Category: Volcanoes

Hidden World Of Undersea Volcanoes And Lava Flows Discovered Off Italian Coast

 

Hidden beneath the waves of the Tyrrhenian Sea near southwestern Italy lies a newfound volcanic mosaic dotted with geothermal chimneys and flat-topped seamounts.

This complex is new to both science and the planet, geologically speaking; it’s only about 780,000 years old. Scientists aren’t particularly surprised to find volcanism in the region, which is home to active volcanoes like Mount Vesuvius and Mount Etna. But the new complex is unusual because it was created by a rare kind of fault, said study leader Fabrizio Pepe, a geophysicist at the University of Palermo, in Italy.

“This is a very complex area,” Pepe told Live Science.

Restless region

The western Mediterranean is seismically restless because of the collision of three tectonic plates: the African, the Eurasian and the Anatolian. Making matters more complex is a small chunk of crust called the Adriatic-Ionian microplate, which broke off of the African Plate more than 65 million years ago and is now being pushed under the larger Eurasian Plate in a process called subduction. Mount Vesuvius is one of the volcanoes created by subduction.

Previously, scientists discovered a series of undersea volcanic arcs created by this tectonic unrest, starting near the Sardinian coast, with increasingly younger arcs southward and eastward. These arcs were like an arrow pointing ever farther eastward, prompting Pepe and his colleagues to search for an even younger arc about 9 miles (15 kilometers) off the coast of Calabria, called the “toe” of the “boot” of Italy.

There, based on seafloor mapping, seismic data and magnetic anomalies, the researchers found a 772-square-mile (2,000 square km) region of lava flows, volcanic mountains and hydrothermal chimneys; vents in the seafloor allow hot minerals to spew out and form chimney-like structures. They dubbed the new area the Diamante‐Enotrio‐Ovidio Volcanic‐Intrusive Complex, after three flat-topped seamounts (underwater mountains formed by extinct volcanoes) that dominate the seafloor.

STEP by step
Those fractures are what allowed magma to rise to the surface at the Diamonte-Enotrio-Ovidio complex, creating an undersea landscape of lava flows and mountainous volcanoes. These volcanic seamounts are now plateaus because they protruded from the ocean when the sea level was lower, and they eroded into their present, flat-topped shape, Pepe said.

The volcanic complex is inactive, but there are small intrusions of lava in some parts of the seafloor there, the researchers reported July 6 in the journal Tectonics. However, the area could become active in the future, Pepe said, and active volcanism is ongoing on the eastern side of the Tyrrhenian Sea. The researchers are working to build a volcanic risk map of the complex to better understand if it could endanger human life or property. They are also investigating the possibility of tapping the complex to produce geothermal energy.

Scientists Uncover Deep-Rooted Plumbing System Beneath Ocean Volcanoes

Cardiff University scientists have revealed the true extent of the internal ‘plumbing system’ that drives volcanic activity around the world.

An examination of pockets of magma contained within crystals has revealed that the large chambers of molten rock which feed volcanoes can extend to over 16 km beneath the Earth’s surface.

The new study, published today in Nature, has challenged our understanding of the structure of ocean volcanoes, with previous estimates suggesting that magma chambers were located up to 6 km below the surface.

Interconnected magma chambers and reservoirs are the key driver of the dynamics of volcanic systems around the world, so understanding their nature is an important step towards understanding how volcanoes are supplied with magma, and, ultimately, how they erupt.

Mid-ocean ridges in particular make up the most significant volcanic system on our planet, forming a roughly 80,000 km-long network of undersea mountains along which 75 percent of Earth’s volcanism occurs.

However, because these volcanoes are located under thousands of metres of water, and sometimes permanent sea ice, we are only just starting to understand what the subsurface architecture of these volcanoes look like.

It is known that magma plumbing systems exist below the Earth’s surface, which can be thought of as a series of interconnected magma conduits and reservoirs, much like the pipes and tanks that make up plumbing systems in a house, instead at mid-ocean ridges the tap is a volcano.

In their study, the team analysed common minerals such as olivine and plagioclase which grew deep within the volcanoes and were subsequently erupted from the Gakkel Ridge located beneath the Arctic Ocean between Greenland and Siberia.

These minerals act as tape recorders from which changes in the physical and chemical conditions of the environment within which they grew can be measured. Critically, the team were able to record what processes occurred and at what depths these minerals began to crystallise in magma reservoirs.

Lead author of the study, Ph.D. student Emma Bennett, from the School of Earth and Ocean Sciences, said: “To calculate the depths of magma reservoirs we used melt inclusions, which are small pockets of magma that become trapped within growing crystals at different depths in the magmatic system. These pockets of melt contain dissolved CO2 and H2O.

“Because the melt cannot dissolve as much CO2 at shallow pressure as it can at high pressure, we can determine what pressure the melt inclusion was trapped, and in turn work out the depth at which crystallisation occurred, by measuring the amount of CO2 in the melt inclusions.

“Put simply, crystal growth in a magmatic environment can be likened to the growth rings on a tree; for example, a change in the chemical environment will result in the growth of a new layer with a different crystal composition.

“By analysing multiple melt inclusions we can start to reconstruct the architecture of the magmatic system.”

The study was the first to use the mineral plagioclase as a proxy for the depth of magma reservoirs, with previous studies using the mineral olivine.

The results showed that magma plumbing systems at mid-ocean ridges extend to much greater depths than previously thought. Oceanic crust is normally only around 6 km thick, and conventionally magma chambers were thought of as being located here.

Yet the new data has shown that the plumbing system extends to at least 16 km depth, which means that the magma chambers that fed the Gakkel Ridge volcanoes are located much deeper down in the mantle.

Scientists Have Found a Way to Better Predict Where Volcanoes Will Erupt Next

Not every volcanic eruption is a Mount Vesuvius-like catastrophe, with rivers of fire and flying rock that rains down on unsuspecting Pompeiians.

Sometimes, volcanoes’ summits collapse, forming miles-wide depressions called calderas, which are peppered by eruptive vents. When rivulets of magma force their way out of these vents, those small eruptions can spew dangerous amounts of lava and gas.

But the locations and threat levels of these vents are difficult to predict – eruptions can sometimes occur miles from the caldera’s center. That leaves cities located on or near volcanic fields, like Naples, Italy, facing a constant risk of poisonous volcanic gas, ash, and explosive bursts of lava.

Now, however, a group of scientists have figured out how to accurately pinpoint where on a volcano’s surface or in a caldera’s volcanic fields these damaging vent eruptions are likely to occur.

“Calderas have fed some of the most catastrophic eruptions on Earth and are extremely hazardous,” the scientists wrote in a new study published Wednesday in the journal Science Advances. That hazard is often underestimated by local populations, they added.

Mount Kilauea in Hawaii, which erupted last year, is speckled with such vents. The eruptions forced nearly 1,500 people to flee their homes, CBS News reported.

“These vents have lava coming out of them like fountains, which then leaks across the landscape like a slug,” Eleonora Rivalta, the lead author of the study, told Business Insider.

The scientists hope that insights from their new model could help communities like Hawaii’s better prepare for and anticipate future eruptions.

Magma’s fickle pathways
Magma, the liquid or semi-liquid rock under the Earth’s crust, makes up most of our planet’s mantle (its intermediary layer). When magma pushes its way to the surface, that causes a volcanic eruption.

Magma likes to take the path of least resistance as it surges upward. So figuring out what that path is can enable scientists to predict where it will next breach our planet’s surface. That’s what Rivalta’s team set out to do.

The easiest path, the researchers found, is for magma to move through rocks that are more “stretched out” than their nearby counterparts – less compressed, in other words.

Although many geologists thought the path of least resistance would be through an existing pathway or fault, Rivalta’s team found that vents are often “single-use only”, meaning magma erupts through them once and never again.

Rivalta and her colleagues used these discoveries to make computer models of future magma paths to the surface. They compared the predictions of their model to the known eruptive behaviour of vents across Italy’s Campi Fleigrei, outside of Naples.

This 8-mile-wide active volcanic field – known as the “burning fields” – first erupted almost 50,000 years ago, though the most recent major eruption was in 1538.

Rivalta’s model accurately mapped Campi Flegrei’s 70 eruptions over the past 15,000 years, including the highly damaging Monte Nuovo eruption in 1538.

Predicting the next Yellowstone eruption
Between 1600 and 2017, 278,880 people around the world were killed by volcanic activity and the consequences of those eruptions, like starvation or tsunamis.

Since the 1980s, deaths related to volcanic eruptions have been rather limited, as geographer Matthew Blackett reported in The Conversation. This isn’t because scientists have gotten better at predicting eruptions – it’s a matter of chance, since recent eruptions have been far from heavily populated areas.

So Rivalta hopes to leverage her group’s new research to give cities like Naples more information about impending eruptions. She also wants to apply this new model to Mount Etna in Sicily, and use it to examine the supervolcano under Yellowstone National Park.

That enormous volcano last erupted more than 640,000 years ago. If it were to erupt again, the supervolcano would spew ash across thousands of miles of the US.

Following the Yellowstone volcano’s last eruption, it collapsed on itself, creating a 1,500-square-mile caldera that’s ripe for new appearances of magma.

“Yellowstone is a caldera with tons and tons of vents,” Rivalta said. “The question of where the next one might appear is very relevant to this caldera.”

Water Discovered For First Time In Recorded History Inside Halemaumau Crater

A small pond of water has been discovered inside the summit crater of Hawaii’s Kilauea volcano for the first time in recorded history, possibly signaling a shift to a more explosive phase of future eruptions.

The U.S. Geological Survey says that after a week of questions about a green patch inside Kilauea’s Halemaumau crater, researchers were able to confirm the presence of water on Thursday.

USGS scientist Don Swanson says the pond has grown in size over the past week.

Swanson says the bottom of the crater, which once housed Kilauea’s famed lava lake, is now below the water table and researchers believe the pond is coming from that groundwater.

Lava interacting with the water table can cause explosive eruptions.

Italy’s Etna Volcano Erupts On Sicily, Disrupting Flights

Europe’s biggest active volcano, Mount Etna, erupted early Saturday with fiery explosions and lava flows, the Italian National Institute of Geophysics and Volcanology said (INGV).

Plumes of ash prompted authorities on the island of Sicily to close the Fontanarossa and Comiso Airports in the city of Catania, local media reported.

La Repubblica newspaper said a Ryanair flight from Rome was diverted to Palermo on Friday night, while several flights were delayed from landing or taking off on Saturday.

Airport authorities said flights had returned to normal at 11 a.m. local time (0900 UTC), but stressed that there may still be disruptions and delays.

According to the INGV, the lava was spurting from one of the craters on the volcano’s desert-like southeastern face, and then traveling around 1.5 kilometers (1 mile) down a barren escarpment called the Valle del Bove (Ox Valley).

The most recent Etna activity follows an eruption in December as well as “lively spattering” recorded by the institute in June.

At 3,300 meters (10,826 feet), Etna is the largest active volcano in Europe.

‘Crystal Clocks’ Used To Time Magma Storage Before Volcanic Eruptions

The molten rock that feeds volcanoes can be stored in the Earth’s crust for as long as a thousand years, a result which may help with volcanic hazard management and better forecasting of when eruptions might occur.

Researchers from the University of Cambridge used volcanic minerals known as ‘crystal clocks’ to calculate how long magma can be stored in the deepest parts of volcanic systems. This is the first estimate of magma storage times near the boundary of the Earth’s crust and the mantle, called the Moho. The results are reported in the journal Science.

“This is like geological detective work,” said Dr Euan Mutch from Cambridge’s Department of Earth Sciences, and the paper’s first author. “By studying what we see in the rocks to reconstruct what the eruption was like, we can also know what kind of conditions the magma is stored in, but it’s difficult to understand what’s happening in the deeper parts of volcanic systems.”

“Determining how long magma can be stored in the Earth’s crust can help improve models of the processes that trigger volcanic eruptions,” said co-author Dr John Maclennan, also from the Department of Earth Sciences. “The speed of magma rise and storage is tightly linked to the transfer of heat and chemicals in the crust of volcanic regions, which is important for geothermal power and the release of volcanic gases to the atmosphere.”

The researchers studied the Borgarhraun eruption of the Theistareykir volcano in northern Iceland, which occurred roughly 10,000 years ago, and was fed directly from the Moho. This boundary area plays an important role in the processing of melts as they travel from their source regions in the mantle towards the Earth’s surface. To calculate how long the magma was stored at this boundary area, the researchers used a volcanic mineral known as spinel like a tiny stopwatch or crystal clock.

Using the crystal clock method, the researchers were able to model how the composition of the spinel crystals changed over time while the magma was being stored. Specifically, they looked at the rates of diffusion of aluminium and chromium within the crystals and how these elements are ‘zoned’.

“Diffusion of elements works to get the crystal into chemical equilibrium with its surroundings,” said Maclennan. “If we know how fast they diffuse we can figure out how long the minerals were stored in the magma.”

The researchers looked at how aluminium and chromium were zoned in the crystals, and realised that this pattern was telling them something exciting and new about magma storage time. The diffusion rates were estimated using the results of previous lab experiments. The researchers then used a new method, combining finite element modelling and Bayesian nested sampling to estimate the storage timescales.

“We now have really good estimates in terms of where the magma comes from in terms of depth,” said Mutch. “No one’s ever gotten this kind of timescale information from the deeper crust.”

Calculating the magma storage time also helped the researchers determine how magma can be transferred to the surface. Instead of the classical model of a volcano with a large magma chamber beneath, the researchers say that instead, it’s more like a volcanic ‘plumbing system’ extending through the crust with lots of small ‘spouts’ where magma can be quickly transferred to the surface.

A second paper by the same team, recently published in Nature Geoscience, found that that there is a link between the rate of ascent of the magma and the release of CO2, which has implications for volcano monitoring.

The researchers observed that enough CO2 was transferred from the magma into gas over the days before eruption to indicate that CO2 monitoring could be a useful way of spotting the precursors to eruptions in Iceland. Based on the same set of crystals from Borgarhraun, the researchers found that magma can rise from a chamber 20 kilometres deep to the surface in as little as four days.

The research was supported by the Natural Environment Research Council (NERC).

Volcano Erupts On Italian Island Of Stromboli, Killing One Person

A volcano on the Italian island of Stromboli erupted Wednesday, releasing hot trapped magma in a powerful explosion, killing one person and enveloping the popular tourist destination in ash, witnesses and local officials said.

The one fatality, believed to be a tourist, was killed by falling stones during a hike, a rescue service official said. A second person was injured.

Italian news agency ANSA says the blast sent about 30 tourists jumping into the sea for safety.

The unexpected eruption started fires on the western side of the small Mediterranean island, which lies north of Sicily, off the toe of Italy. Fire crews were being called in from nearby locations and a Canadair plane was already in action.

“We saw the explosion from the hotel. There was a loud roar,” said Michela Favorito, who works in a hotel near Fico Grande, on the east side of the island.

“We plugged our ears and after this a cloud of ash swept over us. The whole sky is full of ash, a fairly large cloud,” she told Reuters.

Fiona Carter, a British tourist on the island of Panarea, some 17 miles from Stromboli, heard the blast.

“We turned around to see a mushroom cloud coming from Stromboli. Everyone was in shock. Then red hot lava started running down the mountain towards the little village of Ginostra,” she told Reuters.

“The cloud got bigger, white and gray. It enveloped Ginostra and now the cloud has covered Stromboli entirely. Several boats set off for Stromboli,” she added.

According to the geology.com website, Stromboli is one of the most active volcanoes on the planet and has been erupting almost continuously since 1932.