Tag Archives: Earthquakes

Wilder shores of science yield new ideas on climate

New ideas on climate mean earthquake scientists know more about global heating and astronomers worry over rising warmth.

LONDON, 22 September, 2020 – Science has extended research into the global heating crisis, thanks to new ideas on climate. And, conversely, climate change has extended science in unexpected ways.

Seismologists believe they may have a new way to take the temperature of the world’s oceans. And astronomers focused on distant galaxies have unwittingly amassed a 30-year record of climate change in the Earth’s own atmosphere.

Both discoveries, in the same week, start with the simple physics of sight and sound. US and Chinese researchers report in the journal Science that records from submarine earthquakes could now deliver an unexpected way of measuring the warmth of the water.

Submarine earthquakes create a pattern of sound that can be transmitted immense distances through the ocean without much weakening. And, since the speed of sound in water increases as the temperature of the water rises, the length of time the sound takes to reach detector equipment is itself an indicator of ocean temperature.

Seismologists know – from waves travelling through the Earth’s crust and its deep interior – when and where the earthquakes happen. Seismic waves sprint through rock at rates measured in kilometres per second. Sound waves propagate through oceans at rates measured in kilometres per hour.

“It is of prime importance that astronomy uses its unique perspective to claim this simple fact: there is no planet B”

Just as the differences between the speed of lightning and the speed of thunder can establish the distance of an electrical storm, so if researchers know the time and distance of the sea floor event, they have a way of taking the temperature of the water. The constant rumbling of a living planet could offer a new set of easily assembled readings.

“The key is that we use repeating earthquakes – earthquakes that happen again and again in the same place,” said Wenbo Wu, of the California Institute of Technology, who led the Science study.

“We’re looking at earthquakes that occur off Sumatra in Indonesia, and we measure when they arrive in the central Indian Ocean. It takes about half an hour for them to travel that distance, with water temperature causing about one tenth of a second difference. It’s a very small fractional change, but we can measure it.”

The finding matters because – although humans have been recording local ground and air temperatures for at least 300 years, and worldwide for more than a century – it is much harder to be sure about ocean temperatures: the seas cover 70% of the planet, to an average depth of more than 3 kms, and the temperatures vary with both depth and latitude.

Sound goes deep

Oceanographic research is costly, technically challenging, and uneven. Researchers know that the oceans are responding to climate change driven by global heating as a consequence of greenhouse gas emissions: they do not, however, yet have an assured measure of how much heat the oceans have absorbed, and will go on absorbing.

“The ocean plays a role in the rate that the climate is changing,” said Jörn Callies of Caltech, a co-author. “The ocean is the main reservoir of energy in the climate system, and the deep ocean in particular is important to monitor. One advantage of our method is that the sound waves sample depths below 2,000 metres where there are very few conventional measurements.”

Paradoxically, astronomers need to know a great deal about the first few thousand metres of planet Earth as they peer into the furthest reaches of the universe: what they see and how well they see it is affected by atmospheric temperature, turbulence and moisture.

As ground-based telescopes become bigger and more sensitive – the Extremely Large Telescope now under construction at Paranal in northern Chile will collect light with a mirror 39 metres across – so do the challenges of eliminating the atmospheric turbulence that puts the twinkle in the stars of the night sky: cold air and warm air refract light differently, to create a blur. The bigger the telescope, the greater will be the problem of blur.

For three decades, scientists in the highest and driest part of Chile have been recording subtle and not so subtle atmospheric change. And according to the journal Nature Astronomy, climate change is already beginning to affect astronomical research, and will go on creating problems.

Terrestrial disturbances

“The data showed a 1.5°C increase in near-ground temperature over the last four decades at the Paranal Observatory,” said Susanne Crewell of the University of Cologne. “This is slightly higher than the worldwide average of 1°C since the pre-industrial age.”

Average wind speeds – wind also affects the precision of observations – have increased by 3 or 4 metres per second in the same period. Humidity, too, is expected to change as the world moves to what could be a 4°C average rise in temperature by the century’s end.

The message is that conditions on Earth can disturb the observations and mask the understanding of events billions of light years away and billions of years ago. Astronomers, too, need to sound the alarm about climate change, she and her colleagues write.

“To do so, a massive cultural shift is needed,” they conclude, “and it is of prime importance that astronomy uses its unique perspective to claim this simple fact: there is no planet B.” – Climate News Network

New ideas on climate mean earthquake scientists know more about global heating and astronomers worry over rising warmth.

LONDON, 22 September, 2020 – Science has extended research into the global heating crisis, thanks to new ideas on climate. And, conversely, climate change has extended science in unexpected ways.

Seismologists believe they may have a new way to take the temperature of the world’s oceans. And astronomers focused on distant galaxies have unwittingly amassed a 30-year record of climate change in the Earth’s own atmosphere.

Both discoveries, in the same week, start with the simple physics of sight and sound. US and Chinese researchers report in the journal Science that records from submarine earthquakes could now deliver an unexpected way of measuring the warmth of the water.

Submarine earthquakes create a pattern of sound that can be transmitted immense distances through the ocean without much weakening. And, since the speed of sound in water increases as the temperature of the water rises, the length of time the sound takes to reach detector equipment is itself an indicator of ocean temperature.

Seismologists know – from waves travelling through the Earth’s crust and its deep interior – when and where the earthquakes happen. Seismic waves sprint through rock at rates measured in kilometres per second. Sound waves propagate through oceans at rates measured in kilometres per hour.

“It is of prime importance that astronomy uses its unique perspective to claim this simple fact: there is no planet B”

Just as the differences between the speed of lightning and the speed of thunder can establish the distance of an electrical storm, so if researchers know the time and distance of the sea floor event, they have a way of taking the temperature of the water. The constant rumbling of a living planet could offer a new set of easily assembled readings.

“The key is that we use repeating earthquakes – earthquakes that happen again and again in the same place,” said Wenbo Wu, of the California Institute of Technology, who led the Science study.

“We’re looking at earthquakes that occur off Sumatra in Indonesia, and we measure when they arrive in the central Indian Ocean. It takes about half an hour for them to travel that distance, with water temperature causing about one tenth of a second difference. It’s a very small fractional change, but we can measure it.”

The finding matters because – although humans have been recording local ground and air temperatures for at least 300 years, and worldwide for more than a century – it is much harder to be sure about ocean temperatures: the seas cover 70% of the planet, to an average depth of more than 3 kms, and the temperatures vary with both depth and latitude.

Sound goes deep

Oceanographic research is costly, technically challenging, and uneven. Researchers know that the oceans are responding to climate change driven by global heating as a consequence of greenhouse gas emissions: they do not, however, yet have an assured measure of how much heat the oceans have absorbed, and will go on absorbing.

“The ocean plays a role in the rate that the climate is changing,” said Jörn Callies of Caltech, a co-author. “The ocean is the main reservoir of energy in the climate system, and the deep ocean in particular is important to monitor. One advantage of our method is that the sound waves sample depths below 2,000 metres where there are very few conventional measurements.”

Paradoxically, astronomers need to know a great deal about the first few thousand metres of planet Earth as they peer into the furthest reaches of the universe: what they see and how well they see it is affected by atmospheric temperature, turbulence and moisture.

As ground-based telescopes become bigger and more sensitive – the Extremely Large Telescope now under construction at Paranal in northern Chile will collect light with a mirror 39 metres across – so do the challenges of eliminating the atmospheric turbulence that puts the twinkle in the stars of the night sky: cold air and warm air refract light differently, to create a blur. The bigger the telescope, the greater will be the problem of blur.

For three decades, scientists in the highest and driest part of Chile have been recording subtle and not so subtle atmospheric change. And according to the journal Nature Astronomy, climate change is already beginning to affect astronomical research, and will go on creating problems.

Terrestrial disturbances

“The data showed a 1.5°C increase in near-ground temperature over the last four decades at the Paranal Observatory,” said Susanne Crewell of the University of Cologne. “This is slightly higher than the worldwide average of 1°C since the pre-industrial age.”

Average wind speeds – wind also affects the precision of observations – have increased by 3 or 4 metres per second in the same period. Humidity, too, is expected to change as the world moves to what could be a 4°C average rise in temperature by the century’s end.

The message is that conditions on Earth can disturb the observations and mask the understanding of events billions of light years away and billions of years ago. Astronomers, too, need to sound the alarm about climate change, she and her colleagues write.

“To do so, a massive cultural shift is needed,” they conclude, “and it is of prime importance that astronomy uses its unique perspective to claim this simple fact: there is no planet B.” – Climate News Network

Earthquakes 'may add to methane leaks'

FOR IMMEDIATE RELEASE
Methane is a potent greenhouse gas which in the short term is a much greater threat to global temperatures than carbon dioxide. Now researchers think it can be released by earthquakes.

LONDON, 31 July – And here’s another shuddering twist to the horror story that is climate change: even earthquakes may play a role. Large quantities of methane may have escaped during a violent earthquake that shook the floor of the Arabian Sea in 1945, according to German and Swiss researchers.

David Fischer of the University of Bremen and colleagues from the Alfred Wegener Institute in Bremerhaven and the ETH in Zurich explored the region in a research ship in 2007, and began to examine cores of sediment from the seabed.

One core, from just 1.6 metres below the seabed, contained methane hydrate – an ice-like mixture of methane and water –  and the other did not. But, the researchers report in Nature Geoscience, both cores carried subtle chemical evidence that at some point in the past dramatic quantities of methane or natural gas had actually flowed through the sediments beneath the Arabian Sea.

Since the methane would move as a gas, there is only one direction it could go: bubbling upwards through the sea into the atmosphere. And since methane is a potent greenhouse gas – at least 23 times more potent than carbon dioxide – such escapes could be significant.

“We started going through the literature and found that a major earthquake had occurred close by in 1945”, said Dr Fischer. “Based on several indicators, we postulated that the earthquake led to the fracturing of the sediments, releasing the gas that had been trapped below the hydrates into the ocean.”

The tremor was recorded at magnitude 8.1 – magnitude 9 is about as bad as an earthquake can be – and seismic waves would have raced through the seabed at colossal speeds, quite enough to shake loose any brittle chemical structures in the seabed.

The researchers estimate that the release of methane from that location since that one event could be conservatively estimated at 7.4 million cubic metres: this is roughly the capacity of 10 large gas tankers.

“…hydrocarbon seepage triggered by earthquakes needs to be considered in local and global carbon budgets at active continental margins…”

This calculation does not take into account how much escaped during the quake itself, and it holds for only one location. “There are probably even more sites in the area that had been affected by the earthquake”, said Dr Fischer.

Such research is another reminder of the complexity of the planet’s climate system. Methane hydrates can be considered as a form of fossil fuel: decayed plant material from millions of years ago, trapped in the mud under the pressing weight of the sea.

Climate scientists have for decades worried about the fragility of these hydrates – as the world warms, they are likely to be released in huge quantities from the Arctic seabed, for instance – but this is the first evidence that natural rather than human-triggered cataclysms could make a serious difference to the global carbon budget.

The lesson is that scientists now have to take such processes into account as they try to calculate the carbon budget for the planet – the quantities of greenhouse gases released into the atmosphere, the volumes subsequently absorbed by plants and then incorporated into sediments.

“We now provide a new mechanism of carbon export that had not been considered before”, said Dr Fischer, and with his co-authors he pushes the message home in the research paper. “We therefore suggest that hydrocarbon seepage triggered by earthquakes needs to be considered in local and global carbon budgets at active continental margins.” – Climate News Network

FOR IMMEDIATE RELEASE
Methane is a potent greenhouse gas which in the short term is a much greater threat to global temperatures than carbon dioxide. Now researchers think it can be released by earthquakes.

LONDON, 31 July – And here’s another shuddering twist to the horror story that is climate change: even earthquakes may play a role. Large quantities of methane may have escaped during a violent earthquake that shook the floor of the Arabian Sea in 1945, according to German and Swiss researchers.

David Fischer of the University of Bremen and colleagues from the Alfred Wegener Institute in Bremerhaven and the ETH in Zurich explored the region in a research ship in 2007, and began to examine cores of sediment from the seabed.

One core, from just 1.6 metres below the seabed, contained methane hydrate – an ice-like mixture of methane and water –  and the other did not. But, the researchers report in Nature Geoscience, both cores carried subtle chemical evidence that at some point in the past dramatic quantities of methane or natural gas had actually flowed through the sediments beneath the Arabian Sea.

Since the methane would move as a gas, there is only one direction it could go: bubbling upwards through the sea into the atmosphere. And since methane is a potent greenhouse gas – at least 23 times more potent than carbon dioxide – such escapes could be significant.

“We started going through the literature and found that a major earthquake had occurred close by in 1945”, said Dr Fischer. “Based on several indicators, we postulated that the earthquake led to the fracturing of the sediments, releasing the gas that had been trapped below the hydrates into the ocean.”

The tremor was recorded at magnitude 8.1 – magnitude 9 is about as bad as an earthquake can be – and seismic waves would have raced through the seabed at colossal speeds, quite enough to shake loose any brittle chemical structures in the seabed.

The researchers estimate that the release of methane from that location since that one event could be conservatively estimated at 7.4 million cubic metres: this is roughly the capacity of 10 large gas tankers.

“…hydrocarbon seepage triggered by earthquakes needs to be considered in local and global carbon budgets at active continental margins…”

This calculation does not take into account how much escaped during the quake itself, and it holds for only one location. “There are probably even more sites in the area that had been affected by the earthquake”, said Dr Fischer.

Such research is another reminder of the complexity of the planet’s climate system. Methane hydrates can be considered as a form of fossil fuel: decayed plant material from millions of years ago, trapped in the mud under the pressing weight of the sea.

Climate scientists have for decades worried about the fragility of these hydrates – as the world warms, they are likely to be released in huge quantities from the Arctic seabed, for instance – but this is the first evidence that natural rather than human-triggered cataclysms could make a serious difference to the global carbon budget.

The lesson is that scientists now have to take such processes into account as they try to calculate the carbon budget for the planet – the quantities of greenhouse gases released into the atmosphere, the volumes subsequently absorbed by plants and then incorporated into sediments.

“We now provide a new mechanism of carbon export that had not been considered before”, said Dr Fischer, and with his co-authors he pushes the message home in the research paper. “We therefore suggest that hydrocarbon seepage triggered by earthquakes needs to be considered in local and global carbon budgets at active continental margins.” – Climate News Network

Earthquakes ‘may add to methane leaks’

FOR IMMEDIATE RELEASE Methane is a potent greenhouse gas which in the short term is a much greater threat to global temperatures than carbon dioxide. Now researchers think it can be released by earthquakes. LONDON, 31 July – And here’s another shuddering twist to the horror story that is climate change: even earthquakes may play a role. Large quantities of methane may have escaped during a violent earthquake that shook the floor of the Arabian Sea in 1945, according to German and Swiss researchers. David Fischer of the University of Bremen and colleagues from the Alfred Wegener Institute in Bremerhaven and the ETH in Zurich explored the region in a research ship in 2007, and began to examine cores of sediment from the seabed. One core, from just 1.6 metres below the seabed, contained methane hydrate – an ice-like mixture of methane and water –  and the other did not. But, the researchers report in Nature Geoscience, both cores carried subtle chemical evidence that at some point in the past dramatic quantities of methane or natural gas had actually flowed through the sediments beneath the Arabian Sea. Since the methane would move as a gas, there is only one direction it could go: bubbling upwards through the sea into the atmosphere. And since methane is a potent greenhouse gas – at least 23 times more potent than carbon dioxide – such escapes could be significant. “We started going through the literature and found that a major earthquake had occurred close by in 1945”, said Dr Fischer. “Based on several indicators, we postulated that the earthquake led to the fracturing of the sediments, releasing the gas that had been trapped below the hydrates into the ocean.” The tremor was recorded at magnitude 8.1 – magnitude 9 is about as bad as an earthquake can be – and seismic waves would have raced through the seabed at colossal speeds, quite enough to shake loose any brittle chemical structures in the seabed. The researchers estimate that the release of methane from that location since that one event could be conservatively estimated at 7.4 million cubic metres: this is roughly the capacity of 10 large gas tankers.

“…hydrocarbon seepage triggered by earthquakes needs to be considered in local and global carbon budgets at active continental margins…”

This calculation does not take into account how much escaped during the quake itself, and it holds for only one location. “There are probably even more sites in the area that had been affected by the earthquake”, said Dr Fischer. Such research is another reminder of the complexity of the planet’s climate system. Methane hydrates can be considered as a form of fossil fuel: decayed plant material from millions of years ago, trapped in the mud under the pressing weight of the sea. Climate scientists have for decades worried about the fragility of these hydrates – as the world warms, they are likely to be released in huge quantities from the Arctic seabed, for instance – but this is the first evidence that natural rather than human-triggered cataclysms could make a serious difference to the global carbon budget. The lesson is that scientists now have to take such processes into account as they try to calculate the carbon budget for the planet – the quantities of greenhouse gases released into the atmosphere, the volumes subsequently absorbed by plants and then incorporated into sediments. “We now provide a new mechanism of carbon export that had not been considered before”, said Dr Fischer, and with his co-authors he pushes the message home in the research paper. “We therefore suggest that hydrocarbon seepage triggered by earthquakes needs to be considered in local and global carbon budgets at active continental margins.” – Climate News Network

FOR IMMEDIATE RELEASE Methane is a potent greenhouse gas which in the short term is a much greater threat to global temperatures than carbon dioxide. Now researchers think it can be released by earthquakes. LONDON, 31 July – And here’s another shuddering twist to the horror story that is climate change: even earthquakes may play a role. Large quantities of methane may have escaped during a violent earthquake that shook the floor of the Arabian Sea in 1945, according to German and Swiss researchers. David Fischer of the University of Bremen and colleagues from the Alfred Wegener Institute in Bremerhaven and the ETH in Zurich explored the region in a research ship in 2007, and began to examine cores of sediment from the seabed. One core, from just 1.6 metres below the seabed, contained methane hydrate – an ice-like mixture of methane and water –  and the other did not. But, the researchers report in Nature Geoscience, both cores carried subtle chemical evidence that at some point in the past dramatic quantities of methane or natural gas had actually flowed through the sediments beneath the Arabian Sea. Since the methane would move as a gas, there is only one direction it could go: bubbling upwards through the sea into the atmosphere. And since methane is a potent greenhouse gas – at least 23 times more potent than carbon dioxide – such escapes could be significant. “We started going through the literature and found that a major earthquake had occurred close by in 1945”, said Dr Fischer. “Based on several indicators, we postulated that the earthquake led to the fracturing of the sediments, releasing the gas that had been trapped below the hydrates into the ocean.” The tremor was recorded at magnitude 8.1 – magnitude 9 is about as bad as an earthquake can be – and seismic waves would have raced through the seabed at colossal speeds, quite enough to shake loose any brittle chemical structures in the seabed. The researchers estimate that the release of methane from that location since that one event could be conservatively estimated at 7.4 million cubic metres: this is roughly the capacity of 10 large gas tankers.

“…hydrocarbon seepage triggered by earthquakes needs to be considered in local and global carbon budgets at active continental margins…”

This calculation does not take into account how much escaped during the quake itself, and it holds for only one location. “There are probably even more sites in the area that had been affected by the earthquake”, said Dr Fischer. Such research is another reminder of the complexity of the planet’s climate system. Methane hydrates can be considered as a form of fossil fuel: decayed plant material from millions of years ago, trapped in the mud under the pressing weight of the sea. Climate scientists have for decades worried about the fragility of these hydrates – as the world warms, they are likely to be released in huge quantities from the Arctic seabed, for instance – but this is the first evidence that natural rather than human-triggered cataclysms could make a serious difference to the global carbon budget. The lesson is that scientists now have to take such processes into account as they try to calculate the carbon budget for the planet – the quantities of greenhouse gases released into the atmosphere, the volumes subsequently absorbed by plants and then incorporated into sediments. “We now provide a new mechanism of carbon export that had not been considered before”, said Dr Fischer, and with his co-authors he pushes the message home in the research paper. “We therefore suggest that hydrocarbon seepage triggered by earthquakes needs to be considered in local and global carbon budgets at active continental margins.” – Climate News Network