Posts
Climate change will shake the Earth
25
February, 2012
The
idea that a changing climate can persuade the ground to shake,
volcanoes to rumble and tsunamis to crash on to unsuspecting
coastlines seems, at first, to be bordering on the insane. How can
what happens in the thin envelope of gas that shrouds and protects
our world possibly influence the potentially Earth-shattering
processes that operate deep beneath the surface? The fact that it
does reflects a failure of our imagination and a limited
understanding of the manner in which the different physical
components of our planet – the atmosphere, the oceans, and the
solid Earth, or geosphere – intertwine and interact.
If
we think about climate change at all, most of us do so in a very
simplistic way: so, the weather might get a bit warmer; floods and
droughts may become more of a problem and sea levels will slowly
creep upwards. Evidence reveals, however, that our planet is an
almost unimaginably complicated beast, which reacts to a dramatically
changing climate in all manner of different ways; a few – like the
aforementioned – straightforward and predictable; some surprising
and others downright implausible. Into the latter category fall the
manifold responses of the geosphere.
The
world we inhabit has an outer rind that is extraordinarily sensitive
to change. While the Earth's crust may seem safe and secure, the
geological calamities that happen with alarming regularity confirm
that this is not the case. Here in the UK, we only have to go back a
couple years to April 2010, when the word on everyone's lips
was Eyjafjallajökull –
the ice-covered Icelandic volcano that brought UK and European air
traffic to a grinding halt. Less than a year ago, our planet's
ability to shock and awe headed the news once again as the east
coast of Japan was bludgeoned by
a cataclysmic combination of megaquake and tsunami, resulting – at
a quarter of a trillion dollars or so – in the biggest
natural-catastrophe bill ever.
In
the light of such events, it somehow seems appropriate to imagine the
Earth beneath our feet as a slumbering giant that tosses and turns
periodically in response to various pokes and prods. Mostly, these
are supplied by the stresses and strains associated with the eternal
dance of a dozen or so rocky tectonic plates across the face of our
world; a sedate waltz that proceeds at about the speed that
fingernails grow. Changes in the environment too, however, have a key
role to play in waking the giant, as growing numbers of geological
studies targeting our post-ice age world have disclosed.
Between
about 20,000 and 5,000 years ago, our planet underwent an astonishing
climatic transformation. Over the course of this period, it flipped
from the frigid wasteland of deepest and darkest ice age to the –
broadly speaking – balmy, temperate world upon which our
civilisation has developed and thrived. During this extraordinarily
dynamic episode, as the immense ice sheets melted and colossal
volumes of water were decanted back into the oceans, the pressures
acting on the solid Earth also underwent massive change. In response,
the crust bounced and bent, rocking our planet with a resurgence in
volcanic activity, a proliferation of seismic shocks and burgeoning
giant landslides.
The
most spectacular geological effects were reserved for high latitudes.
Here, the crust across much of northern Europe and North America had
been forced down by hundreds of metres and held at bay for tens of
thousands of years beneath the weight of sheets of ice 20 times
thicker than the height of the London Eye. As the ice dissipated in
soaring temperatures, the crust popped back up like a coiled spring
released, at the same time tearing open major faults and triggering
great earthquakes in places where they are unheard of today. Even
now, the crust underpinning those parts of Europe and North America
formerly imprisoned beneath the great continental ice sheets
continues to rise – albeit at a far more sedate rate.
As
last year's events in Japan most ably demonstrated, when the ground
shakes violently beneath the sea, a tsunami may not be far behind.
These unstoppable walls of water are hardly a surprise when they
happen within the so-called ring
of fire that
encompasses the Pacific basin but in the more tectonically benign
North Atlantic their manifestation could reasonably be regarded as a
bit of a shock. Nonetheless, there is plenty of good, hard evidence
that this was the case during post-glacial times. Trapped within the
thick layers of peat that pass for soil on Shetland – the UK's
northernmost outpost – are intrusions of sand that testify to the
inland penetration of three tsunamis during the last 10,000 years.
Volcanic
blasts too can be added to the portfolio of postglacial geological
pandemonium; the warming climate being greeted by an unprecedented
fiery outburst that wracked Iceland as its frozen carapace dwindled,
and against which the recent ashy ejaculation from the island's most
unpronounceable volcano pales.
The
huge environmental changes that accompanied the rapid post-glacial
warming of our world were not confined to the top and bottom of the
planet. All that meltwater had to go somewhere, and as the ice sheets
dwindled, so the oceans grew. An astounding 52m cubic kilometres of
water was sucked from the oceans to form the ice sheets, causing sea
levels to plummet by about 130 metres – the height of the Wembley
stadium arch. As the ice sheets melted so this gigantic volume of
water was returned, bending the crust around the margins of the ocean
basins under the enormous added weight, and provoking volcanoes in
the vicinity to erupt and faults to rupture, bringing geological
mayhem to regions remote from the ice's polar fastnesses.
The
breathtaking response of the geosphere as the great ice sheets
crumbled might be considered as providing little more than an
intriguing insight into the prehistoric workings of our world, were
it not for the fact that our planet is once again in the throes an
extraordinary climatic transformation – this time brought about by
human activities. Clearly, the Earth of the early 21st century bears
little resemblance to the frozen world of 20,000 years ago. Today,
there are no great continental ice sheets to dispose of, while the
ocean basins are already pretty much topped up. On the other hand,
climate change projections repeatedly support the thesis that global
average temperatures could rise at least as rapidly in the course of
the next century or so as during post-glacial times, reaching levels
at high latitudes capable of driving catastrophic breakup of polar
ice sheets as thick as those that once covered much of Europe and
North America. Could it be then, that if we continue to allow
greenhouse gas emissions to rise unchecked and fuel serious warming,
our planet's crust will begin to toss and turn once again?
The
signs are that this is already happening. In the detached US state of
Alaska, where climate change has propelled temperatures upwards by
more than 3C in the last half century, the glaciers are melting at a
staggering rate, some losing up to 1km in thickness in the last 100
years. The reduction in weight on the crust beneath is allowing
faults contained therein to slide more easily, promoting increased
earthquake activity in recent decades. The permafrost that helps hold
the state's mountain peaks together is also thawing rapidly, leading
to a rise in the number of giant rock and ice avalanches. In fact, in
mountainous areas around the world, landslide activity is on the up;
a reaction both to a general ramping-up of global temperatures and to
the increasingly frequent summer heatwaves.
Whether
or not Alaska proves to be the "canary in the cage" – the
geological shenanigans there heralding far worse to come – depends
largely upon the degree to which we are successful in reducing the
ballooning greenhouse gas burden arising from our civilisation's
increasingly polluting activities, thereby keeping rising global
temperatures to a couple of degrees centigrade at most. So far, it
has to be said, there is little cause for optimism, emissions
rocketing by almost 6% in 2010 when
the world economy continued to bump along the bottom. Furthermore,
the failure to make any real progress on emissions control at last
December's Durban climate conference ensures
that the outlook is bleak. Our response to accelerating climate
change continues to be consistently asymmetric, in the sense that it
is far below the level that the science says is needed if we are to
have any chance of avoiding the all-pervasive devastating
consequences.
So
what – geologically speaking – can we look forward to if we
continue to pump out greenhouse gases at the current hell-for-leather
rate? With resulting global average temperatures likely to be several
degrees higher by this century's end, we could almost certainly say
an eventual goodbye to the Greenland ice sheet, and probably that
covering West Antarctica too, committing us – ultimately – to a
10-metre or more hike in sea levels.
GPS
measurements reveal that the crust beneath the Greenland ice sheet is
already rebounding in response to rapid melting, providing the
potential – according to researchers – for future earthquakes, as
faults beneath the ice are relieved of their confining load. The
possibility exists that these could trigger submarine landslides
spawning tsunamis capable of threatening North Atlantic coastlines.
Eastern Iceland is bouncing back too as its Vatnajökull ice
cap fades away. When and if it vanishes entirely, new research
predicts a lively response from the volcanoes currently residing
beneath. A dramatic elevation in landslide activity would be
inevitable in the Andes, Himalayas, European Alps and elsewhere, as
the ice and permafrost that sustains many mountain faces melts and
thaws.
Across
the world, as sea levels climb remorselessly, the load-related
bending of the crust around the margins of the ocean basins might –
in time – act to sufficiently "unclamp" coastal faults
such as California's San Andreas, allowing them to move more easily;
at the same time acting to squeeze magma out of susceptible volcanoes
that are primed and ready to blow.
The
bottom line is that through our climate-changing activities we are
loading the dice in favour of escalating geological havoc at a time
when we can most do without it. Unless there is a dramatic and
completely unexpected turnaround in the way in which the human race
manages itself and the planet, then long-term prospects for our
civilisation look increasingly grim. At a time when an additional
220,000 people are lining up at the global soup kitchen each and
every night; when energy, water and food resources are coming under
ever-growing pressure, and when the debilitating effects of
anthropogenic climate change are insinuating themselves increasingly
into every nook and cranny of our world and our lives, the last thing
we need is for the dozing subterranean giant to awaken.
Bill
McGuire is
professor of geophysical and climate hazards at University College
London. Waking the Giant: How a Changing Climate Triggers
Earthquakes, Tsunamis and Volcanoes is published by Oxford University
Press.
25
February, 2012
The
idea that a changing climate can persuade the ground to shake,
volcanoes to rumble and tsunamis to crash on to unsuspecting
coastlines seems, at first, to be bordering on the insane. How can
what happens in the thin envelope of gas that shrouds and protects
our world possibly influence the potentially Earth-shattering
processes that operate deep beneath the surface? The fact that it
does reflects a failure of our imagination and a limited
understanding of the manner in which the different physical
components of our planet – the atmosphere, the oceans, and the
solid Earth, or geosphere – intertwine and interact.
If
we think about climate change at all, most of us do so in a very
simplistic way: so, the weather might get a bit warmer; floods and
droughts may become more of a problem and sea levels will slowly
creep upwards. Evidence reveals, however, that our planet is an
almost unimaginably complicated beast, which reacts to a dramatically
changing climate in all manner of different ways; a few – like the
aforementioned – straightforward and predictable; some surprising
and others downright implausible. Into the latter category fall the
manifold responses of the geosphere.
The
world we inhabit has an outer rind that is extraordinarily sensitive
to change. While the Earth's crust may seem safe and secure, the
geological calamities that happen with alarming regularity confirm
that this is not the case. Here in the UK, we only have to go back a
couple years to April 2010, when the word on everyone's lips
was Eyjafjallajökull –
the ice-covered Icelandic volcano that brought UK and European air
traffic to a grinding halt. Less than a year ago, our planet's
ability to shock and awe headed the news once again as the east
coast of Japan was bludgeoned by
a cataclysmic combination of megaquake and tsunami, resulting – at
a quarter of a trillion dollars or so – in the biggest
natural-catastrophe bill ever.
In
the light of such events, it somehow seems appropriate to imagine the
Earth beneath our feet as a slumbering giant that tosses and turns
periodically in response to various pokes and prods. Mostly, these
are supplied by the stresses and strains associated with the eternal
dance of a dozen or so rocky tectonic plates across the face of our
world; a sedate waltz that proceeds at about the speed that
fingernails grow. Changes in the environment too, however, have a key
role to play in waking the giant, as growing numbers of geological
studies targeting our post-ice age world have disclosed.
Between
about 20,000 and 5,000 years ago, our planet underwent an astonishing
climatic transformation. Over the course of this period, it flipped
from the frigid wasteland of deepest and darkest ice age to the –
broadly speaking – balmy, temperate world upon which our
civilisation has developed and thrived. During this extraordinarily
dynamic episode, as the immense ice sheets melted and colossal
volumes of water were decanted back into the oceans, the pressures
acting on the solid Earth also underwent massive change. In response,
the crust bounced and bent, rocking our planet with a resurgence in
volcanic activity, a proliferation of seismic shocks and burgeoning
giant landslides.
As
last year's events in Japan most ably demonstrated, when the ground
shakes violently beneath the sea, a tsunami may not be far behind.
These unstoppable walls of water are hardly a surprise when they
happen within the so-called ring
of fire that
encompasses the Pacific basin but in the more tectonically benign
North Atlantic their manifestation could reasonably be regarded as a
bit of a shock. Nonetheless, there is plenty of good, hard evidence
that this was the case during post-glacial times. Trapped within the
thick layers of peat that pass for soil on Shetland – the UK's
northernmost outpost – are intrusions of sand that testify to the
inland penetration of three tsunamis during the last 10,000 years.
Volcanic
blasts too can be added to the portfolio of postglacial geological
pandemonium; the warming climate being greeted by an unprecedented
fiery outburst that wracked Iceland as its frozen carapace dwindled,
and against which the recent ashy ejaculation from the island's most
unpronounceable volcano pales.
The
huge environmental changes that accompanied the rapid post-glacial
warming of our world were not confined to the top and bottom of the
planet. All that meltwater had to go somewhere, and as the ice sheets
dwindled, so the oceans grew. An astounding 52m cubic kilometres of
water was sucked from the oceans to form the ice sheets, causing sea
levels to plummet by about 130 metres – the height of the Wembley
stadium arch. As the ice sheets melted so this gigantic volume of
water was returned, bending the crust around the margins of the ocean
basins under the enormous added weight, and provoking volcanoes in
the vicinity to erupt and faults to rupture, bringing geological
mayhem to regions remote from the ice's polar fastnesses.
The
breathtaking response of the geosphere as the great ice sheets
crumbled might be considered as providing little more than an
intriguing insight into the prehistoric workings of our world, were
it not for the fact that our planet is once again in the throes an
extraordinary climatic transformation – this time brought about by
human activities. Clearly, the Earth of the early 21st century bears
little resemblance to the frozen world of 20,000 years ago. Today,
there are no great continental ice sheets to dispose of, while the
ocean basins are already pretty much topped up. On the other hand,
climate change projections repeatedly support the thesis that global
average temperatures could rise at least as rapidly in the course of
the next century or so as during post-glacial times, reaching levels
at high latitudes capable of driving catastrophic breakup of polar
ice sheets as thick as those that once covered much of Europe and
North America. Could it be then, that if we continue to allow
greenhouse gas emissions to rise unchecked and fuel serious warming,
our planet's crust will begin to toss and turn once again?
The
signs are that this is already happening. In the detached US state of
Alaska, where climate change has propelled temperatures upwards by
more than 3C in the last half century, the glaciers are melting at a
staggering rate, some losing up to 1km in thickness in the last 100
years. The reduction in weight on the crust beneath is allowing
faults contained therein to slide more easily, promoting increased
earthquake activity in recent decades. The permafrost that helps hold
the state's mountain peaks together is also thawing rapidly, leading
to a rise in the number of giant rock and ice avalanches. In fact, in
mountainous areas around the world, landslide activity is on the up;
a reaction both to a general ramping-up of global temperatures and to
the increasingly frequent summer heatwaves.
Whether
or not Alaska proves to be the "canary in the cage" – the
geological shenanigans there heralding far worse to come – depends
largely upon the degree to which we are successful in reducing the
ballooning greenhouse gas burden arising from our civilisation's
increasingly polluting activities, thereby keeping rising global
temperatures to a couple of degrees centigrade at most. So far, it
has to be said, there is little cause for optimism, emissions
rocketing by almost 6% in 2010 when
the world economy continued to bump along the bottom. Furthermore,
the failure to make any real progress on emissions control at last
December's Durban climate conference ensures
that the outlook is bleak. Our response to accelerating climate
change continues to be consistently asymmetric, in the sense that it
is far below the level that the science says is needed if we are to
have any chance of avoiding the all-pervasive devastating
consequences.
So
what – geologically speaking – can we look forward to if we
continue to pump out greenhouse gases at the current hell-for-leather
rate? With resulting global average temperatures likely to be several
degrees higher by this century's end, we could almost certainly say
an eventual goodbye to the Greenland ice sheet, and probably that
covering West Antarctica too, committing us – ultimately – to a
10-metre or more hike in sea levels.
GPS
measurements reveal that the crust beneath the Greenland ice sheet is
already rebounding in response to rapid melting, providing the
potential – according to researchers – for future earthquakes, as
faults beneath the ice are relieved of their confining load. The
possibility exists that these could trigger submarine landslides
spawning tsunamis capable of threatening North Atlantic coastlines.
Eastern Iceland is bouncing back too as its Vatnajökull ice
cap fades away. When and if it vanishes entirely, new research
predicts a lively response from the volcanoes currently residing
beneath. A dramatic elevation in landslide activity would be
inevitable in the Andes, Himalayas, European Alps and elsewhere, as
the ice and permafrost that sustains many mountain faces melts and
thaws.
Across
the world, as sea levels climb remorselessly, the load-related
bending of the crust around the margins of the ocean basins might –
in time – act to sufficiently "unclamp" coastal faults
such as California's San Andreas, allowing them to move more easily;
at the same time acting to squeeze magma out of susceptible volcanoes
that are primed and ready to blow.
The
bottom line is that through our climate-changing activities we are
loading the dice in favour of escalating geological havoc at a time
when we can most do without it. Unless there is a dramatic and
completely unexpected turnaround in the way in which the human race
manages itself and the planet, then long-term prospects for our
civilisation look increasingly grim. At a time when an additional
220,000 people are lining up at the global soup kitchen each and
every night; when energy, water and food resources are coming under
ever-growing pressure, and when the debilitating effects of
anthropogenic climate change are insinuating themselves increasingly
into every nook and cranny of our world and our lives, the last thing
we need is for the dozing subterranean giant to awaken.
Bill
McGuire is
professor of geophysical and climate hazards at University College
London. Waking the Giant: How a Changing Climate Triggers
Earthquakes, Tsunamis and Volcanoes is published by Oxford University
Press.
More Fatal Earthquakes to Come, Geologists Warn
"Climate
change may play a critical role in triggering certain faults in
certain places where they could kill a hell of a lot of people,”
says Professor McGuire. Some of his colleagues suspect the process
may already have started.
Here, both Guy McPherson and Paul Beckworth talk about the connections between earthquakes and climate change in the context of the recent quake in Nepal
Rumbling
from ocean
trenches could be sign that Japan faces mega earthquake
"Climate
change may play a critical role in triggering certain faults in
certain places where they could kill a hell of a lot of people,”
says Professor McGuire. Some of his colleagues suspect the process
may already have started.
Here, both Guy McPherson and Paul Beckworth talk about the connections between earthquakes and climate change in the context of the recent quake in Nepal
trenches could be sign that Japan faces mega earthquake
11
May, 2015
Researchers
in Japan have for the first time
detected
and traced shallow tremors under
the ocean that could be a sign that the country is heading towards a
huge earthquake. But the technique itself may one day help us predict
exactly when such an event would take place, which could save
thousands of lives.
Japan
still has the devastating 9.0 magnitude, megathrust earthquake in
Tohoku in fresh memory, which produced a powerful tsunami and killed
nearly 16,000 people when
it hit in 2011. It is therefore no wonder that Japanese researchers
are the first to detect weak signals of seismic activity.
Japan
already has the most powerful seismic network in the world – and
research institutions in the country are constantly growing it. Ocean
Bottom Seismometers, which measure motion under the sea, have greatly
facilitated these efforts by listening to the “rumbling” that is
created when two
tectonic plates meet.
Such instruments have helped detect low-energy, “slow
earthquakes”
along oceanic trenches that we otherwise wouldn’t notice.
These
earthquakes, which we
know are produced deep
under the famous San Andreas fault, preceded
the Tohoku Earthquake.
They occur much more slowly than standard earthquakes. If they are
associated with the underground movement of magma and hot water but
they are not related to volcanoes, they are knows as “non-volcanic
tremors”.
By comparison, big earthquakes are caused by the rupture of faults
and give rise to short-lived, high-energy seismic waves.
Slow-slip
earthquakes and tremors don’t cause any damage on their own.
However, if they coincide with very-low-frequency earthquakes they
can. These are another type of slow earthquake that is caused by
processes deeper down under ground than tremors and usually indicate
fault motions near the dangerous area where the tectonic plates meet.
If all these types of slow earthquakes take place, along the faulted
zone at different depths, they could be a sign we are near to a
mega-thrust earthquake.
The
researchers – who investigated the Kyushu
Palau Ridge,
southeast of Kyushu – have, for the first time, been able to detect
and map shallow tremors in correlation with the other kinds of slow
earthquakes. Even more importantly, they have showed what direction
all these events are moving in. This kind of detailed knowledge of
seismic activity is considered one of the most reliable ways of
predicting big earthquakes.
Warning signs
What
the study found out is that the waves produced by all these quiet
earthquakes consistently migrated north along the ridge. The movement
abruptly ended at the limit of the trench, where it was blocked by a
so-called locked
zone –
where friction keeps the two plates together so they can’t slip –
where previous mega-thrust events have occurred. After this, the
waves travelled east.
This
does not look promising, as to avoid a mega-thrust earthquake you’d
prefer the slow quakes to stay in a locked zone, where the stress
caused by them can be released and the movement can fizzle out. In
this case, however, they are probably causing the coupling between
the two plates to weaken, which is expected before a mega-thrust
event.
The
study, which was published in Science on May 7, shows that shallow
slow earthquakes may therefore become a reliable way of detecting
when and where the next mega earthquake will strike. This can be done
by deploying ocean bottom seismometers along different trenches. In
that way, we could detect the pattern of earthquakes in various
places so that they would become an exact marker of when any
mega-thrust earthquake strikes under the ocean, often causing a
tsunami as well.
"
The
next such earthquake could strike the coast of Kyushu, a region well
known for its dangerous volcanoes. Let’s hope that, by then, we
have come far enough to prevent the same devastation as we saw in
2011. No place is better than Japan to drive such technological
progress.
5/08/2015
-- 11 Large volcanic eruptions in 1 day! Sakurajima Volcano in Japan
Dutchsinse
May
8, 2015 - 11 separate large blasts occurred at Sakurajima Volcano on
mainland South Japan in just one days time.
Over 30 minutes of eruptions compiled from the day. 7 daytime eruptions, and 4 eruptions after dark. Then the feed was CUT by the Japanese webcam host!
This is like 2011 all over again, multiple large eruptions at Sakurajima means pressure is building in the region. Sakurajima is like a pressure gauge on the Pacific plate, when we see Sakurajima show major activity, we can expect large earthquake activity to follow in nearby adjacent areas just to the North and just to the South of this location in Japan.
These 11 eruptions were recorded via video capture from the streaming webcams provided by the University of Tokyo, and the JSA.
You can watch (record) your own videos of this volcano using the webcams on http://www.volcanodiscovery.com
This new volcanic activity comes on the heels of multiple large earthquakes in the West Pacific, the announcement that a dormant volcano near Tokyo (silent for 800 years) is coming to life, and with a new Eruption in the Philippines.
All this happened after deep movement in the Asthenosphere below the West Pacific.
Studies (and tests in the field) have been done which prove Asthenosphere movement (deep below the plate) causes shallow movement upon the plate above.
When the deep movement occurs, it displaces a larger region above the epicenter, the magma chambers located between the Asthenosphere, and the crust are also displaced, which then produces earthquake + volcano activity.
See more on the deep asthenosphere findings here:
http://phys.org/news/2015-02-north-am...
Over 30 minutes of eruptions compiled from the day. 7 daytime eruptions, and 4 eruptions after dark. Then the feed was CUT by the Japanese webcam host!
This is like 2011 all over again, multiple large eruptions at Sakurajima means pressure is building in the region. Sakurajima is like a pressure gauge on the Pacific plate, when we see Sakurajima show major activity, we can expect large earthquake activity to follow in nearby adjacent areas just to the North and just to the South of this location in Japan.
These 11 eruptions were recorded via video capture from the streaming webcams provided by the University of Tokyo, and the JSA.
You can watch (record) your own videos of this volcano using the webcams on http://www.volcanodiscovery.com
This new volcanic activity comes on the heels of multiple large earthquakes in the West Pacific, the announcement that a dormant volcano near Tokyo (silent for 800 years) is coming to life, and with a new Eruption in the Philippines.
All this happened after deep movement in the Asthenosphere below the West Pacific.
Studies (and tests in the field) have been done which prove Asthenosphere movement (deep below the plate) causes shallow movement upon the plate above.
When the deep movement occurs, it displaces a larger region above the epicenter, the magma chambers located between the Asthenosphere, and the crust are also displaced, which then produces earthquake + volcano activity.
See more on the deep asthenosphere findings here:
http://phys.org/news/2015-02-north-am...
Expert warns Japan has entered ‘era of great quakes and eruptions’ – volcanoes stirring across Japan
Nicaragua’s Telica Volcano dusts town with ash – 30 eruptions reported after 8 year hiatus
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