Tag Archives: supervolcano

Volcano apocalypse – the 5 most notorious eruptions of all time

by Chris Phoenix Clarke

Volcanoes are pretty badass, let’s be honest.  In this particular blog I’ll be reviewing 5 of the most destructive natural events in Earth’s history, caused by 3 different volcanic mechanisms: stratovolcanoes, supervolcanoes and flood basalt eruptions.

The 'Volcano Man' G Brad Lewis photographed his friend standing in front of exploding lava at the edge of the Kilauea volcano in Hawaii.
The ‘Volcano Man’ G Brad Lewis photographed his friend standing in front of exploding lava at the edge of the Kilauea volcano in Hawaii.  Image credit: G Brad Lewis/Barcroft Media.

Everyone’s typical picture of a volcano is a tall, conic mountain with a crater at the top bellowing out ash and spewing out lava (a stratovolcano – see picture of Mount Fuji below).  Unfortunately, this is no more accurate than the stereotypical view that the English all drink tea and talk like the Queen, and Australians converse solely about barbecues and drink Fosters.  

There are many different types of volcano, ranging from the picture-postcard snow-crested peak of Mount Fuji in Japan (below) to the linear fissure vents of Iceland and Hawaii.  Some explode violently sending gas and dust high into the atmosphere, whereas some seep thick lava down gently-sloping flanks (known as shield volcanoes).  Others have enormous calderas — the area of a volcano that collapses in on itself and into the empty magma chamber following an eruption, leaving an incredibly vast, open, cauldron-like hole.  Volcanoes of this type and size are usually coined supervolcanoes, but are classified officially on their VEI rating — the Volcanic Explosivity Index — a logarithmic scale with each rise of 1 corresponding to a ten-fold increase in the amount of ejected material, with the highest rating being an 8; the lowest being a zero).

Mount Fuji is a stratovolcano that is also Japan's highest mountain, situated 100 km south of Tokyo. It last erupted in 1708.
Mount Fuji is a stratovolcano that is also Japan’s highest mountain, situated 100 km south of Tokyo. It last erupted in 1708.  Image credit: AFP/Getty Images.

Some volcanoes lie patiently dormant while others have died and gone to volcano heaven (or hell, shall we say) and are extinct.  Some volcanoes can even erupt for a million years and take centre stage in the largest mass extinction event our planet has ever known: the Permian-Triassic extinction event.  Said to have wiped out 90% of all living things, this catastrophe of 250 million years ago very nearly ended life on Earth before humans had even begun to evolve.

What follows are 5-of-the-best eruptions, so to speak, but one must remember that although fascinating, volcanoes are also furnaces of death and destruction and should be regarded equally with fear and caution as with curiosity and awe.

5) Mount Tambora, 10th April 1815.  Location: Sumbawa, Indonesia.  VEI rating: 7

Officially the largest eruption in recorded history, Mount Tambora is claimed to be the only VEI-7 in almost 2000 years.  It killed in excess of 70,000 people and caused 1816 to become known as the ‘year without a summer’ due to the effect it had on North American and European weather.  The lowering of global temperatures was such that crops failed and animals died, causing widespread starvation – the worst famine of the 19th century.

This volcanic winter, as it is known, is the reduction of global temperatures as a consequence of ash particles and sulphuric acid droplets physically blocking sunlight from reaching the surface of the Earth.

The eruption was heard over 2000 km away and the ejected material (ejecta) from the volcano measured over 160 km3 .

Mount Tambora is still active to this day, but almost reaching the 200th anniversary of the catastrophe it hasn’t shown any signs of exploding again with the same magnitude.

Aerial view of Mount Tambora. Image credit: Jialiang Gao (peace-on-earth.org).
Aerial view of Mount Tambora. Image credit: Jialiang Gao (peace-on-earth.org).

4) Yellowstone caldera, 2.1 – 0.64 million years ago.  Location:  [currently] Wyoming, United States.  VEI rating: 8

Like the pits of Hell portrayed in Dante’s Inferno, here lurks a reservoir of fire and brimstone in the heartland of the United States that has been responsible for many of the largest explosive volcanic eruptions in all of history.  I am, of course, talking about the now world-renowned Yellowstone hotspot.

90% of the planet’s volcanic activity is found at the boundaries between tectonic plates; the other 10% at hotspots.

Hotspots are areas of volcanic activity at seemingly random locations across the surface of the planet that are hypothesised to be caused by anomalously super-hot parts of the underlying mantle or particularly-thin sections of the Earth’s crust (or, indeed, both).

While the hotspots do themselves appear to drift very slowly (the mantle behaves like a highly-viscous liquid over geological time), the constant, and comparatively faster, movement of the tectonic plates which make up the crust move across the hotspots — tracing out a trail of volcanic structures above and away from them.  This is evident in island chains such as Hawaii and on land from the Yellowstone hotspot trail.  As the Pacific Plate has headed in a north-westerly direction over the last few tens-of-millions of years, the magma from the hotspot has intruded through the seafloor to build up volcanic islands that rise above sea level.

Once an island is formed it is very gradually dragged away from the hotspot by the tectonic plate until it is no longer positioned above the active area.  The process continues on and another island is made in its place — repeating again and again until an island chain starts to take shape.  The main island of Hawai’i is the newest (300,000 years old) and the oldest is the island of Kaua’i (4 million years old), but the chain actually stretches away from what is termed as the state of Hawaii all the way up to the Aleutian Trench near Russia — the eroded islands there being many tens-of-millions of years old.

On land, the Yellowstone hotspot has erupted nearly 20 times in the

The trail of calderas span several U.S. states as the North American tectonic plate moves across the hotspot. Image credit: Smithsonian National Museum of Natural History
The trail of calderas span several U.S. states as the North American tectonic plate moves across the hotspot. Image credit: Smithsonian National Museum of Natural History.

last 16.5 million years, with the trail of calderas originating at the Nevada-Oregon border, going right across Idaho and finishing at its current location at the most north-westerly tip of Wyoming — in Yellowstone National Park (if only Yogi Bear was made aware of the real nature of his surroundings!).  Fast-forward a little longer and a new caldera will undoubtedly form in Montana.

Inside the national park the Yellowstone Plateau consists of 3 calderas that date back to 2.1, 1.3 and 0.64 million years ago — the first and last of these being supereruptions, and the other a very sizeable VEI-7 (getting on twice the size of the Mount Tambora eruption of 1815).  The ejecta from the two supereruptions was approximately 2,500 km3 and over 1000 km3 , respectively, making the former the second largest VEI-8 eruption of all time.

3) Krakatoa, 26th August 1883.  Location:  Sunda Strait, Indonesia.  VEI rating: 6

A photograph of an Indonesian newspaper dated one month after the eruption, showing a drawing of Krakatoa as it was before the eruption of 1883.
A photograph of an Indonesian newspaper dated one month after the cataclysm of 1883, showing a drawing of Krakatoa as it was before the eruption.

The second, but unfortunately not last, entry on our list from the Indonesian archipelago, Krakatoa is largely regarded as the most notorious eruption in recorded history.  Having claimed the title as the loudest noise ever heard by human ears and creating the biggest tsunami wave ever seen with human eyes, it also has the rather more infamous statistic of killing approximately 120,000 people (figures of 36,000 made 130 years ago are alleged to have been grossly under-estimated) — a total that is probably the most number of human fatalities ever caused by a volcanic eruption.

Having only been a VEI-6 eruption, you might be wondering why Krakatoa was so devastating.  The truth is that no one really knows.  The favoured hypotheses suggest that some form of subsidence or landslide, either above ground or submarine, allowed the mixing of sea water with the volcano’s magma chamber causing a highly energetic phreatic explosion.  Either way, two thirds of the island disappeared overnight as a result of the cataclysm.

Such was the ferocity of the main explosion that sailors in the Sunda Strait had their ear drums shattered, and the noise could be heard as far away as Australia (over 3000 km away) — a distance that is comparable to travelling between London and Moscow!

The pressure wave caused barometers the world over to go crazy and reverberated around the world 7 times; the explosion having had the energy of 2 hundred million tonnes of TNT (or 200 megatonnes) making it 12,500 times more powerful than the bomb dropped on Hiroshima and 4 times as powerful as the largest nuclear device ever detonated (the Russian Tsar Bombe in 1950).

The great 9.0 Japanese earthquake of 2011 generated tsunami waves of 10 metres. Image credit: Mainichi Shimbun/Reuters
The great 9.0 Japanese earthquake of 2011 generated tsunami waves of 10 metres. Image credit: Mainichi Shimbun/Reuters.

But the two most deadly features of the Krakatoa explosion were the tsunamis and pyroclastic flows that followed.  A pyroclastic flow is a superheated, fast-moving cloud of noxious gas and dust that incinerates and suffocates as it propagates away from a volcano, sometimes for many tens, or even hundreds, of miles.  Indeed, the one generated by Krakatoa traversed 40 km of ocean on a cushion of heated air and inundated flabbergasted natives on the island of Sumatra, killing over 1000 people.

The tsunami surges reached their peak at 40 metres — some 3 to 4 times higher than the Boxing Day tsunami of 2001 and Japanese tsunami of 2011.  Tidal gauges registered increased levels as far away as the English Channel (although some scientists claim this was due to the globally circumnavigating pressure wave).  It was the sheer immensity of the flooding that caused over 90% of the deaths from the catastrophe.

Never before has humankind played witness to oceanic destruction on such a colossal scale.  The sight must have been truly terrifying.  It is therefore understandable that Krakatoa makes it into the top 3 eruptions of all time.

2) Lake Toba,  70,000 b.c.  Location:  Sumatra, Indonesia.  VEI rating: 8

The eruption at Lake Toba (also situated in Indonesia) is widely recognised as the largest volcanic event on Earth in the last 25 million years and the largest VEI-8 of all time.  Considered supervolcanic due to its VEI rating, the explosion ejected approximately 3000 km3 of material into the atmosphere, blanketing most of southern Asia in 15 cm of ash and causing a volcanic winter that lasted for nearly a decade.  Moreover, it is postulated that global temperatures didn’t recover fully for a further 1000 years (there is geological evidence in ice cores of dramatic and catastrophic climate change during this period).

Landsat image of Lake Toba. The caldera lake is 100 km long and 30 km wide. Image credit: NASA.
Landsat image of Lake Toba. The caldera lake is 100 km long and 30 km wide. Image credit: NASA.

But possibly the most extreme part of Lake Toba’s CV is the suggested ‘human bottleneck’ that ensued.  Homo sapiens were only just beginning to get itchy feet by considering to venture out of Africa at the time, and along with the other hominids (including the Neanderthals) it made for a pretty meagre world population.  The Earth was experiencing a glacial period (between 110,000 – 15,000 years ago) so technologies such as agriculture were far from being realised and to put it simply: humans hadn’t been around long enough to populate to anything resembling considerable numbers.

After the Toba catastrophe it is estimated that less than 10,000 humans remained on the planet.  Global temperatures — already low due to the glacial period — had dropped by 3-5 °C courtesy of the volcanic winter, and in doing so created more planetary ice cover, which in turn raised the Earth’s albedo (a measure of how reflective to sunlight a surface is) — further compounding the problem.  

It is any wonder we managed to survive at all and quite scary to think we very nearly faced extinction as a species.  For this reason Lake Toba makes it to number 2 on our list.

Lake Toba as it looks today.
Lake Toba as it looks today.

1) The Siberian Traps, 250 million years ago.  Location:  [what is now] Siberia, Russia.  VEI rating: n/a

The Permian-Triassic mass extinction (or ‘The Great Dying’ as it is commonly referred to) is the single largest extinction event since the emergence of multicellular life on Earth.

Wiping out 90% of all living things, The Great Dying has often been attributed to a gargantuan asteroid impact (far larger than the one responsible for the death of the dinosaurs) or a volcanic eruption of almost incomprehensible enormity and duration.

The 'Great Dying' -- or Permian-Triassic extinction event -- is the most deadly mass extinction of life in Earth's history.
The ‘Great Dying’ — or Permian-Triassic extinction event — is the most deadly mass extinction in Earth’s history.

It just so happens that an enormous volcanic event did occur around the same time, in what is now known as Siberia, Russia (the continents had very different geography hundreds of millions of years ago) — creating the Siberian Traps.  Covering an area of 2 million square kilometres (the size of Western Europe) the Traps are evidence of an eruption so massive that it spewed out up to 4 million km3 of lava!  The Earth literally split open in a number of different places and the magma inside bled out for — wait for it — one million years.  That’s one million years in case you didn’t hear me the first time.

The word ‘traps’ is derived from the Swedish trappa (meaning stairs) and is an example of a flood basalt.  This type of event is the massive eruption of lava over a wide area of land or ocean that creates huge plateaus and mountain ranges — often layered in composition and forming ridged edges that resemble stairs or steps (see below).

The Siberian Traps. Layers of flood basalt cover an area over 2 million square kilometres.
The Siberian Traps. Layers of flood basalt cover an area over 2 million square kilometres.

It’s unclear why this event took place; the best hypothesis supposes that a meteorite impact triggered the enormous splits to open, and is also backed by [literally] solid evidence.  A number of candidate craters have been discovered — the best situated in east Antarctica.  The crater is 500 km wide and is still intact, suggesting it was formed in the last few hundred million years.  It would have also been roughly antipodal to the placement of the Traps, meaning it is at the opposite location on the other side of the Earth.  The theory is controversial at best but some scientists hold that an impact on one side of a planet can affect its antipodal location — as if the force propagates along a straight line through the centre of the Earth connecting the two.  Either way, an impact of this size would doubtless trigger tectonic unrest the world over, causing massive volcanic activity.

Whether initiated by colossal asteroid or gaping fissures in the crust, or a combination of both, The Great Dying very nearly extinguished all life on Earth.  The flood basalt of the Siberian Traps is inextricably linked with the worst extinction event in history and is without doubt the most massive example of volcanic activity on the planet.  It is for this reason that it tops the list of the most notorious eruptions ever; a real volcano apocalypse — evident in the cold, icy plateaus of northern Russia.

 

 

Advertisements

5 roads to Armageddon?

by Chris Phoenix Clarke

Of all the bandwagons of all the ages it is perhaps fitting that the greatest one of all, is, according to its own proclamations, the very last bandwagon in the history of mankind. I am of course referring to ‘2012: Apocalypse Earth’.  You know, the one about the Mayan prophecy, the galactic alignment, judgement day etc.  The media, as you’d expect, are (somewhat ironically) having a field day with this doomsday scenario.  The end of the world, it seems, is a good earner.

Whether it be excruciatingly bad Hollywood blockbusters, sensationalist media reporting, or deluded religious types called Harold Camping, it appears that we all get enveloped in the dazzle and drama of doomsday prophecies one way or another.  Having said that, at the time of writing, interest in the subject has dwindled somewhat but I suspect as the year reaches its inevitable climax the interest will return with a reinvigorated vengeance.

It’s best then, that I try to set a few things straight and give you the chance to make up your own minds about the potential dangers we face. What follows are the most likely candidates, the basic scientific evidence behind them, and the probabilities of them becoming the global catastrophe that has been ‘prophesied’ to be.

Coronal Mass Ejections (CMEs)

Holding the award for the least badly-reported doomsday scenario, the Sun does actually seem to be Public Enemy #1 in 2012.  Like pre-menstrual stress, this is a time in the Sun’s life where it becomes irrationally agitated and angry in regular cycles; although unlike PMS (sadly) this occurs approximately every 11 years and is known as the solar maximum.  Contrary to popular belief, the imminent solar maximum actually reaches it peak in 2013 and not 2012.

As it reaches its maximum, the Sun plays host to increased levels of magnetic disturbance, which, simply put, is where its magnetic field lines become tangled and distorted and eventually snap, releasing billions of tonnes of highly-charged particles into space (this takes the form of a plasma containing mostly electrons and protons and is referred to as a CME).  Every so often the Earth is found in the cross-hairs; a fact that was made evident just 2 solar maximums ago in Quebec, Canada in 1989 where one of these stellar outbursts caused an entire blackout of the city.  This, though, was a mere flesh-wound compared with the one that hit us in 1859.  Scientists claim that had it happened in this day and age it would have knocked-out the entire grid of the Northern Hemisphere.  The Auroras (Northern lights) were even observed as far south as Cuba!

A CME as it erupts from the surface of the Sun

The danger a CME poses is its ability to inundate the Earth’s magnetosphere so intensely that it can no longer ‘keep its shields up’.  The magnetosphere–or Earth’s magnetic field–is tasked with protecting the planet from harmful particles, such as the solar wind, but due to the battering it receives at the hands of a CME its effectiveness is reduced and the harmful plasma filters through to the surface of the Earth.  This influx of charged particles knocks out electric grids; power lines melt and transformers explode thrusting vast areas of the planet into darkness.

But what a lot of people fail to realise is that no electricity = no ANYTHING.  Petrol stations can’t pump petrol, water cannot be pumped to houses… it would literally be anarchy in a matter of days and not weeks.  The real damage though is the recovery time, as there is simply not enough time or man-power to replace all the fried transformers in a quick and efficient manner.  Computer models even suggest it would take decades just to reach a fraction of the operating power we once had, if at all.

All this considered, the same computer models grimly announce that affected countries will suffer population death tolls of 50%, with the total reaching tens or even hundreds of millions.  It is certainly a bleak outlook.  The only saving grace is we would need to take a direct hit from a powerful CME for this to even pose a threat.

Chance of catastrophe happening in 2012: 1/10

Pole Reversal

A pole reversal  is just that: magnetic North and South switch orientation.  The Earth’s polarity changes.  Compasses point to the South.  This potential apocalyptic perpetrator also has sound scientific backing, with evidence in rocks on the ocean floor showing it has happened many times before.  As the tectonic plates which divide-up the Earth jostle for position, it is often the case that the crust pulls apart under the oceans at something called a divergent plate boundary.  This is where two plates move apart from each other causing the crust to tear and new magma to rise-up from deep within the Earth to fill the gap and solidify into rock.  As the process continues over time, the plates continue to separate further apart with this newer rock slowly becoming older rock on either side as new magma rises where this [now] older rock had done many thousands of years before.

Above: the process known as sea-floor spreading.                  Below: the magnetosphere before and during a reversal.

The key, though, is in the way the magma cools.  Magnetic minerals in the magma align towards the Earth’s magnetic field and harden in this pattern.  Upon examination of the ocean floor, scientists discovered a symmetrical pattern on either side of the plate boundary that showed parallel bands of rock alternating between magnetic north and magnetic south at regular intervals of time.  The implications were shocking:  The Earth’s magnetic field actually flips every few hundred thousand years or so, with the last reversal taking place 780,000 years ago and the current phase of magnetism actually being the longest sustained period of ‘non-flipping’ in the last 5 million years.

To say that we are overdue a geomagnetic reversal might be a gross understatement.  The reality, some say,  is that it has already begun.  Others argue that the rocks on the sea-floor show the existence of superchrons; periods of time where the polarity of the magnetic field remains the same for well over 10 million years at a time without reversing.  The most recent was the Cretaceous superchron 120 to 83 million years ago. Either way, one cannot ignore some of the most recent scientific research into magnetic anomalies.  I won’t go into detail, but the basic proof comes from satellite imagery showing areas of the magnetosphere where the field lines are already becoming distorted, and the real ominous news is that the size and frequency of the anomalies have increased in just the last 40 years alone.

The danger of a pole reversal is in its transition.  A complete reversal can take over 1000 years, during which the Earth’s magnetosphere effectively disappears and no longer acts as the protective shield blocking our planet from harmful solar radiation.  This leaves the Earth – and all life upon it – totally vulnerable.  It is not clear what effect this new found nakedness might have; some scientists claim that unless humans adapt to subterranean lifestyles, they will most certainly die from being burned.  This, and the fact that given time, the solar wind would strip Earth of it’s atmosphere – like it did on Mars millions of years ago – thus rendering the air unbreathable and as such, life impossible.  Also plant-life would die, causing food shortages for animals and humans alike, and those reliant on the Earth’s magnetic field lines for navigation would find themselves incredibly disorientated.

A bleak outlook indeed.

Thankfully there are also scientists who assure that there is absolutely no evidence of negative effects due to the omission of a magnetosphere.  Homo erectus (distant relatives of homo sapiens) seemed to manage just fine, and so did the various flora and fauna of the time.  If anything, they claim, the charged protons and electrons that make up the solar wind will actually create a substitute magnetosphere on contact with our atmosphere.

So the jury is still out on this one, and although it is a certainty that it will happen; there is absolutely no chance it will happen in the next few months.  If I had to hazard a guess it would be that the pole reversal – presuming it continues throwing-up anomalies at its current rate – would start to become evident in the next 100 years onwards.

Chance of catastrophe happening in 2012: 1/10,000

Supervolcanic Eruption

Supervolcanoes are enormous, but considering their immense size, few people are even aware of their existence.  And for the 25 or so that are currently known to science, Yellowstone is undoubtedly the most well-renowned, situated in Wyoming, USA (although most people would associate Yellowstone with being a national park and the home of Yogi Bear!).

The Mount Pinatubo eruption of 1991

To classify as a supervolcano, a volcano must be capable of producing an eruption that ejects more than 1,000 km3 of material.  To put this into perspective, the Eyjafjallajökull volcano which erupted in Iceland in 2010 – causing unprecedented aviation chaos over Europe – ejected the comparatively hiccup-sized amount of just 0.1 km3.

Supervolcanoes are the largest type of volcano, producing the largest eruptions and are therefore granted the highest rating on the Volcanic Explosivity Index (or VEI) as a VEI 8.  The Eyjafjallajökull eruption of 2010 was a VEI 4.  Other well known eruptions of recent memory are:  Mount St. Helens (1980) VEI 5, Vesuvius (79 AD) VEI 5, Mount Pinatubo (1991) VEI 6, and Krakatoa (1883) VEI 6.  Incidentally, the cataclysmic eruption of Krakatoa is considered to be the loudest noise ever heard by Man and the magnitude of the explosion was such that it caused global temperatures to drop by 1.2°C and darkened the sky for many years afterwards.  The official death toll was around 36,000 people, but proper estimates suggest that the figure was well in excess of 100,000.  One of the largest tsunami waves ever, measuring 45 metres high, inundated Indonesia as a consequence of the volcano literally blowing itself to bits (to put this into perspective also, the tsunami that hit Japan in 2011 was about 10-15 metres high).

And all this from a volcano of VEI 6.  All supervolcanoes are at least VEI 8.  In other words – in excess of one hundred times larger than Krakatoa!

Edvard Munch’s ‘The Scream’. The most valuable work of art ever to be sold at auction at $120 million. It is thought the sunset depicted was based on the incredible sunsets caused by the 1883 eruption of Krakatoa

If there is one piece of information that might put your mind at ease, it would be the fact that supervolcanoes run in what I call ‘geological time’.  This is to say that eruptions are so far apart that enough time passes for very boring things to happen to rocks.  Yellowstone, as an example, erupts on average every 600,000 years.  The entire history of human civilisation on the other hand, can easily fit into just 2 % of that time (10,000 years) with change to spare.  But without meaning to sound too reassuring, I should probably point out that Yellowstone last erupted over 640,000 years ago!

A supervolcanic eruption has the potential to kill millions of people in the vicinity of a few hundred miles from the volcano itself, and the immense ejection of dust and gases into the atmosphere would cause volcanic winters:  years where global temperatures plummet as a result of the obscuring of sunlight, and eventually a runaway-greenhouse-effect: the process by which the sudden increase in greenhouse gases released by the eruption cause global temperatures to rise.  Indeed, it is proposed that the supervolcanic eruption of Lake Toba, Indonesia in 71,500 BC was very nearly responsible for the eradication of the entire human race at the time.  Scientists believe only a couple of tens-of-thousands of humans survived the cataclysm.

This is a very genuine threat and it really is only a matter of [geological] time until it happens again.  Most supervolcanoes don’t show too much activity, but due to the fact that Yellowstone has a confirmed active – and very large – magma chamber beneath it, and quite regularly changes the lay of the landscape and has hundreds of small earthquakes, I’d say the risk is ‘imminent’.  The only redeeming factor is that warning signs should precede an eruption, and last for some time before the onset.

Chance of catastrophe happening in 2012: 1/100

Gamma-ray Burst (GRB)

The electromagnetic spectrum (if you paid attention in class) is the full-range of all the frequencies at which light propagates – or more accurately: the range of frequencies at which electromagnetic radiation travels – of which, visible light is but a small part of the range.  At the lower-frequency end you have radio waves and microwaves, and at the other, higher-frequency end, you have x-rays and gamma rays.  Frequency of electromagnetic radiation is calculated as the speed of light divided by the wavelength of the radiation.  This means that frequency is inversely proportional to wavelength; the larger the wavelength, the smaller the frequency.  This makes sense, as a shorter wavelength would repeat itself much more ‘frequently’ as it travels through the air than a longer wave, and thus, its frequency is higher.

That’s the science bit over and done with.

High frequency radiation, as the name implies, possesses high amounts of energy; and high energy can be very, very dangerous (as the year 1945 can attest to, if it were politically incorrect).  Gamma rays are the most energetic source of radiation in the Universe and it takes a very spectacular type of event to produce them in vast, concentrated outbursts.  Such events include, but are not restricted to,  the collision (and subsequent merger) of two neutron stars, or more commonly, in supernova and hypernova explosions.  I will concentrate on the latter.

Supernovae, and their ‘go large’ relatives, hypernovae, are the most violent events in existence.  Caused by the death-throws of a dying star, a supernova initiates after the gravitational collapse of the star’s core and obliterates itself in a wonderfully destructive explosion, the magnitude of which means it briefly outshines the entire galaxy it resides within.  But not all supernovae necessarily emit bursts of gamma radiation; it is thought only the most massive of stars do upon exploding.  Massive stars, after undergoing a supernova, usually form a neutron star from the leftovers: a city-sized, incredibly dense ball of matter, spinning unimaginably fast.  Neutron stars have so much mass squashed into such a small space that only one teaspoon of neutron star material would weigh 5000 billion kilograms!  That is the same as having 900 Great Pyramids of Giza stirred into your coffee!

But even more massive stars form what are undoubtedly the most sinister of all cosmic structures:  a black hole.   The leftovers of these supernovae are forced together so tightly that the sheer density of the material causes space and time to literally curve in on itself so much, that nothing entering can ever leave – not even light.

A black hole, spewing out gamma ray bursts from either pole

Both the creation of neutron stars and black holes from supernovae explosions are thought to be the catalyst for the production of GRBs.  The energy released in the processes take the form of jets shooting out straight from either pole, and although only brief – they can be quick flashes, or even bursts of a few minutes – the gamma rays explode-out over vast distances into the unsuspecting Universe.

If Earth was to be unfortunate enough to be in the way of a GRB in our own galaxy, the effects would be devastating.  The side of the Earth facing the burst would be dosed in lethal radiation, and everyone else on the planet would be faced with catastrophic damage to the atmosphere; resulting in an almost-definite mass extinction event.  Indeed, some scientists propose that the Ordovician mass extinction event of 450 million years ago could have been caused by a direct hit from a GRB.

Thankfully, in our own galaxy, a GRB occurs roughly every 100,000 years or so, and the percentage of those that might hit Earth is very low as you’d expect.

Chance of catastrophe happening in 2012: 1/100,000,000

Galactic alignment

The last of the potential doomsday candidates is the increase in gravity experienced by Earth as a result of the so-called ‘impending galactic alignment’.  This increase in gravity is alleged to cause the Earth to be effectively ‘stretched’ from either side, causing the tectonic plates that blanket the Earth to move violently against and away from each other.  The result would be an increase in earthquake frequency and magnitude, and trigger increased levels of volcanic activity – including new magmatic fissures (or tears in the Earth) – each with their own catastrophic side-effects such as tsunamis and volcanic winters.

The galactic alignment idea is, quite frankly, a load of inane and miss-informed sensationalist rubbish.  It is true that the Solar System does transverse the galactic plane every few tens-of-millions of years, but we currently reside several light years ‘above’ the galactic plane and won’t be transversing anything any time soon.  The idea that, from the Earth’s point-of-view, the Sun lines up with the galactic plane is pure nonsense and happens all the time anyhow.

I’m not too sure on the speculation, but I believe some claim that the combined pull of the supermassive black hole (Sagittarius A) at the centre of our galaxy and all the mass of stars along the plane would combine with the gravity of the Sun [as they line up] and cause the increased gravity I mentioned earlier.  Either that or the Earth lines-up in-between the Sun and Sagittarius A and gets stretched instead.  Some proponents of this idea even go so far as to suggest that each of the 5 mass-extinction events that have occurred on Earth have been down to the Solar System’s alignments with the galactic plane.  The problem is there is simply not enough mass, either in the plane, or indeed in the supermassive black hole itself, to cause any terrible gravitational effects on Earth.  The gravity caused by a given amount of mass is inversely proportional to its distance away, meaning something either has to be pretty close or pretty massive to have any effect, and even though Sagittarius A is pretty damn massive, it is simply too far away.  Even if you factor in the effects of dark matter (which I won’t indulge here), it still doesn’t add up.

The Milky Way face-on (left) and edge-on (right). The galactic plane is the horizontal line that passes through the entire galaxy when viewed from the side. The solar system is about 3/4 of the way from the centre, and quite a number of light years ‘above’ the centre line.

Chance of catastrophe happening in 2012: zero

The outlook

It seems the only road to disaster holding any apocalyptic weight is the Sun unleashing a direct CME.  The poles WILL reverse and the Earth WILL play host to a supervolcanic eruption, but there’s no reason to suspect it will happen in 2012.

My next blog deals with mass extinction events, and whether enough time will have elapsed for humans to be technologically-prepared enough before another one hits.  As I’ve stated, it is only a matter of time before something happens again to threaten the survival of humanity.  The question is: will we have had enough time to develop ways and methods to ensure the longevity of our species?  Will we have colonised space?  Will we have found ways to combat potential threats, such as large meteor impacts?

The Universe, it seems, plays dice with our potential survival, and time is the only thing that stands between us and mass extinction.

Do we have enough of it?…

written by Chris Phoenix Clarke