From COSMOS Magazine: “Galactic cosmic rays could have produced Titan’s sand dunes”

Cosmos Magazine bloc

From COSMOS Magazine

18 October 2019
Richard A Lovett

1
The dark grains of sand on Titan are unlike those on Earth. Stocktrek Images

Sprawling fields of dark-coloured sand dunes on Saturn’s giant moon Titan may have been produced by eons of irradiation by galactic cosmic rays, scientists say.

The dunes, discovered by NASA’s Cassini spacecraft and the ESA’s Huygens lander, sprawl over 10 million square kilometres of Titan’s surface, an area about the size of the US, including Alaska. They reach heights of nearly 100 metres.

But their grains are not like Earth’s sands. Most probably they are made of a mix of water ice and complex organics, such polycyclic aromatic hydrocarbons (PAHs), which are composed of multiple carbon rings linked together.

Historically, scientists have believed that the dunes’ organic compounds were formed by the action of sunlight on methane and nitrogen in Titan’s thick atmosphere, via a photochemical process akin to that which creates smog in polluted cities. Over time, they thought, these smog-like particles gradually settled on Titan’s surface.

In a paper published the journal Science Advances, however, scientists from the University of Hawaii at Manoa discovered that similar materials could be formed via irradiation from galactic cosmic rays.

Galactic cosmic rays are an extremely powerful form of radiation that enters our solar system from interstellar space. Earth is largely protected by its magnetic field, says principle investigator Ralf Kaiser from the University of Hawaii at Manoa in Honolulu.

Titan has no such magnetic shielding, although its dense atmosphere – much denser than Earth’s – does block most of the radiation.

But if enough gets through that, over time, it has a major effect, Kaiser says.

In laboratory experiments, his team bombarded acetylene ice – a material known to exist on Titan – with high-energy electrons, which are a good stand-in for actual cosmic rays. They continued until the acetylene had received the equivalent of 100 years worth of space radiation falling on Titan’s surface.

They then cataloged the reaction products, discovering PAHs with up to three or four rings.

“This is against conventional wisdom,” Kaiser says, “because scientists think that to form aromatic structures you need high temperatures like combustion.”

But the energy from the cosmic rays was so intense that these compounds formed at temperatures far below that of Titan’s surface of -179 degrees Celcius.

The process, he adds, works very quickly, especially compared to geological time scales. “Lots of organic material could accumulate,” he says.

More importantly, he says, it also works in a vacuum. That means that other acetylene-containing bodies in the outer solar system could also have PAHs, a possible explanation for why some of them have mysterious dark patches of organic compounds on their surfaces.

Kaiser’s team hasn’t proven that cosmic rays are the only ways by which PAHs can be formed on Titan, says Ralph Lorenz, a planetary scientist at Johns Hopkins University’s Applied Physics Laboratory in Laurel, Maryland, who was not part of the study team. In fact, he says, there is evidence that these chemicals also exist in Titan’s atmosphere.

“[But] they’ve shown that the chemistry story doesn’t (completely) stop when material settles out of the atmosphere,” he says. “It is interesting that future processing on the surface by the (small) flux of cosmic rays is possible.”

Happily, Lorenz says, NASA recently green-lighted a return mission to Titan, called Dragonfly, scheduled for launch in 2026. “Dragonfly will initially land among sand dunes,” Lorenz says. “So it should find out.”

See the full article here .


five-ways-keep-your-child-safe-school-shootings
Please help promote STEM in your local schools.

Stem Education Coalition

#galactic-cosmic-rays-could-have-produced-titans-sand-dunes, #cosmos, #u-hawaii-manoa

From COSMOS Magazine: “Gas emissions discovered from interstellar comet”

Cosmos Magazine bloc

From COSMOS Magazine

07 October 2019
Richard A Lovett

Astronomers have detected gas emissions from a comet streaking into our Solar System from interstellar space.

The comet, named 2I/Borisov, was first spotted on 30 August by a Crimean amateur astronomer, and is only the second such interstellar interloper ever to be found.

1
An artist’s concept of the interstellar comet named 2I/Borisov. NASA/JPL

Gas emissions from it are a significant find because they allow scientists to use spectrographic methods to begin deciphering exactly what the comet is made of.

That wasn’t possible with 1I/’Oumuamua, the only other interstellar object to be caught traversing the Solar System, because ’Oumuamua was never seen to emit detectable amounts of gas.

“For the first time, we are able to accurately measure what an interstellar visitor is made of and compare it with our own Solar System,” says Alan Fitzsimmons, an astrophysicist at Queens University, Belfast, UK.

So far, the astronomers have detected only one gas being emitted by the comet, cyanogen (CN). They have also put an upper bound on the amount of another gas, diatomic carbon (C2), which would have been detectable if the comet was producing a lot of it.

What’s more, they’ve been able to measure the rate at which CN is being emitted into the comet’s tail and coma (the cloud surrounding its nucleus), as well as making estimates about the amount of dust the comet is producing.

Based on these figures and the normal rates at which comets of various sizes emit such materials, it appears that the comet’s nucleus measures somewhere between 1.4 and 6.6 kilometers in diameter, they say.

That makes it a lot bigger than ’Oumuamua, which appears to have been a cigar-shaped body with an average diameter of no more than 200 meters.

’Oumuamua was so small, in fact, that it was not detected until late in its passage through the Solar System, allowing only a two-week opportunity for detailed observation.

Borisov, on the other hand, is still on its way into the Solar System and will be visible until October 2020, Fitzsimmons’s team says in their paper, which has been submitted to the journal The Astrophysical Journal Letters.

But the most interesting thing is how ordinary Borisov appears to be. “If it were not for its interstellar nature, our current data shows that 2I/Borisov would appear as a rather unremarkable comet in terms of activity and coma composition,” Fitzsimmons’ team write.

So far, only a single gas has been discovered. “But that’s still one step further in understating the composition of the ‘exocomet,’ if you want to call it that,” says Humberto Campins, a planetary scientist from Central Florida University, Orlando, who was not part of Fitzsimmons’ team.

“And it is headed closer to the Sun, so we should have an opportunity to study it in more detail.”

See the full article here .


five-ways-keep-your-child-safe-school-shootings
Please help promote STEM in your local schools.

Stem Education Coalition

#gas-emissions-discovered-from-interstellar-comet, #astronomy, #astrophysics, #basic-research, #cosmology, #cosmos

From from the University of Melbourne and Australia’s ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D) via COSMOS: “The hunt for a 12-billion-year-old signal”

From

u-melbourne-bloc

From University of Melbourne

and

arc-centers-of-excellence-bloc

From ARC Centres of Excellence

via

10 September 2019
Nick Carne

1
In this image the Epoch of Reionization, neutral hydrogen, in red, is gradually ionised by the first stars, shown in white.
Paul Giel and Simon Mutch / UNIVERSITY OF MELBOURNE DARK-AGES REIONIZATION AND GALAXY OBSERVABLES FROM NUMERICAL SIMULATIONS (DRAGONS) PROGRAM

Astronomers believe they are closing in on a signal that has been travelling across the Universe for 12 billion years.

In a paper soon to be published in The Astrophysical Journal, an international team reports a 10-fold improvement on data gathered by the Murchison Widefield Array (MWA), a collection of 4096 dipole antennas set in the remote hinterland of Western Australia.

SKA Murchison Widefield Array, Boolardy station in outback Western Australia, at the Murchison Radio-astronomy Observatory (MRO)

The MWA was built specifically to detect electromagnetic radiation emitted by neutral hydrogen – a gas that made up most of the infant Universe in the period when the soup of disconnected protons and neutrons spawned by the Big Bang started to cool down.

Eventually those atoms began to clump together to form the very first stars, initiating the major phase in the evolution of the Universe known as the Epoch of Reionization, or EoR.

2
Epoch of Reionization. Caltech/NASA

“Defining the evolution of the EoR is extremely important for our understanding of astrophysics and cosmology,” says research leader Nichole Barry from the University of Melbourne and Australia’s ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D).

“So far, though, no one has been able to observe it. These results take us a lot closer to that goal.”

The neutral hydrogen that dominated space and time before and in the early period of the EoR radiated at a wavelength of approximately 21 centimetres.

Stretched now to somewhere above two metres because of the expansion of the Universe, the signal persists – and detecting it remains the theoretical best way to probe conditions in the early days of the Cosmos.

But that’s difficult to do, the researchers say, as the signal is old and weak and there are a lot of other galaxies in the way.

That means the signals recorded by the MWA and other EoR-hunting devices, such as the Hydrogen Epoch of Reionisation Array (HERA) in South Africa and the Low Frequency Array (LOFAR) in The Netherlands, are extremely messy.

UC Berkeley Hydrogen Epoch of Reionization Array (HERA), South Africa

ASTRON LOFAR Radio Antenna Bank, Netherlands

Using 21 hours of raw data, Barry and colleagues explored new techniques to refine analysis and exclude consistent sources of signal contamination, including ultra-faint interference generated by radio broadcasts on Earth.

The result was a level of precision that significantly reduced the range in which the EoR may have begun, pulling in constraints by almost an order of magnitude.

“We can’t really say that this paper gets us closer to precisely dating the start or finish of the EoR, but it does rule out some of the more extreme models,” says co-author Cathryn Trott, from Australia’s Curtin University.

“That it happened very rapidly is now ruled out. That the conditions were very cold is now also ruled out.”

The research was conducted by researchers from a number of institutions in Australia and New Zealand, in collaboration with Arizona State University, Brown University and MIT in the US, Kumamoto University in Japan, and Raman Research Institute in India.

See the full article here .


five-ways-keep-your-child-safe-school-shootings
Please help promote STEM in your local schools.

Stem Education Coalition

The objectives for the ARC Centres of Excellence are to:

undertake highly innovative and potentially transformational research that aims to achieve international standing in the fields of research envisaged and leads to a significant advancement of capabilities and knowledge
link existing Australian research strengths and build critical mass with new capacity for interdisciplinary, collaborative approaches to address the most challenging and significant research problems
develope relationships and build new networks with major national and international centres and research programs to help strengthen research, achieve global competitiveness and gain recognition for Australian research
build Australia’s human capacity in a range of research areas by attracting and retaining, from within Australia and abroad, researchers of high international standing as well as the most promising research students
provide high-quality postgraduate and postdoctoral training environments for the next generation of researchers
offer Australian researchers opportunities to work on large-scale problems over long periods of time
establish Centres that have an impact on the wider community through interaction with higher education institutes, governments, industry and the private and non-profit sector.

u-melbourne-campus

The University of Melbourne (informally Melbourne University) is an Australian public research university located in Melbourne, Victoria. Founded in 1853, it is Australia’s second oldest university and the oldest in Victoria. Times Higher Education ranks Melbourne as 33rd in the world, while the Academic Ranking of World Universities places Melbourne 44th in the world (both first in Australia).

Melbourne’s main campus is located in Parkville, an inner suburb north of the Melbourne central business district, with several other campuses located across Victoria. Melbourne is a sandstone university and a member of the Group of Eight, Universitas 21 and the Association of Pacific Rim Universities. Since 1872 various residential colleges have become affiliated with the university. There are 12 colleges located on the main campus and in nearby suburbs offering academic, sporting and cultural programs alongside accommodation for Melbourne students and faculty.

Melbourne comprises 11 separate academic units and is associated with numerous institutes and research centres, including the Walter and Eliza Hall Institute of Medical Research, Florey Institute of Neuroscience and Mental Health, the Melbourne Institute of Applied Economic and Social Research and the Grattan Institute. Amongst Melbourne’s 15 graduate schools the Melbourne Business School, the Melbourne Law School and the Melbourne Medical School are particularly well regarded.

Four Australian prime ministers and five governors-general have graduated from Melbourne. Nine Nobel laureates have been students or faculty, the most of any Australian university.

#arc-center-of-excellence, #astronomy, #astrophysics, #basic-research, #cosmology, #cosmos, #epoch-of-reionisation, #epoch-of-reionization, #radio-astronomy, #university-of-melbourne

From University of Technology Sidney via Cosmos: “Super corals can handle acid, heat and suffocation”

1

From University of Technology Sidney

via

Cosmos Magazine bloc

COSMOS Magazine

Emma F Camp
David Suggett

1
Resilient corals are offering hope for bleached reefs. Emma Camp

Climate change is rapidly changing the oceans, driving coral reefs around the world to breaking point. Widely publicised marine heatwaves aren’t the only threat corals are facing: the seas are increasingly acidic, have less oxygen in them, and are gradually warming as a whole.

Each of these problems reduces coral growth and fitness, making it harder for reefs to recover from sudden events such as massive heatwaves.

Our research, published in Marine Ecology Progress Series, investigates corals on the Great Barrier Reef that are surprisingly good at surviving in increasingly hostile waters. Finding out how these “super corals” can live in extreme environments may help us unlock the secret of coral resilience helping to save our iconic reefs.

3
Bleached coral in the Seychelles. Emma Camp, Author provided.

Coral conservation under climate change

The central cause of these problems is climate change, so the central solution is reducing carbon emissions. Unfortunately, this is not happening rapidly enough to help coral reefs, so scientists also need to explore more immediate [Nature Ecology & Evolution] conservation options.

To that end, many researchers have been looking at coral that manages to grow in typically hostile conditions, such as around tide pools and intertidal reef zones, trying to unlock how they become so resilient.

These extreme coral habitats are not only natural laboratories, they house a stockpile of extremely tolerant “super corals” [Global Change Biology].

What exactly is a super coral?

“Super coral” generally refers to species that can survive both extreme conditions and rapid changes in their environment. But “super” is not a very precise term!

Our previous research quantified these traits so other ecologists can more easily use super coral in conservation. There are a few things that need to be established to determine whether a coral is “super”:

What hazard can the coral survive? For example, can it deal with high temperature, or acidic water?

How long did the hazard last? Was it a short heatwave, or a long-term stressor such as ocean warming?

Did the coral survive because of a quality such as genetic adaption, or was it tucked away in a particularly safe spot?

How much area does the coral cover? Is it a small pocket of resilience, or a whole reef?

Is the coral trading off other important qualities to survive in hazardous conditions?

Is the coral super enough to survive the changes coming down the line? Is it likely to cope with future climate change?

If a coral ticks multiple boxes in this list, it’s a very robust species. Not only will it cope well in our changing oceans, we can also potentially distribute these super corals along vulnerable reefs [PNAS].

4
Some corals cope surprisingly well in different conditions. Emma Camp, Author provided.

Mangroves are surprise reservoirs

We discovered mangrove lagoons near coral reefs can often house corals living in very extreme conditions – specifically, warm, more acidic and low oxygen seawater.

Previously we have reported corals living in extreme mangroves of the Seychelles, Indonesia, New Caledonia – and in our current study living on the Great Barrier Reef. We report diverse coral populations surviving in conditions more hostile than is predicted over the next 100 years of climate change [Frontiers in Marine Science].

Importantly, while some of these sites only have isolated populations, other areas have actively building reef frameworks.

Particularly significant were the two mangrove lagoons on the Great Barrier Reef. They housed 34 coral species, living in more acidic water with very little oxygen. Temperatures varied widely, over 7℃ in the period we studied – and included periods of very high temperatures that are known to cause stress in other corals.

5
Mangrove lagoons can contain coral that survives in extremely hostile environments, while nearby coral reefs bleach in marine heatwaves. Emma Camp, Author provided.

While coral cover was often low and the rate at which they build their skeleton was reduced, there were established coral colonies capable of surviving in these conditions.

The success of these corals reflect their ability to adapt to daily or weekly conditions, and also their flexible relationship with various symbiotic micro-algae that provide the coral with essential resources.

While we are still in the early phases of understanding exactly how these corals can aid conservation, extreme mangrove coral populations hold a reservoir of stress-hardened corals. Notably the geographic size of these mangrove locations are small, but they have a disproportionately high conservation value for reef systems.

However, identification of these pockets of extremely tolerant corals also challenge our understanding of coral resilience, and of the rate and extent with which coral species can resist stress.

See the full article here .


five-ways-keep-your-child-safe-school-shootings
Please help promote STEM in your local schools.

Stem Education Coalition

UTS is a public university of technology defined by our support for the economic, social and cultural prosperity of our communities. We are measured by the success of our students, staff and partners and committed to research, innovation and the dissemination of knowledge of public value. We are, and always will be, an inclusive university.

UTS has a culturally diverse campus life and vibrant international exchange study and research programs that prepare graduates for the workplaces of today and the future. Our campus is in the heart of Sydney’s creative and digital precinct and alongside Sydney’s central business district. Continuing a 10-year period of major development, the ongoing transformation of the UTS campus will ensure we continue to maintain and develop a purpose- and sustainably-built campus to support innovation in education and research.

Our UTS 2027 strategy outlines our vision to be “a leading public university of technology recognised for our global impact” . Our purpose is to advance knowledge and learning through research-inspired teaching, research with impact and partnerships with industry, the professions and community. UTS is part of the Australian Technology Network of universities: a group of prominent universities committed to working with industry and government to deliver practical and professional courses.

With a total enrolment of over 44,000 students, UTS is one of the largest universities in Australia.

#super-corals-can-handle-acid-heat-and-suffocation, #applied-research-technology, #cosmos, #oceanography, #university-of-technology-sidney

Woods Hole Oceanographic Institute via COSMOS: ” Geology creates chemical energy”

From Woods Hole Oceanographic Institute

22 August 2019

Origin of a massive methane reservoir discovered.

1
The manipulator arm of the remotely operated vehicle Jason samples a stream of fluid from a hydrothermal vent.
Chris German/WHOI/NSF, NASA/ROV Jason 2012 / Woods Hole Oceanographic Institution

Scientists know methane is released from deep-sea vents, but its source has long been a mystery.

Now a team from Woods Hole Oceanographic Institution, US, may have the answer. Analysis of 160 rock samples from across the world’s oceans provides evidence, they say, of the formation and abundance of abiotic methane – methane formed by chemical reactions that don’t involve organic matter.

Nearly every sample contained an assemblage of minerals and gases that form when seawater, moving through the deep oceanic crust, is trapped in magma-hot olivine, a rock-forming mineral, the researchers write in a paper published in Proceedings of the National Academy of Science.
.

As the mineral cools, the water trapped inside undergoes a chemical reaction, a process called serpentinisation, which forms hydrogen and methane.

“Here’s a source of chemical energy that’s being created by geology,” says co-author Jeffrey Seewald.

On Earth, deep-sea methane might have played a critical role for the evolution of primitive organisms living at hydrothermal vents on the seafloor, Seewald adds. And elsewhere in the solar system, methane produced through the same process could provide an energy source for basic life forms.

See the full article here .

five-ways-keep-your-child-safe-school-shootings

Please help promote STEM in your local schools.

Stem Education Coalition

Woods Hole Oceanographic Institute

Vision & Mission

The ocean is a defining feature of our planet and crucial to life on Earth, yet it remains one of the planet’s last unexplored frontiers. For this reason, WHOI scientists and engineers are committed to understanding all facets of the ocean as well as its complex connections with Earth’s atmosphere, land, ice, seafloor, and life—including humanity. This is essential not only to advance knowledge about our planet, but also to ensure society’s long-term welfare and to help guide human stewardship of the environment. WHOI researchers are also dedicated to training future generations of ocean science leaders, to providing unbiased information that informs public policy and decision-making, and to expanding public awareness about the importance of the global ocean and its resources.
Mission Statement

The Woods Hole Oceanographic Institution is dedicated to advancing knowledge of the ocean and its connection with the Earth system through a sustained commitment to excellence in science, engineering, and education, and to the application of this knowledge to problems facing society.

#applied-research-technology, #cosmos, #earth-observation, #geology, #woods-hole-oceanographic-institution

From COSMOS Magazine: “Superdeep diamonds have a story to tell”

Cosmos Magazine bloc

16 August 2019
Richard A Lovett

1
Diamonds from the Juina area of Brazil. Most are superdeep diamonds. Credit Graham Pearson

Tiny imperfections in Brazilian diamonds have revealed a pocket of the Earth’s primordial past, deep in its interior.

In fact, scientists say, these rocks appear to have survived largely undisturbed for 4.5 billion years, making them older than the Moon or anything on the Earth’s surface.

Diamonds form naturally only under high-pressure conditions existing deep beneath the Earth’s crust. That makes them messengers from the mantle, which then rise toward the surface via volcanic conduits, where miners ultimately find them.

Most diamonds form at depths of 150 to 200 kilometres, says Suzette Timmerman, a Dutch geochemist who conducted her research at Australian National University. Diamonds from the Juina area of western Brazil are different, however.

“The Juina area is special because more than 99% of the diamonds form between 410 and 660 kilometres in depth,” she says.

That’s important, because diamonds are notoriously durable.

“Diamonds are the hardest, most indestructible natural substance known,” she says, “so they form a perfect window into the deep Earth.”

Timmerman’s study, published in the journal Science, focused on helium gas trapped in tiny bubbles of fluid in 23 of these diamonds.

Helium comes in two forms: helium-3 and helium-4. The early Solar System had a mix of the two determined by the composition of the interstellar gas cloud from which it formed. But helium-4 continues to be formed as a byproduct of certain types of radioactive decay, particularly the decay of heavy elements such as uranium and thorium.

“If we have a lot of helium-4, it means it must have had quite a bit of time to form,” Timmerman says. “If we find a lot of helium-3, this must be because it’s ancient.”

It’s not quite that simple, of course, because geological processes when the Earth was young tended to move uranium and thorium (and their subsequent production of helium-4) out of the mantle into upper-level rocks.

But when this is corrected for, Timmerman says, the helium isotope ratios in her diamonds prove that the helium trapped within them comes from regions very close in composition to the primordial matter from which the Earth initially formed – mantle rocks that, for whatever reason, never mixed with the rest of the mantle or with material descending from the crust.

“In order to get the compositions we see today,” she says, “it mustn’t have interacted with the rest of the mantle at least since the core and mantle separated” – something that probably occurred in the aftermath of the giant impact that formed the Moon. “It’s definitely a part of the Earth that hasn’t been interacting with the crust, basically since the beginning of time.”

How much of this primordial matter remains is unclear, she says, but one place it apparently does exist is beneath the diamond mines of Brazil. And, she notes, “with this work we are beginning to home in on what is probably the oldest remaining, comparatively undisturbed, material on Earth”.

Other scientists are impressed. “This is an interesting result, with a lot of potential to ‘map out’ elevated helium-3/helium-4 domains in the Erath’s deep interior,” says Matthew Jackson, a geochemist at the University of California, Santa Barbara who was not part of the study team.

It’s also intriguing because it comes only a year before the Japanese space agency hopes to return a sample of even more primordial material from asteroid 162173 Ryugu, and four years before NASA hopes to do the same for asteroid 101955 Bennu.

See the full article here .


five-ways-keep-your-child-safe-school-shootings
Please help promote STEM in your local schools.

Stem Education Coalition

#superdeep-diamonds-have-a-story-to-tell, #applied-research-technology, #if-we-have-a-lot-of-helium-4-it-means-it-must-have-had-quite-a-bit-of-time-to-form-if-we-find-a-lot-of-helium-3-this-must-be-because-its-ancient, #cosmos, #focusing-on-helium-gas-trapped-in-tiny-bubbles-of-fluid-in-23-of-these-diamonds, #geology, #helium-comes-in-two-forms-helium-3-and-helium-4

From COSMOS Magazine: “When it comes to volcanoes, Monte Carlo may save Naples”

Cosmos Magazine bloc

From COSMOS Magazine

01 August 2019
Barry Keily

Researchers combine stress and statistics to refine eruption risk.

1
Monte Nuovo is the vent of one of the smallest eruptions at Campi Flegrei, Italy. Credit Mauro Antonio Di Vito.

Contrary to cartoon depictions, volcanoes rarely erupt more than once from the same hole. In some cases, explosive ejections of magma, ash and rocks can kick off a substantial distance away from previous hotspots.

The ability to identify with any degree of precision likely eruption sites is a matter that has been the subject of intensive research for decades, but to date evidence has been substantially, and sometimes catastrophically, at odds with predictions.

Now, however, a team led by Eleonora Rivalta from the GFZ German Research Centre for Geosciences, in Potsdam, Germany, has come up with a new and promising approach that marries physics and mathematics.

Although the method has yet to be real-world tested, the researchers report that a retrospective comparison using eruptions that took place over centuries at Italy’s densely populated Campi Flegrei volcanic field, which includes the city of Naples, has shown encouraging results.

The problem of predicting exact eruption spots is at its keenest in the case of calderas – volcanoes on which the summit has collapsed, leaving craters that can be as big as 100 kilometres in diameter.

“Calderas have fed some of the most catastrophic eruptions on Earth and are extremely hazardous,” Rivalta and colleagues write in the journal Science Advances.

“However, their eruptions are generally few and far apart; thus, hazard is often underestimated by the local population, which, at some calderas, approaches one million.”

Predicting when and where eruptions could happen, the researchers add, is thus regarded as “extremely challenging”.

The difficulty arises because it is impossible to test the assumptions on which current models rest.

Hazard estimation proceeds from the not unreasonable idea that future eruptions are likely to occur in close proximity to the sites of past ones.

However, this presumes that the distribution of past volcanic vents indicates areas of geologic weakness. Such a presumption, the researchers write, is not supported by the evidence.

A second approach concedes an unknown mechanism determines the path which ascending magma takes but assumes there is a higher probability of a new vent opening near clusters of old ones than in somewhere unscarred.

This method is valid, Rivalta and colleagues confirm, inasmuch as the probabilities are borne out by the history of eruptions on Campi Flegrei, but because these events don’t happen very often, the number of available data points is insufficient to produce predictions with a useful degree of precision.

To overcome these issues, the researchers turned to the physics of magma flows, a field that has been comprehensively studied ever since Canadian geologist Reginal Aldworth Daly published the first research on it in the late nineteenth century.

They combined this with a statistical approach known as the Monte Carlo method, wherein calculations of events are run thousands of times in order to encompass the possible influence of unpredictable variables.

Monte Carlo simulations are widely used for risk analysis in fields as diverse as insurance, mining and finance.

Rivalta and colleagues based the limits of their calculations on existing data describing the stresses present, and already measured, across Campi Flegrei. The results showed that previous assumptions regarding the importance of existing faults in influencing magma flow were incorrect.

Faults certainly play a role, but it is less significant than assumed, and less direct – magma is likely to move at a tangent to them rather than mirror them.

Instead, the results showed that it was possible to predict the direction of magma flows as long as the stresses involved and the exact location of the subterranean magma chamber were known – matters that the researchers quickly concede are often “very poorly constrained”.

Nevertheless, they conclude, their method produces more accurate predictions – at least retrospectively – than existing ones.

“We show that magma trajectories, and thus eruptive vent locations, are so sensitive to stress variations that the previous vent locations at a volcano can be used to constrain the stress field to a sufficient degree of accuracy to render reliable physics-based vent forecasts possible,” they write.

See the full article here .


five-ways-keep-your-child-safe-school-shootings
Please help promote STEM in your local schools.

Stem Education Coalition

#when-it-comes-to-volcanoes-monte-carlo-may-save-naples, #applied-research-technology, #cosmos, #earth-observation, #geology, #monte-carlo-simulations, #vulcanology