Tag Archives: volcanic

Millipede death-trail.

“Prehistoric Pompeii” answers the question of when animals first moved on land

The discovery of a ‘prehistoric Pompeii’ is poised to rewrite what we knew about animals colonizing the land.

Millipede death-trail.

Close-up of a looping millipede death-trail.
Image credits Anthony Shillito.

A duo of geoscientists from the University of Cambridge reports that Ordovician strata in Borrowdale, a site in the Lake District area of England, don’t actually hold the earliest known animal footprints on dry land. In fact, the side bore witness to volcanic-ash-induced mass dying.

Ashes to ashes

Our best estimates of when animals first moved in on dry land come, unsurprisingly, from fossils. However, these aren’t your usual run of the mill fossils — rather, paleontologists rely on a special kind, known as trace fossils, for the job. These include the fossilized tracks, prints, slither marks, and all other manners of impressions left by ancient animals moving over soft ground. Places with significant such trace fossils are known as trackway sites.

Ordovician-era (about 455 million-year-old) strata in Borrowdale were believed to hold the earliest such trace fossils on dry land. This was actually pretty problematic, as it didn’t fit with the rest of the evidence. In all other known trackway sites, the earliest evidence of animals moving onto dry land comes from the Silurian period (cca. 420 million years ago)

Geoscientists Anthony P. Shillito and Neil S. Davies of the University of Cambridge studied the site in England and have finally managed to explain why. Trackways in the Borrowdale area haven’t captured animals living on land, they say — it shows a massive dying of millipede-like arthropods at the hands (particles?) of volcanic ash.

The fossilized tracks formed from volcanic ash settling underwater, the team explains, not within freshwater lakes or sub-aerial sands as previously believed. It “is actually a remarkable example of a ‘prehistoric Pompeii’,” says Shillito. In the course of their study, the team found 121 new millipede trackways, all within volcanic ash, with evidence for underwater or shoreline deposition.

Volcanic ash is particularly deadly for such animals — even modern arthropod communities, and particularly in water. The ash itself is made up of very small particles, ranging from under 2 mm to 1μm (a micron, or 1-millionth of a meter). These particles are also very hard — they’re basically ground volcanic glass. Because they’re so tiny, they can get inside anthropoids’ exoskeletons/shells and clump around soft tissue, especially breathing and digestive organs. Because they’re so hard and generally sharp, they wreak havoc on these organs, killing the animals via, quite literally, a thousand cuts.

Shillito and Davies noticed that most of the trails were extremely tightly looping — a feature which is commonly associated with “death dances” in modern and ancient arthropods, which first made them suspect they were looking at a massive dying rather than traditional trace fossils. This study, the authors say, overturns what is known about the earliest life on land and casts new light onto a key evolutionary event in the history of life on Earth.

“It reveals how even surprising events can be preserved in the ancient rock record, but — by removing the ‘earliest’ outlier of evidence — suggests that the invasion of the continents happened globally at the same time,” Shillito notes.

The paper “Death near the shoreline, not life on land: Ordovician arthropod trackways in the Borrowdale Volcanic Group, UK” has been published in the journal Geology.

Volcano eruption might have pushed Iceland towards Christianity

What do a volcanic eruption, a medieval poem, and a conversion to Christianity have in common? Well apparently, in Iceland — a lot.

Black basaltic sand and bright green moss, at the bottom of Eldgjá. Image credits: Borvan53 / Wikipedia.

The Eldgjá volcano holds two records. It features the largest volcanic canyon in the world, some 40 km long, 270 m deep and 600 m wide at its greatest, and it also boasts the largest flood basalt in historic time, with an estimated 18 km3 of magma poured out of the earth, covering around 800 km2.

A multidisciplinary team of scientists has used information from ice cores and tree rings to date this violent eruption, which took place around the spring of 939 and continued at least through the autumn of 940 — shortly after the island was colonized by Vikings an Celts.

The eruption must have had a tremendous impact on these early settlers. Lava floods are rare and spectacular eruptions, in which huge flows of lava engulf the landscape, destroying everything in its path.

“This places the eruption squarely within the experience of the first two or three generations of Iceland’s settlers,” said first author Dr Clive Oppenheimer of Cambridge’s Department of Geography. “Some of the first wave of migrants to Iceland, brought over as children, may well have witnessed the eruption.”

But the team wasn’t interested just in studying the eruption — they wanted to see what effect it had on people in Iceland and beyond. They found that a haze of sulfurous dust spread over parts of Europe, resulting in an exceptionally blood-red and weakened Sun in Irish, German and Italian chronicles of the time.

More tangibly, the eruption also caused a reduction in global temperatures, which was revealed by studies on tree rings. The evidence contained in the tree rings suggests the eruption triggered an extremely cold summer, one of the coldest in 1,500 years.

“In 940, summer cooling was most pronounced in Central Europe, Scandinavia, the Canadian Rockies, Alaska and Central Asia, with summer average temperatures 2°C lower,” said co-author Professor Markus Stoffel from the University of Geneva’s Department of Earth Sciences.

Tree rings. Image credits: Albert Bridge.

[panel style=”panel-success” title=”Dendrochronology” footer=””]Dendrochronology is the study of tree rings. As is common knowledge, many trees grow ‘rings’ each year. This can not only be used to date certain events, but also infer how if those years have been particularly hot, cold, dry, or wet.[/panel]

This had devastating effects, mostly on people in Iceland, but also for people all around the world. The volcano eruption shifted weather patterns, causing a harsh winter and destroying crops in many places.

“It was a massive eruption, but we were still amazed just how abundant the historical evidence is for the eruption’s consequences,” said co-author Dr Tim Newfield, from Georgetown University’s Departments of History and Biology. “Human suffering in the wake of Eldgjá was widespread. From northern Europe to northern China, people experienced long, hard winters and severe spring-summer drought. Locust infestations and livestock mortalities occurred. Famine did not set in everywhere, but in the early 940s we read of starvation and vast mortality in parts of Germany, Iraq and China.”

Interestingly, this dramatic eruption might have had another effect in Iceland: it brought it closer to Christianity. Iceland’s Christianization began in 999 and was formalized sometime in the 11th century. Iceland’s most celebrated medieval poem, Vǫluspá (‘The prophecy of the seeress’), which can be dated as far as 961, tells a story about the end of Iceland’s pagan gods and the coming of a new age: the age of a single god.

The Codex Regius, an Icelandic codex in which many Old Norse poems are preserved. Credits: Oppenheimer et al.

In the poem, the seeress prophesies the destruction of the gods, with fire and flood overwhelming heaven and earth and the gods fighting their final battles. This is the “fate of the gods” — Ragnarök. What researchers found is that the poem seems to be describing the eruption. Here are some translated lyrics:

The sun starts to turn black, land sinks into sea; the bright stars scatter from the sky.
Steam spurts up with what nourishes life, flame flies high against heaven itself.

All that might seem circumstantial (after all, they are common themes), but it is very reminiscent of an eruption. The poem goes further, talking about cold weather — and in Norse mythology, Ragnarök itself is followed by a very cold weather, reminiscent of a volcanic or a nuclear winter.

“With a firm date for the eruption, many entries in medieval chronicles snap into place as likely consequences – sightings in Europe of an extraordinary atmospheric haze; severe winters; and cold summers, poor harvests; and food shortages,” said Oppenheimer. “But most striking is the almost eyewitness style in which the eruption is depicted in Vǫluspá. The poem’s interpretation as a prophecy of the end of the pagan gods and their replacement by the one, singular god, suggests that memories of this terrible volcanic eruption were purposefully provoked to stimulate the Christianisation of Iceland.”

Journal Reference: Clive Oppenheimer et al “The Eldgjá eruption: timing, long-range impacts and influence on the Christianisation of Iceland” Climatic Change (2018). DOI: 10.1007/s10584-018-2171-9.

Surtsey Island.

Researchers will drill into one of Earth’s youngest islands to understand how land forms

 One of the world’s youngest islands will be drilled in an effort to understand how land forms on Earth.
Surtsey Island.

Surtsey island, as seen in 2001.
Image credits ICDP.

The tiny island of Surtsey wasn’t even there 50 years ago. This 1.3 square kilometer island was formed off Iceland’s southwestern coast somewhere between 1963 and 1967 by a series of volcanic eruptions. And next month, a team of scientists will drill two holes into the depths of this young land. Supported in part by the International Continental Scientific Drilling Program, this will be the most detailed look at newly-formed land, which researchers hope will help them understand how molten rock, cold seawater, and the underground biosphere interact.

Why here

Being so new, Surtsey could probably boast some of the wildest, most untouched environments currently on the planet. It’s a UNESCO World Heritage site, earmarked for scientific observation — mainly regarding the biogeographic evolution of new land as it’s being colonized by plants and wildlife.

One particular point of interest is to see how hydrothermal minerals fit into the island’s rocks. These are believed to be at the root of Surtsey’s resilience against the North Atlantic Ocean’s waves and could help engineers design stronger blends of concrete. Another is to see how underground flora feeds on the minerals contained in rocks and hot fluids — helping us understand the role of the deep crustal biosphere in the environments we see topside.

The first of the drill holes will run parallel to an 181-meter deep hole drilled in 1979, which the scientists will use to see how microbes on the island evolved over time. This has been monitored since it was first drilled and is now likely teeming with micro-organisms indigenous to Surtsey. The team plans to place five incubation chambers in the new hole, at different depths, let them stay for a year, then checking them for microbes that have moved in.

The landscape on Surtsey (Wikipedia).

A second drill will be set at an angle and will investigate the hot fluids percolating (flowing) through the volcanic cracks and craters that formed Surtsey. Information gleaned here will help geologists reconstruct the sub surface volcano system that built Surtsey. In the initial contact between seawater and hot magma, hydrothermal vents formed in the rock. It made them less porous and helped reinforce Surtsey’s shores against erosion. This places it in stark contrast to other volcanic islands, which get ground down by the waves pretty rapidly after formation. Getting a better idea of how these minerals evolved over time could help engineers create better, more resilient types of concrete.

If all goes according to plan, both holes will pass through the original 1960s ocean floor, at about 190m below sea level.

Iceland’s Coast Guard will start shuttling in the required 60 tonnes of equipment and supplies drillers will need on Surtsey, which they estimate will take around 100 helicopter flights. In accordance with UNESCO regulations, all waste will be removed from the island, including the sterilized seawater to be used as drilling fluid. Drilling will be performed 24 hours a day to keep the operation as short as possible, and only 12 people will be allowed on the island at a time. The rest of the team will stay on the neighboring island of Heimæy.

Volcanic crystals might predict next big eruption

Analysis of crystal formed in the molten rocks of a volcano might predict volcanic eruptions with as much as a year in advance, researchers claim.

Mixing Seismology and Petrology

Different types of seismic recording; volcanic eruptions cause harmonic tremors, different from any other ones. Via USGS

Drawing data from the volcanic activity of Mount Helens from 1980 through 1986, geologists found that iron- and magnesium-rich crystals grow before an eruption, and by far, the most rapid growth of such crystals took place 12 months before an eruption.

Most active volcanoes, before erupting, display specific patterns of seismicity; monitoring these events, as well as, ground deformations, gas emissions and changes in water level are the best thing we have so far in terms of predicting volcanic eruptions. However, while these methods provide good indications, such a technique, if perfected, would dramatically improve the odds of predicting such an event.

“Volcanoes tend to erupt in a similar cycle and have similar trends,” said Kate Saunders, a study author and geologist at the University of Bristol in England, in a telephone interview. “If we can work out their behavior, it allows us to know what to look for. We can better evaluate the monitoring signals.”

Analyzing igneous rocks

Igneous rocks are one of the three major types of rocks (along with sedimentary and metamorphic), formed through the cooling and solidification of magma. When these rocks cool slowly, below the surface, they form visible, specific, crystals. Among the minerals form through this process are orthpyroxenes, silicate minerals comprising of single chains of chemical tetrahedra.

Dr Saunders and colleagues studied zoned crystals of orthpyroxenes, which grow concentrically like tree rings within the magma body. What happens is that these zones have slightly different chemical compositions, reflecting physical and chemical changes in the magmatic chamber where they were formed, thus giving a good indication of volcanic processes and the geological time setting when they occur, much like the rings on a tree.

Forensic mineralogy

Zoned orthopyroxene - not with its real color. The colors show the zones with different chemistries

Researchers used a technique called diffusion chronometry applied to orthopyroxene crystal rims, showing that episodes of magma intrusion correlate temporally with recorded seismicity, providing evidence that some seismic events are related to magma intrusion. Diffusion chronometry works in an almost forensic fashion, and it can must be applied to more volcanoes, in order to verify if this feature is present in all volcanoes, or if this was just a unlikely chance. If it isn’t then researchers have just struck gold.

“Such a correlation between crystal growth and volcanic seismicity has been long anticipated, but to see such clear evidence of this relationship is remarkable.”, explained Dr. Saunders.

Source

Stunning picture and video from the Kilauea Eruption in Hawaii

Photo by Adrian Glover.

As I was telling you just earlier, the Kilauea volcano erupted, with a fissure throwing lava up more than 20 meters towards the sky in a dazzling display of volcanic power. The Hawaii eruption took place just after one of the volcano’s floors collapsed, thus creating the necessary conditions for lava to come out to the surface. This is great news to volcanologists and volcano loves throughout the world, especially as so far no lives were threatened and no significant damage was done.

 

More absolutely amazing videos which I highly recommend can be found at USGS

 

4 hottest volcano events of 2009

Boy 2009 passed quite quickly, but it didn’t go without a blast, that’s for sure ! I’m gonna show you some really amazing stuff that happened during 2009, most of which you probably have no idea of, and this is the first one from that series.

4th place (honorable mention): Mayon, Philippines

Photo by C.G. Newhall.

It may have happened just a week ago, but it was spectacular nonetheless. Mayon has been keeping everybody on their toes, despite not technically erupting: 50.000 people have been evacuated because of lava fountains flowing freely downhill, and geologists reported they expect a major boom during 2010.

Photo by Tryfon Topalidis.

The sights it created may be absolutely stunning, but trust me, Mayon is not the place you want to be the following year.

 

3rd place: Redoubt, Alaska

Photo by R. Clucas.

Since the beginning of the year, Redoubt had us wondering; it seemed certain it will make a boom, and the only question was how big it will be. Well, it wasn’t that big really, but any volcanic eruption (especially in the US) is definitively an event. It was also what you can call the first “digital” eruption, with updates being constantly posted on twitter, among other channels.

2nd place: Underwater eruptions, Tonga

The underwater eruptions were absolutely amazing, and good thing is no people were threatened by them.

 

1st place: Sarychev peak, Russia

Photo by The High Fin Sperm Whale.

Yep, it’s old Mother Russia that gets this award, though I’m not sure it’s one you’d be happy to receive. It was big enough to be seen from the ISS, and they took some stunning pictures. The eruption absolutely stunned all flights above the Pacific over the Kuril islands for weeks and despite taking place practically in the middle of nowhere, everybody (well, that’s an exaggeration really) got a good look at it.

Rift in African desert will become ocean

oceanic-rift

In 2005, a huge 35 mile rift broke the Ethiopian desert apart and immediately led to geological claims that a new ocean was appearing there because two parts of the African continent were being pulled apart. However, the claims were quickly dismissed as being too controversial. However, a new study published in the latest issue of Geophysical Research Letters comes to back that idea up as the birth of at least a sea there seems inevitable.

It has to be understood that we are talking in geological time here. The extremely active volcanic areas around the rift along the edges of the tectonic plate may suddenly break apart in large ‘pieces’ instead of slowly dividing little by little as initially predicted. This could prove really dangerous to the local population according toCindy Ebinger, professor of earth and environmental sciences at the University of Rochester and co-author of the study.

“This work is a breakthrough in our understanding of continental rifting leading to the creation of new ocean basins,” says Ken Macdonald, professor emeritus in the Department of Earth Science at the University of California, Santa Barbara, and who is not affiliated with the research. “For the first time they demonstrate that activity on one rift segment can trigger a major episode of magma injection and associated deformation on a neighboring segment. Careful study of the 2005 mega-dike intrusion and its aftermath will continue to provide extraordinary opportunities for learning about continental rifts and mid-ocean ridges.”

“The whole point of this study is to learn whether what is happening in Ethiopia is like what is happening at the bottom of the ocean where it’s almost impossible for us to go,” says Ebinger. “We knew that if we could establish that, then Ethiopia would essentially be a unique and superb ocean-ridge laboratory for us. Because of the unprecedented cross-border collaboration behind this research, we now know that the answer is yes, it is analogous.”

“We know that seafloor ridges are created by a similar intrusion of magma into a rift, but we never knew that a huge length of the ridge could break open at once like this,” says Ebinger. “Seafloor ridges are made up of sections, each of which can be hundreds of miles long. Because of this study, we now know that each one of those segments can tear open in a just a few days.”