According to a statement from the researchers, these findings have left them asking, “Is there a lost world beneath the Pacific Ocean?” New Full-Waveform Inversion Method Reveals Lost World Beneath the Pacific Ocean When tectonic plates collide, one of them pushes itself underneath the other.
The result of this collision is something scientists call a “subduction zone” deep within the Earth’s mantle.
Because these subduction zones are too deep to measure directly, researchers typically use the speed of seismic waves caused by earthquakes to infer the material composition and location of subduction zones.
“With the new high-resolution model, we can see such anomalies everywhere in the Earth’s mantle.
“Essentially, we have to dive deeper into the material properties behind the wave speed.” The study “Full-waveform inversion reveals diverse origins of lower mantle positive wave speed anomalies” was published in Scientific Reports.
A global group of geophysicists claims to have found the remains of what looks to be a “lost world” beneath the Pacific Ocean by employing a novel imaging method that gauges the velocity of seismic waves produced by earthquakes to pinpoint the location of tectonic plate junctures in the Earth’s mantle.
These tectonic plate junctures have always been located where scientists expected them to be using earlier methods. However, geophysicists from the California Institute of Technology (Cal Tech) and ETH Zurich recently collaborated to discover signs of these zones at sites that show no signs of recent tectonic activity or tectonic plate movement.
These results have led the researchers to ask, “Is there a lost world beneath the Pacific Ocean?” they said in a statement.
Discover a Lost World Under the Pacific Ocean with a New Full-Waveform Inversion Method.
One tectonic plate pushes beneath the other when they collide. A “subduction zone” deep within the Earth’s mantle is what scientists refer to as the result of this collision. The speed of seismic waves produced by earthquakes is usually used by researchers to infer the location and material composition of subduction zones because these areas are too deep to measure directly.
The ETH-Cal Tech team’s novel method entails studying multiple earthquake wave types at once, whereas previous efforts usually involved monitoring the reflection, refraction, or diffraction of a single type of earthquake wave as it passes through the Earth’s mantle. Full-waveform inversion is the name of the procedure.
The team used this new process and, surprisingly, discovered evidence of subduction zones in a number of locations that show no recent geological history of tectonic activity. For instance, the subduction zone remnants found beneath vast oceans or inside continents were identified by the team’s model. None of these sites had any other indications of previous subduction and were all far from plate borders.
Because earlier seismic wave scanning techniques only used data from one kind of earthquake wave, the researchers claim that they simply missed these lost worlds. But according to the team, they discovered the enigmatic subduction zones they are referring to as “lost worlds” thanks to a completely new tool that their full-waveform inversion approach provided. “.”.
Andreas Fichtner, a professor at ETH and one of the authors of the published study described the discovery, said, “It’s like a doctor who has been examining blood circulation with ultrasound for decades and finds arteries exactly where he expects them.”. “Then, if you give him a new, improved examination tool, he finds an artery in his buttock that shouldn’t be there immediately.”. That’s precisely how we feel about the recent discoveries. “.”.
One zone found beneath the western Pacific Ocean piqued the team’s interest, according to the published study. The reason for this is that there shouldn’t be any subducted plate material there “because it is impossible that there were subduction zones nearby in the recent geological history.”. “.”.
Thomas Schouten, a first author and doctoral candidate at the Geological Institute of ETH Zurich, stated, “That is our dilemma.”. The new high-resolution model allows us to observe these anomalies throughout the Earth’s mantle. However, we have no idea what they are or what substance is causing the patterns we have found. “.”.
The scientist goes on to say, “Apparently, such zones in the Earth’s mantle are much more widespread than previously thought.”.
exploring the wave speed’s properties in greater detail.
The researchers say they are still unsure of what is causing these lost worlds to be found where they shouldn’t be because they don’t fit their typical models, despite the team’s strong evidence. According to Schouten, the team thinks there could be a “range of origins” for these anomalies, outside of a normal subduction zone.
“It could be either zones where iron-rich rocks accumulate as a result of these mantle movements over billions of years, or it could be ancient, silica-rich material that has been there since the mantle’s formation approximately 4 billion years ago and has survived despite the convective movements in the mantle,” the wave scientists explained.
In order to measure the earthquake waves passing through the material in even more detail, the team plans to use their full-wave inversion method to learn more about these zones in the future. Since their present measurements only look at data from one property, “namely the speed at which they travel through the Earth’s interior,” Schouten claims that additional data could be added to their analysis. “”.
The researcher clarified, “We need to compute the various material parameters that could produce the observed speeds of the various wave types.”. In essence, the material properties underlying the wave speed require further investigation. “.”.
In Scientific Reports, the study “Full-waveform inversion reveals diverse origins of lower mantle positive wave speed anomalies” was released.
