medieval records that described dark lunar eclipses that could correspond to this event.

"The spectacular atmospheric optical phenomena associated with high-altitude volcanic aerosols have caught the attention of chroniclers since ancient times," the team writes in their paper. "In particular, the reported brightness of lunar eclipses can be employed both to detect volcanic aerosols in the stratosphere and to quantify stratospheric optical depths following large eruptions."

The researchers discovered that in AD 1108 another massive volcanic eruption occurred, when Japan's Mount Asama erupted. Combining credible witness accounts and observation of tree ring formations, and other historical documentation, the team suggests that this eruption could have lead to the strange occurrence.

These observations aren't proof enough to concretely say they lead to the occurrences, however, putting all the different information together has lead the scientists to believe these forgotten massive eruptions created huge consequences on humanity.

[1] Sigl et al: Timing and climate forcing of volcanic eruptions for the past 2,500 years in Nature – 2015. See here.
[2] Guillet et al: Climatic and societal impacts of a “forgotten” cluster of volcanic eruptions in 1108-1110 CE in Scientific Reports – 2020. See here.

Iceland volcanic region waking up?

Volcanic activity seems escalating in a region of Iceland that has not erupted for 800 years, with scientists warning it could cause disruption for centuries to come.

Since 21 January, 2020, the Reykjanes peninsula south-west of Iceland’s capital, Reykjavik, has experienced more than 8,000 smaller earthquakes and about 10 centimeters of land uplift due to magma intrusions underground.

Situated close to the town of Grindavík and only 15 kilometers from Iceland’s international airport, the region last erupted about 800 years ago (though there have been more recent eruptions offshore). Geological evidence shows the area is fed by five volcanic systems, which seem to come to life in a coordinated way roughly every 1,000 years.

The last period of volcanic activity on the peninsula lasted from the 10th century until the 13th. Unlike typical Icelandic volcanoes, which tend to wake for a few years and then die down, this region appears to splutter on and off for up to 300 years, producing eruptive episodes (locally known as 'fires') lasting a few decades. Long thin cracks (or fissures) extend up to 8 kilometers, producing fountains of lava, usually without large amounts of ash or explosive activity.

The most recent 'fires' occurred between 1210 and 1240 and covered about 50 sq km of land in lava. At least six separate eruptions occurred, each lasting weeks to months, interspersed with gaps of up to 12 years with no activity. Volcanic rock fragments and particles were carried tens of kilometres by the wind and written sources report the rockfall causing problems for livestock in the area.

Icelanders are used to volcanic activity, but they will be keeping a close eye on the Reykjanes peninsula. Because the eruptions are likely to be relatively small and occasional they will be easier to cope with than massive and sudden outpourings of lava like the 1783-84 Laki eruption, but if the pattern is indeed about to repeat, it will present a new kind of challenge for Icelanders.

Nisyros: A Sleeping Giant

An hour's trip by boat from the Greek island of Kos lies the volcanic island of Nisyros, part of a small archipelago. Nisyros is almost circular, with a diameter of about 8 kilometers. Four small villages dot the island.

The volcano of Nisyros started its life underwater, emerging from the sea about 150,000 years ago. Over the next 135,000 years, a series of eruptions both great and small shaped the island, more or less to its present form.

[On the rim of the caldera - Image: Erna de Vries]

The island has a caldera that is four by three kilometers wide. Two of the four villages are set precariously on its rim. Nikia (Νικια) offers a stunnnig view into the caldera which is home to no less than 20 hydrotermal craters. The largest is the approximately 4,000-5,000-year-old Stefanos. Elliptical in shape, with diameters of 330 meters and 260 meters, Stefanos is one of the largest and best preserved hydrothermal craters in the world. Its fumaroles are still puffing hydrogen sulfide and the boiling water vapour, which means that the volcano is currently active, but not erupting.

[Stafanos - Image: Erna de Vries]

Yes, hydrogen sulfide (H₂S) still smells of rotten eggs, as we are happy to report.

The caldera is such an alien landscape that the producers of James Bond found it the perfect location to suggest a lunar landscape for 'Moonraker'.

The population of Mandrake (Mανδρακι), the principal city, seems wary of visitors. Their smiles seem forced and their eyes are devoid of sincere happiness. Maybe that is the result of the silent menace of a volcano under your feet.

The legacy of Anak Krakatau

Anak Krakatau, located in Indonesia's Sunda Strait, is the name of the present-day volcano and means 'Child of Krakatoa', a nod to how it emerged in the aftermath of the historical eruption of 1883 that destroyed the island of Krakatoa.

On December 22, 2018, Anak Krakatau erupted following half a year of simmering volcanic activity. As a result of the eruption, two thirds of the original volcanic island, some 300 million cubic meters of rock, tumbled into the sea. That event caused 13 meter high tsunamis that flooded communities on both sides of the surrounding Sunda Strait, killing some 437 people.

Scientists have now created simulations to better understand how the island's explosion set off the catastrophic event[1]. They found that the landslip from Anak Krakatau fell into an unusually deep submarine trough to the southwest of, the bottom of which lay more than 200 metres beneath the ocean surface.

Forty volcanoes around the world could potentially trigger enormous tidal waves similar in size and strength to the devastating 13 meter high tsunami.

'One of the aspects of events such as Anak Krakatau is that we are now aware of a hazard hovering in the background and there are millions of people who live adjacent to volcanoes,' said marine geologist and first researcher David Tappin. 'Warning systems in all the world's oceans are predicated on large earthquakes. Volcanoes are still little understood,' he added.

Tappin cautions that there are at least 40 other volcanic sites that 'could be potential Anak Krakataus.'

[1] Tappin et al: The devastating eruption tsunami of Anak Krakatau - 22nd December in Geophysical Research aBstracts - 2019. See here.

Toba eruption and early humans in India

When Mount Toba erupted some 78,000 years ago, so much ash was released into the atmosphere that the entire Indian sub-continent was smothered in it. To this day the meters thick ash is 'mined' in Jwalapuram in southeastern India. Then, in 2007, a team of archeologists discovered some stone tools were under these levels of ash, suggesting that modern humans reached India at least 78,000 years ago[1]. That, however, was a lot earlier than scientists used to believe. Even professor Alice Roberts heralded the discovery in her television series (2009) and book (2010) 'The Incredible Human Journey'.

[Buy the book here]

But the exitement was short lived, because in 2013 new evidence emerged that refuted that very early date[2]. Scientists collected mitochondrial DNA samples from 817 volunteers all across the Eurasian subcontinent, while also reexamining the stone tools that had originally set off the debate.

In studying the mtDNA, the researchers concluded that modern humans had settled in the area no earlier than 55,000 to 60,000 years ago. The evidence indicated that early humans had settled along the coast first, only then traveled inland following rivers. Such a timeline indicates that modern humans didn't migrate to India untill well after the eruption of Mount Toba.

[Large cutting stone found in the ashes in Jwalapuram]

Meanwhile, other members on the team investigated the stone tools discovered by the earlier team and found that they were very likely the work of Neanderthals, not early modern humans. They note that the author of the original study claiming the stones had been made by early humans had already withdrawn the paper with the suggestion that the tools were likely made by an unidentified group of archaic people living in the area at the time.

Taken together, the team concluded that their findings should once and for all end the debate regarding the migration timeline for modern humans moving into India.

[1] Petraglia et al: Middle Paleolithic Assemblages from the Indian Subcontinent Before and After the Toba Super-Eruption in Science – 2007. See here.
[2] Mellars et al: Genetic and archaeological perspectives on the initial modern human colonization of southern Asia in PNAS – 2013. See here.

Did scurvy exacerbate the plague?

Plague, the dreaded infectious disease, that decimated the populations of cities, countries and empires. It is caused by the bacterium Yersinia pestis. The plague is generally spread by rats that carry infected fleas.

Several pandemics are known to have ravaged the historic world. Three main Yersinia pestis strains are recognised: (1) Yersinia pestis Antiqua, which caused the Justinian Plague (541–544 AD), but continued intermittently until ∼750 AD; (2) Yersinia pestis Medievalis, which caused the Black Death in Europe (1347–1351 AD) and included successive waves, such as the Great Plague (1665–1666 AD), until the 18th century; and (3) Yersinia pestis Orientalis, which emerged in China in the 1850s and erupted there in a major epidemic in 1894 before spreading across the world as a series of epidemics until the middle of the 20th century.

Plague outbreaks appear to be related to increased abundance of rodents and other mammals that serve as hosts for the fleas that then transmit the disease to humans. We know that the plague is partially seasonal: at the end of the harvesting season, rat populations drop because they don't have enough to eat[1][2]. As a result, fleas start looking for new hosts to bite, and so begin targeting humans.

Most plague pandemics are preceeded by dramatic weather events, causing misery and crop failures. The result was famine.

But in times of famine, there is hardly any food for both humans and rats. As prolonged bad weather was seen over entire continents, rat populations dwindle accordingly over these continents, explaining the extremely fast expansion of the plague.

The population was already weakened by famine, but the prolonged lack of fresh fruits and vegetables meant that Vitamin C deficiency would be astonishingly common and that would undoubtedly lead to rampant scurvy. Remember, it was not uncommon for over 80% of sailors to die from scurvy during long voyages, with a total of an estimated two million succumbing to it between 1500 and 1800.

It's a deadly combination: famine, scurvy and the plague. No wonder then that the Black Death is estimated to have killed 30–60% of Europe's total population. The plague was somewhat less common in parts of Europe that probably had some alternative vitamin C-rich food supplies, such as seeweeds[3] (...vitamins such as vitamin C are present in large amounts in Ulva lactuca (sea lettuce).... That means that the majority of the Basque Country, isolated parts of Belgium and the Netherlands would have a highter chance to survive.

[1] Eckert: Seasonality of plague in early modern Europe: Swiss epidemic of 1628—1630 in Reviews of Infectious Diseases – 1980
[2] Bacaër: The model of Kermack and McKendrick for the plague epidemic in Bombay and the type reproduction number with seasonality in Journal of Mathematical Biology – 2012
[3] MacArtain et al: Nutritional value of edible seaweeds in Nutrition Reviews - 2007

When was Thera (Atlantis) destroyed?

New analyses that use tree rings could settle the long-standing debate about when the volcano Thera on Santorini erupted by resolving still existing discrepancies between archaeological and radiocarbon methods of dating the eruption[1].

[Santorini's craters]

Thera’s explosive eruption on Santorini more than 3,400 years ago buried the Minoan settlement on the island in a layer of ash and pumice more than 40 meters deep. The effects of the eruption were felt as far away as Egypt and it heralded the end of the Minoan civilisation. It is now understood that the explosive eruption of Thera was the basis of the story of Atlantis.

Archaeologists have estimated the eruption as occurring sometime between 1570 and 1500 BC by using human artifacts such as written records and pottery. Other researchers estimate the date of the eruption to about 1600 BC using carbon-14 measurements from organic material found just below the layer of volcanic ash.

“The volcanic eruption represents one short moment in time,” Charlotte Pearson, an assistant professor of dendrochronology said. “If you can date precisely when that moment is, then whenever you find evidence of that moment at any archaeological site, you suddenly have a very precise marker point in time.”

[Santorini]

By counting annual rings of trees that lived at the time of the eruption, the team dates the eruption to someplace between 1600 and 1525 BC, a time period which overlaps with the 1570-1500 date range from the archaeological evidence. In 2020, new evidence was presented that could support an eruption date around 1560 BC[2].

Pearson and her colleagues used two different tree-ring chronologies from long-lived trees that were alive at the time of the Thera eruption. Salzer’s extensive work on long-lived bristlecone pines living in California and Nevada provided the 200 tree-ring samples representing each year from 1700 to 1500 BC. Brown provided 85 Irish oak annual tree-ring samples that spanned the same years.

Because Irish oaks and bristlecone pines add a growth ring every year, the rings laid down year-by-year represent an environmental history going back thousands of years in time.

A massive volcano such as Thera ejects so much material into the atmosphere that it cools the earth. For cold-climate trees such as Irish oaks and bristlecones, that exceptionally cold year shows up as a much narrower tree ring. Salzer’s work reveals at least four different years within the new radiocarbon age range for Thera where the bristlecone pines had exceptionally narrow rings that might indicate a huge volcanic eruption.

But, curiously, there also exists historical evidence about the date of the catastrophic eruption of Santorini. The Athenean statesman Solon (Σόλων) lived from ca. 630 until ca. 560 BC. Solon went on a 'fact-finding mission' to Egypt. The Egyptian priests told Solon that a great seafaring nation perished 9,000 years before Solon. Solon told the story to Critias the elder (ca 600 BC), who recounted the story to his grandson Critias the younger (460 BC to 403 BC)[3]. Plato later wrote that 'Critias when he told this tale of the olden time, was ninety years old, I being not more than ten'[4]. Obviously, the repeated recounting of the story added an extra zero to the original number of years. There was no civilisation to speak of 9,000 years before Solon. Somehow, 900 years became 9,000 years.

Solon visited Egypt around 600 BC. When you add the 900 years, you arrive at 1,500 BC, which is rather close to the dates from both the archaeological and dendrochonolical research.

[1] Pearson et al: Annual radiocarbon record indicates 16th century BCE date for the Thera eruption in ScienceAdvances - 2018
[2] Pearson et al: Securing timelines in the ancient Mediterranean using multiproxy annual tree-ring data in Proceedings of the National Academy of Sciences - 2020
[3] Welliver: Character, Plot and Thoughts in Plato's Timaeus-Critias 1977. Appendix
[4] Plato: Timaeus. See here.

Did Tambora eruption help defeat Napoleon at Waterloo?

On April 5 1815, Mount Tambora erupted on the Indonesian island of Sumbawa, killing some 100,000 people. The next year, 1816, became widely known as 'the year without a summer', as gases, ashes and dust drifted over the entire globe, reaching the stratosphere, where they remained long enough to create 'an enormous sun filter'.

The summer-less summer of 1816 even inspired writers, such as Mary Shelley who wrote Frankenstein, a gothic novel set in often stormy environments and gloomy weather conditions ('Yet I did not heed the bleakness of the weather').

Now, research seems to indicate that the effects of the eruption of Mount Tamboro were having a detrimental effect on the weather much quicker[1]. The eruptions can hurl this electrified ash much higher than previously thought into the atmosphere – up to 100 kilometres above ground. Very small electrified volcanic particles from eruptions can 'short-circuit' the electrical current of the ionosphere – the upper level of the atmosphere that is responsible for cloud formation. This ultimately leads to sudden formation of clouds.

These clouds brought heavy rains across Europe that contributed to Napoleon Bonaparte’s defeat at the Battle of Waterloo from 16 to 18 June 1815.

Author of the research, Dr Matthew Genge, explained: “Vigo Hugo in the novel 'Les Miserables' said of the Battle of Waterloo: "Had it not rained on the night of 17th/18th June 1815, the future of Europe would have been different …an unseasonably clouded sky sufficed to bring about the collapse of a World.”[2].’

[1] Genge: Electrostatic levitation of volcanic ash into the ionosphere and its abrupt effect on climate in Geology - 2018. See here.
[2] Wheeler, Demarée: The weather of the Waterloo campaign 16 to 18 June 1815: Did it change the course of history? in Royal Meteorological Society – 2005. See here.

Volcanic eruptions and the fall of the Roman Empire

Dendrochronology (or tree-ring dating) of the northern hemisphere now spans the past 7,600 years. Adverse weather conditions cause trees to grow slowly and that results in small tree rings. Various historical events, like volcanic eruptions, can be observed in those tree rings.

Vulcanic eruptions of AD 536 and 540 led to climate cooling and contributed to hardships of Late Antiquity societies throughout Eurasia, and triggered a major environmental event in the historical Roman Empire[1]. The period is known as Late Antique Little Ice Age (AD 536 – 660. Documents of that time describe the veiling of the solar radiation during and after AD 536, the sun was observed blue-colored, without brightness, spring without mildness and summer without heat[2].

A group of researchers has proposed the possibility of El Salvador's Ilopango, which is known to have erupted around 540 AD, but others think that there were two seperate erupting volcanoes.

[Ilopango - El Salvador]

What followed after these eruptions was a persistently low solar radiation in the entire northern hemnisphere that contributed to remarkably simultaneous outbreaks of famine and Justinianic plague in the eastern Roman Empire. An extended period of little light may make it difficult for humans to survive. The level of production of plants is dependent on the amount of available sunlight. Food production, i.e, farming and animal husbandry, rely on the same solar energy. Humans, meanwhile, become more prone to disease if they are not exposed to enough sunlight to produce vitamin D.

The new study tracks the correlation of carbon isotope variation and volcanic eruptions from the 19th century until recent years, and shows the dramatic reduction in available sunlight in AD 536 as well as between 541 and 544 AD. The unusually poor years coincide with the bubonic plague epidemic that devastated the Roman Empire. The epidemic caused by the Yersinia pestis bacterium began in 542 AD and killed approximately half of the inhabitants of what was then considered the Eastern Roman Empire. The plague spread through Europe, from the Mediterranean, possibly as far north as Finland, and had killed tens of millions of people by the 8th century.

Recent research shows that a vitamin D deficiency correlates with various infectious diseases[3]. Like Influenza or the plague.

[1] Helama et al: Volcanic dust veils from sixth century tree-ring isotopes linked to reduced irradiance, primary production and human health in Scientific Reports – 2018. See here.
[2] Stathakopoulos: Reconstructing the climate of the Byzantine world: State of the problem and case studies in People and Nature in Historical Perspective (pages 247–261) – 2003
[3] Gios et al: Vitamin D and Infectious Diseases: Simple Bystander or Contributing Factor? In Nutrients – 2017. See here.

Mount Etna is sliding towards the sea

Mount Etna is Europe's most active volcano, but it harbours an unexpected danger. Scientists have recently established that the whole structure on the Italian island of Sicily is edging in the direction of the Mediterranean at a rate of on average 14 millimeters per year. The volcano is sliding down a very gentle slope of 1-3 degrees[1]. This is possible because it is sitting on an underlying platform of weak, pliable sediments.

Lead author Dr John Murray and his team have placed a network of GPS stations around the mountain to monitor its behaviour. This instrumentation is so sensitive that it can detect millimetric changes in the shape of the volcanic cone. It has detected that the mountain is moving in an east-south-easterly direction, on a general track towards the coastal town of Giarre, which is about 15 kilometers away. At the current rate of speed, it will take Mount Etna roughly 100 million years to reach Giarre.

14 millimeters per year may seem small, that is 14 meters per century, but geological investigations elsewhere in the world have shown that extinct volcanoes that display this kind of trend can suffer catastrophic failures on their leading flank as they drift downslope. Stresses can build up that lead eventually to devastating landslides.

"I would say there is currently no cause for alarm, unless there is an acceleration in this motion," Murray said. "The thing to watch I guess is if in ten years' time the rate of movement has doubled - that would be a warning. If it's halved, I'd say there really is nothing to worry about."

[1] Murray et al: Gravitational sliding of the Mt. Etna massif along a sloping basement in Bulletin of Volcanology - 2018

Justinian Plague: Volcanic Winter or Comet Impact?

The Justinian Plague (541–542), named after emperor Justinian I (527-565), was a pandemic that afflicted the Byzantine Empire. The pandemic resulted in an estimated 25 to 50 million deaths in two centuries of its recurrence.

[Rabaul Volcano]

A global cooling in 536 AD, that preceded the plague, was possibly triggered by a major volcanic eruption that released immense amounts of ash and sulphur into the atmosphere. Two different volcanos are thought to be the culprit: Rabaul volcano (Papua New Guinea) and Lake Ilopango (El Salvador). Another theory is that the dust veil was due to a comet impact. Ice-core analysis of Greenland ice from between 533 and 540 AD do show high levels of tin, nickel and iron oxides from an extraterrestrial source in the dust layer[1].

The appearance of the dust veil in 536 AD had a major impact. Global cooling and colder summers caused crops to wither. Widespread famine ensued and this subsequently made the people of the time more susceptible to disease.

In 541 AD a mysterious illness began to appear on the outskirts of the Byzantine Empire. Victims were described as suffering from delusions, nightmares, fevers and swellings in the groin, armpits and behind their ears. The plague arrived in Constantinople, the capital of the empire, the following year. At its peak the plague was supposedly killing 10,000 people in Constantinople a day.

It had long been suspected that the Plague of Justinian was in fact bubonic plague, the cause of the infamous Black Death that also occurred in the 14th century. In 2012 it was finally confirmed that this was the case. A team of researchers analysed human remains from gravesites from the period and found the presence of Yersinia Pestis[1].

The Black Death was carried by rat fleas living on black rats. The infected rats and fleas travelled around the ports and trade routes of the Mediterranean via merchant ships.

The outbreak lasted less than 6 months in Constantinople but it is estimated that 40% of those living there died in that time period. The plague would reappear at periodic intervals over the next 300 years and it would eventually claim the lives of 25% of people living in the Mediterranean region. It is estimated that somewhere in the range of 25-50 million people died in total as a consequence of this catastrophic illness. The last recorded recurrence was in 750 AD, but by this time the outbreaks had become less virulent. The plague would then disappear from Europe completely until the 14th Century.

Whatever the cause of the Justinian Plague, be it volcanic or extraterrestrial, the course of human history was changed forever and Europe would not fully recover until the rise of the Renaissance.

[1] Rigby et al: A comet impact in AD 536? in News and Reviews in Astronomy and Geophysics - 2004. See here.
[2] Bos et al: Yersinia pestis: New Evidence for an Old Infection in PloS One - 201. See here.

Mount Toba eruption (~74.000 years ago) and southern Africa

Mount Tambora erupted in 1815 and has been responsible for a year without summer in 1816. The impact on the human population was dire – crop failures in Eurasia and North America, famine and mass migrations.

The eruption of Mount Toba, some 47.000 years ago, was a hundred times more massive than that of Mount Tambora[1]. The effects would have had a much larger, and longer-felt, impact on people around the globe.

The scale of the ash-fall alone attests to the magnitude of the environmental disaster. Huge quantities of aerosols injected high into the atmosphere would have severely diminished sunlight – with estimates ranging from a 25 to 90 percent reduction in light. Under these conditions, plants die-off, large herbivores starved and provided little sustenance to the predators, both carnivores and humans, that depended on them. The cycle repeated itself, year after year.

Recently archaeologists discovered microscopic glass shards (cryptotephra) characteristic of the ashfall from the Toba eruption in two sites (the Pinnacle Point rockshelter and an open air site some 10 kilometers away called Vleesbaai) on the south coast of South Africa[2]. The study also shows that along the food-rich coastline of southern Africa, humans thrived through this mega-eruption, perhaps because of the uniquely rich food regime on this coastline. Around 'neighbouring' Lake Malawi humans also thrived[3].

In the 1990s, scientists began arguing that this eruption of Mount Toba, the most powerful in the last two million years, caused a long-lived volcanic winter that may have devastated the ecosystems of the world and caused widespread population crashes, perhaps even a near-extinction event in our own lineage, a so-called bottleneck.

[1] Williams: The ∼73 ka Toba super-eruption and its impact: history of a debate in Quaternary International – 2012
[2] Smith et al: Humans thrived in South Africa through the Toba eruption about 74,000 years ago in Nature – 2018
[3] Lane et al: Ash from the Toba supereruption in Lake Malawi shows no volcanic winter in East Africa at 75 ka in Proceedings of the National Academy of Sciences of the United States of America - 2013

Third orangutan species developed near Mount Toba

Until very recently everybody thought that there were only two species of orangutan: the Bornean orangutan (Pongo pygmaeus) and the Sumatran orangutan (Pongo abelii). The Bornean species is divided into three subspecies.

But now, scientists have discovered that a group of orangutans, living in a high-elevation forest called Batang Toru in the mountainous region of Tapanuli on Sumatra, is in fact a seperate species[1].

Their DNA showed that Bornean orangutans, Sumatran orangutans, and the new species, Tapanula orangutan (Pongo tapanuliensis), comprise three distinct evolutionary lineages. Further analysis revealed that the oldest lineage belongs to the newest species. The Tapanula orangutan is more closely related to its counterparts from Borneo, across the sea, than to other orangutans living on the same island.

The genetic work suggests that several million years ago, orangutans moved from the South Asian mainland onto what is now Sumatra and occupied an area south of the Toba caldera. Around 3.3 million years ago, a group of them moved north to colonize the area north of Toba. While the two groups did interbreed from time to time, they would remain largely distinct.

Then, some 600,000 years ago, a second split occurred—this time between the original population south of Toba and the orangutans that went on to settle in Borneo. As ice ages progressed and sea levels changed, orangutans moved effortlessly between landmasses—which explains how the Batang Toru orangutans could be more closely related to those from Borneo.

Around 75,000 years ago, Mount Toba erupted, causing widespread destruction Perhaps not coincidentally, the genomic data indicates a population crash of orangutans around 75,000 years ago as well. Because the lava destroyed the surrounding rain forest, the orangutans living on either side of the volcano were permanently separated.

[1] Nater et al: Morphometric, Behavioral, and Genomic Evidence for a New Orangutan Species in Current Biology - 2017