oleh admin | Jan 10, 2025 | earth science, earthquakes, geology, science, seismology
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EXPLORE FURTHER: The Enigma of Over 100 Quakes That Hit Surrey
is solved
From Atlantis to El Dorado and Avalon, legends suggest that our planet is scattered with vanished realms that suffered spectacular fates.
Although these are often regarded as creative legends, recent research uncovers proof of a ‘vanished realm’ under the Pacific Ocean.
Researchers from ETH Zurich and the
California
The Institute of Technology (Caltech) has discovered massive formations deep under the Pacific Ocean that theoretically shouldn’t be there.
This mystery material – which is making seismic waves in the region behave strangely – could be evidence of a lost land from hundreds of millions of years ago.
Based on present scientific theories, the unusual material located in the lower mantle, approximately 600 miles (1,000 km) under the ocean surface, ‘ought not to be present’ there.
Referred to as a significant enigma, these discoveries challenge ‘our present comprehension of how our planet functions,’ stated the scientists involved.
“The team, in their paper published in various journals, emphasize that understanding Earth’s structure is crucial for deciphering its internal movements,” they state.
Scientific Reports
.
These discoveries indicate a greater variety of sources for these irregularities in Earth’s lower mantle.
The Earth consists of three layers: the crust, the mantle, and the core, as identified subsequently.
divided into ‘internal’ and ‘external’ parts
.
The issue is that nobody can observe what lies beneath the Earth’s surface, and drilling deep enough to collect rock samples from the mantle is impossible for us.
Rather than directly observing Earth’s insides, researchers examine the velocities of seismic waves – the tremors triggered by quakes and blasts – as these waves move through our planet’s depths.
Seismograph stations capture these waves, and from these records, experts can deduce information regarding the Earth’s structure and makeup.
‘ETH Zurich explained that this process closely resembles how medical professionals utilize ultrasound technology to visualize internal structures such as organs, muscles, or blood vessels within the body without requiring surgical intervention.’
It is widely recognized that Earth’s lithosphere—the rocky exterior layer consisting of the upper part of the mantle and the crust—is made up of approximately 15 tectonic plates.
Earthquakes can be identified around the edges of tectonic plates, where these massive sections grind against one another.
However, long ago, substantial tectonic plates vanished beneath Earth’s surface through a process known as ‘subduction.’
What methods do scientists use to learn about Earth’s inner structure?
Nobody can observe what lies within the Earth, and drilling isn’t sufficient to obtain rock specimens from the mantle—the layer located between the planet’s core and crust.
Therefore, geophysicists employ indirect techniques to understand what lies far below our surface.
For instance, they utilize seismograms, which are records of earthquakes, to ascertain the velocity at which seismic waves travel.
They subsequently utilize this data to determine the Earth’s interior composition—much like physicians employ ultrasounds to visualize the insides of the human body.
This is the geological process where one tectonic plate gets thrust beneath another, and gradually, an entire plate can disappear.
Previously, seismologists have located submerged tectonic plates across the Earth’s mantle, though these were consistently found beneath subduction zones.
In their latest research, scientists from ETH Zurich and Caltech employed a computational method known as ‘full-waveform inversion.’ This approach generates a three-dimensional representation of the Earth’s structure utilizing seismic wave information.
They pinpointed regions beneath the Pacific that appear to be remnants of sunken tectonic plates, yet these zones are situated far from plate edges without any geologic signs of previous subduction activity.
The Pacific Plate is essentially one single tectonic plate, which means there shouldn’t be any subducting material beneath it at all.
This implies that the anomalies are not simply submerged tectonic plates. Nevertheless, identifying the actual nature of this material—or understanding its implications for the dynamic processes within the Earth—remains a mystery.
“It’s akin to a physician who has spent years using ultrasounds to examine blood flow and discovers arteries precisely where they should be,” stated co-author Professor Andreas Fichtner, a seismologist at ETH Zurich.
‘If you provide him with a more advanced examination tool, he abruptly detects an artery in the buttocks that shouldn’t actually be present. This precisely mirrors our reaction to these new discoveries.’
Nevertheless, the researchers offer several hypotheses regarding the anomalies, suggesting that these would require additional data beyond just wave speeds to draw any firm conclusions.
These might consist of ancient, high-silica substances that have remained within the mantle from its inception around four billion years ago.
Instead, these areas might be regions where iron-rich rocks gather due to mantle activity spanning millions of years.
They state in their paper, “There are various possible interpretations for the observation of positive wave speed anomalies within Earth’s (lower) mantle besides the existence of subducted slabs.”
‘Our study highlights the essential function of full waveform inversion as a crucial technique for exploring the mantle.’
Read more
oleh admin | Des 2, 2024 | earth, earth science, environment, science, venus
WASHINGTON – The Earth is essentially an oceanic planet, with approximately 71% of its surface submerged under water. Venus, our nearest celestial counterpart, is occasionally referred to as Earth’s sister due to similarities in mass and structure. Despite its current scorched and desolate landscape, could Venus have originally possessed vast bodies of water like ours?
According to recent findings, which estimated the water content within the planet’s inner layers—a crucial factor in determining if Venus ever possessed vast bodies of water—the answer is negative. These scientists determined that the planet’s core likely lacks significant moisture, aligning with theories suggesting Venus became extremely arid following an initial period where its exterior was primarily made up of molten material—magma—and since then has maintained a bone-dry landscape.
Water is deemed essential for sustaining life, hence the research indicates that Venus has never been inhabitable. The new evidence does not back up earlier theories suggesting that Venus might contain subsurface water reserves from a vanished ocean.
Volcanic activity, through the release of gases into a planet’s atmosphere, offers insights into the composition of terrestrial planets’ interiors. When magma moves upward from a deep internal zone known as the mantle towards the crust, it brings with it various substances originating from lower layers within the Earth.
On Earth, volcanic gases consist of over 60% water vapor, suggesting a water-abundant interior. In contrast, studies found that the gases from Venusian volcanoes contain at most 6% water vapor, pointing towards an extremely dry inner composition.
“We suggest that a habitable past would be associated with Venus’ present interior being water-rich, and a dry past with Venus’ present interior being dry,” said Tereza Constantinou, a doctoral student at the University of Cambridge’s Institute of Astronomy and lead author of the study published on Monday in the journal Nature Astronomy.
“Atmospheric chemistry indicates that volcanic eruptions on Venus emit minimal amounts of water, suggesting that the planet’s interior—the origin of these eruptions—is also largely devoid of moisture. This aligns with the idea that Venus has maintained a consistently arid surface for an extended period and was never hospitable,” Constantinou noted.
Venus is the planet that orbits as the second closest to the Sun, with Earth following as the third.
“There are two contrasting theories about water history on Venus: one suggests it maintained a mild climate for eons with bodies of surface water, whereas the alternative proposes that an initially scorching-hot Venus never managed to form any surface liquids,” as stated by Constantinou.
The diameter of Venus, approximately 7,500 miles (12,000 km), is slightly smaller than Earth’s, which measures around 7,900 miles (12,750 km).
“Venus and Earth are frequently referred to as sister planets due to their comparable mass, radius, density, and proximity to the Sun. Nevertheless, their developmental trajectories took very different directions,” Constantinou stated.
“Currently, Venus boasts surface conditions that are vastly different from those on Earth, characterized by an atmospheric pressure 90 times higher, surface temperatures reaching approximately 465°C (869°F), and a hazardous atmosphere filled with sulfuric acid clouds. These significant differences highlight the distinct difficulties involved in comprehending Venus beyond merely considering it as Earth’s twin,” stated Constantinou.
It seems the narrative was distinct on Mars, which is the fourth planet from the sun.
Mars shows signs of having once possessed vast oceans filled with liquid water billions of years back. In contrast, similar characteristics haven’t been observed on Venus. Research from August, which analyzed seismic information gathered by NASA’s automated InSight rover, suggests that Mars might contain a significant underground body of liquid water trapped beneath layers of fragmented volcanic rock. This accumulation could potentially flood the whole planet as one enormous sea.
Although Venus hasn’t received as much attention as Mars, upcoming missions aim to change this. In the 2030s, NASA’s proposed DAVINCI mission intends to study Venus thoroughly—from its atmosphere all the way to its surface—by employing both flybys and a descending probe. Similarly, during the same decade, the European Space Agency plans to launch their EnVision orbiter which will focus on conducting detailed radar imaging of Venus along with comprehensive atmospheric research.
“Venus serves as a natural lab for examining how conditions suitable for life—or the absence of them—develop,” stated Constantinou.
— Reuters
This article
Was there ever water on Venus? Scientists now know for sure.
was originally published in
GMA News Online
.
oleh admin | Sep 2, 2024 | earth, earth science, engineering, geology, science
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Scientists identified a torus-like area at the upper boundary of the outer core.
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This less dense area aids in agitating the molten metal, thereby producing the magnetic field.
Researchers have discovered an enormous ring-like formation hidden deep below the surface.
Scientists from the Australian National University utilized seismic waves created by
earthquakes
to gaze into the Earth’s enigmatic liquid center.
By following the trajectory of these waves throughout the Earth, scientists discovered a layer approximately hundreds of kilometers deep where their speed decreased by two percent compared to usual.
The doughnut-shaped formation encircles the Earth’s liquid outer core along an equatorial path, potentially playing a key role in generating our planet’s shielding magnetic field.
Professor Hrvoje Tkalčić, who led the research, states: “The magnetic field is an essential component required for sustaining life on Earth’s surface.”
Our planet consists of four primary layers.
the exterior crust, the partly molten mantle, a fluid metallic outer core, and a solid metallic inner core.
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When the movement of tectonic plates in the crust creates earthquakes, these produce vibrations that spread out through all the other layers of the Earth.
Leveraging the global network of seismic monitoring stations,
Scientists can observe how the waves propagate and use this information to forecast the circumstances beneath the water’s surface.
Researchers typically focus on the large, strong wavefronts that circulate globally within the initial hour following an earthquake.
Nevertheless, Professor Tkalčić and his co-author Dr. Xiaolong Ma managed to identify this pattern by examining the subtle remnants of waves that persisted for several hours following the primary shock.
The technique demonstrated that seismic waves propagating close to the poles were traveling at a quicker pace compared to those nearer to the equator.
When they compared their findings with various models of the Earth’s interior, Professor Tkalčić and Dr Ma discovered that these observations were most accurately described by the existence of an extensive subterranean ‘torus’, essentially a doughnut-shaped area.
They forecast that this area is located solely at low latitudes and aligns with the equator close to the upper boundary of the outer core, where the liquid part interfaces with the mantle.
“We aren’t certain about the precise thickness of the doughnut, but we deduced that it extends several hundred kilometers below the core-mantle boundary,” states Professor Tkalčić.
Due to the vital importance of this area, their discovery might also hold significant consequences for understanding life on our planet and beyond.
The Earth’s outer core extends about 2,160 miles (3,480 km), which is somewhat bigger than the size of Mars.
Primarily composed of molten nickel and iron, convection currents combined with the planet’s spin drive the fluid metals in this region into elongated vertical whirls oriented from north to south, similar to colossal water tornadoes.
The rotating flows within these molten materials function akin to a dynamo, generating the Earth’s magnetic field.
As this donut-shaped area has risen to the upper part of the liquid outer core, it implies that it might contain an abundance of lighter elements such as silicon, sulfur, oxygen, hydrogen, or carbon.
Professor Tkalčić states: “Our discoveries are intriguing as this reduced speed within the liquid core suggests a significant presence of lightweight chemical elements in those areas, which would consequently decelerate the seismic waves.”
These lightweight components, along with variations in temperature, assist in agitating the fluid within the outer core.
Without that vigorous movement to power the planet’s internal dynamo, Earth’s magnetic field may not have come into existence.
In the absence of the magnetic field, the planet’s surface would face an unrelenting assault from charged particles.
From the sun, which has the power to damage the genetic material of living organisms.
This ring-like area could thus be an essential clue in understanding how life originated on Earth and what signs we should search for when identifying potentially livable exoplanets.
Dr. Tkalčić concludes: “Our findings might encourage further investigation into the magnetic fields of both our planet and others.”
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