#subductionzone

#Cascadia #SubductionZone #earthquakes

"When an earthquake rips along the Cascadia Subduction Zone fault, much of the U.S. West Coast could shake violently for five minutes, and tsunami waves as tall as 100 feet could barrel toward shore. But that’s just the start of the expected horrors.

Even if coastal towns in Northern California, Oregon and Washington withstand that seismic onslaught, new research suggests, floodwaters could seep into many of these vulnerable communities for good. That’s because entire coastal shorelines are expected to drop by as much as 6½ feet when the earthquake strikes, according to new research published Monday in the Proceedings of the National Academy of Sciences."

nbcnews.com/science/earthquake

Benjamin Carr, Ph.D. 👨🏻‍💻🧬BenjaminHCCarr@hachyderm.io
2025-02-10

Unexpected And Unexplained Structures Found Deep Below The Pacific Ocean
There are zones where the seismic waves move in different ways, suggesting structures that are colder or have a different composition than the surrounding molten rock.
It is unclear what these structures are. If they were anywhere else, they could be portions of #tectonicplates that have sunk in a #subductionzone. But the Pacific is one large plate, so there should be no subduction material under it. iflscience.com/unexpected-and-

Benjamin Carr, Ph.D. 👨🏻‍💻🧬BenjaminHCCarr@hachyderm.io
2024-10-21

#Geologists Uncover Mysterious Hidden #SubductionZone Beneath #Pacific, Offering A Glimpse into Earth's Ancient Interior
This discovery reveals a hidden chapter of Earth’s history that reshapes our understanding of the planet’s inner workings. This hidden tectonic boundary, buried over 250 million years ago, challenges prevailing theories about Earth’s interior structure and offers insights into how the planet’s surface has evolved over millennia.
thedebrief.org/geologists-unco

earthlingappassionato
2024-08-30
WeAreSeismicaweareseismica
2024-07-02

What causes onshore faults to slip in subduction zones?

Well, it turns out that the commonly held reason does not apply to the faults located in northern Cascadia.

Read Harrichhausen et al. to find out why: seismica.library.mcgill.ca/art

WeAreSeismicaweareseismica
2024-06-16

The publications for the Cascadia Subduction Zone special issue are starting to come out, check them out here:
seismica.library.mcgill.ca/iss

Don’t miss out on contributing to this Seismica special issue!
Scope, topics, publication types, and conditions:
seismica.library.mcgill.ca/ann

WeAreSeismicaweareseismica
2024-06-11

Is there any evidence of Slow Slip Events in the southern Peru-northern Chile subduction zone?

Yes, Jara et al. find tiny events hidden in the geodetic noise. Read more to see how they detected and characterized them:
seismica.library.mcgill.ca/art

Smitha 🌸🌋🎻smitha@kind.social
2024-05-17

Really was not expecting to hear the name #Shimanto (AKA #KochiPrefecture) in a lecture about the #Cascadia / #JuanDeFuca fault.

The Shimanto Mountains were mentioned as an analog of our own #OlympicMountains - both are non-volcanic, near a #megathrust #SubductionZone (#NankaiTrough for Japan: major #earthquake every 100-200 years), and contain remnants of paleomegathrust (new fave word) fault lines thanks to historic and ongoing subduction.

As terrifying as it can be, I love #geology so much.

2024-03-18

News blips: Havana syndrome evaporates and headlines burn up about plate tectonics

Today I have two news clips to share that should teach us some lessons. Lessons are only learned if you can withhold your biases, employ some critical thinking, and pay attention to blatantly silly attempts to get you to be scared and click on stuff.

Cause of Havana syndrome evaporates

I’ve been following stories about “Havana syndrome” since it emerged in 2016. At that time, I was doing the podcast, 15 Credibility Street, and it seemed really obvious even at that time that this condition, where government officials and military personnel were experiencing sometimes vague but serious symptoms associated with what they thought was a directed weapon, was at least to some degree a psychological illness brought on by stress. But the headlines grabbed attention by highlighting the threat of a secret, hidden weapon that could target individuals and then disappear without a trace.

The first serious study of those who suffered from it didn’t find anything notable regarding brain injuries, however, the researchers speculated that the victims suffered injury to the brain network that resulted in the symptoms. The study was roundly criticized, particularly when one of the researcher, followed by others who wanted their opinions heard, irresponsibly promoted the idea of a microwave or sonic weapon. Far less attention was given to experts in technical weaponry, who insisted there was no such technology.

As the years went by, even though more people claimed to suffer from the condition, the effort to pin down a specific cause faltered. Every day that went by with no evidence of a smoking gun means that the proposed mystery weapon conclusion is likely wrong. All signs always pointed to mass psychogenic illness, a serious condition that can have devastating results. We have many solid cases of mass psychogenic illness throughout history, yet it remains an unsatisfying, misunderstood and strongly stigmatized diagnosis that inevitably is rejected by the victims, and the public.

At the same time as the emergence of Havana syndrome, another rather clear example of mass psychogenic illness was winding down – the case of mass “hysteria” in a school in Leroy, New York. Many teen girls in a Leroy school suffered from involuntary motor and vocal tics that resembled those associated with Tourette syndrome. An environmental cause was suspected. But, again, there wasn’t one found. The problem was coming from inside the patient herself. Almost no one was satisfied with that answer.

Our history of mass psychogenic illness was never learned. Thus, Havana syndrome, later named with an acronym to dissuade the political insinuations, marched on in the public view as having a threatening mystery cause.

Today, additional news is out regarding Havana syndrome as two more papers are out that should dissolve the idea of a secret weapon. This thorough study produced findings of no physical causes for the condition.

Using advanced imaging techniques and in-depth clinical assessments, a research team at the National Institutes of Health (NIH) found no significant evidence of MRI-detectable brain injury, nor differences in most clinical measures compared to controls, among a group of federal employees who experienced anomalous health incidents (AHIs). These incidents, including hearing noise and experiencing head pressure followed by headache, dizziness, cognitive dysfunction and other symptoms, have been described in the news media as “Havana Syndrome” since U.S. government personnel stationed in Havana first reported the incidents. Scientists at the NIH Clinical Center conducted the research over the course of nearly five years and published their findings in two papers in JAMA today.

“Our goal was to conduct thorough, objective and reproducible evaluations to see if we could identify structural brain or biological differences in people who reported AHIs,” said Leighton Chan, M.D., chief, rehabilitation medicine and acting chief scientific officer, NIH Clinical Center, and lead author on one of the papers. “While we did not identify significant differences in participants with AHIs, it’s important to acknowledge that these symptoms are very real, cause significant disruption in the lives of those affected and can be quite prolonged, disabling and difficult to treat.”

Nat Institutes of Health press release, March 18, 2024

This was a valid attempt made to find a physical cause, as were the other studies that actually found no cause either. It’s not there to be found. This should mean the case is closed. But I suspect it won’t be.

The government spent considerable funds attempting to address the syndrome, even to the point of moving ahead with funding a study involving animal research to try to replicate the condition. In light of the current findings, it is unethical to continue any research into physical causes of the condition. There is likely not one single cause of the symptoms.

Notably, the body of evidence always pointed away from the idea of a targeted weapon. But that didn’t stop certain bigmouths from hyper focusing on some facts and ignoring others, hyping their dramatic cause. The media amplified this erroneous view, which was reprehensible. The lesson is to double-check the original sources, not only what the media puts out. Even legitimate experts tripped themselves up on this in an effort to be in the news and gain attention. To get the full story, you have to critical examine several good sources. I hope the result of this awful period of American history is that more people heard of and will ultimately accept the concept of mass psychogenic illness so we can recognize it and act more appropriately the next time it arises. (But I doubt it.)

Atlantic Ocean news conflagration

The second story follows from the first, where writers used a deceptive and stupid headline to mislead readers into believing another catastrophe is around the corner. I wonder if some Chicken Little is running around yelling that the ocean is closing…

The real news: Researchers using advanced modeling tools showed that the existing Gibraltar subduction zone, which many thought was dormant, may evolve in the geologic future and reactivate, expanding into the Atlantic Ocean and possibly creating a tectonic condition that will eventually close the ocean basin beginning around 20 million years from now.

That’s pretty interesting stuff. It’s only a model, though, but it can help geoscientists understand more about plate tectonics and how subduction zones form. Subduction zones can produce massive earthquakes and lines of volcanoes. The Pacific Ocean is becoming smaller every millennia as the ocean crust is subducted under the continental plates, forming the “Ring of Fire” of volcanoes and seismic zones.

Earth.com: The Atlantic Ocean may soon enter its declining phase

How did some ridiculous media interpret this new finding? Stupidly, of course. (Good old Daily Fail takes the prize with worse headline.)

That’s just great. Look, we have enough actual calamities to deal with. There is no excuse for scaring people over a geologic event that isn’t going to be an issue for another 20 million years. I suspect the ongoing news about Icelandic eruptions means that people, including journalists with no science background, have scary-looking eruptions on their minds.

At least people might be learning something about geology if they are clicking on these headlines. If people are only reading the headlines, however, which most do, they are becoming remarkably dumber from the news because they will assume things that aren’t actually factual. I’m sure the researchers hate this. I know I do.

#anomalousHealthIncidents #AtlanticOcean #HavanaSyndrome #massPsychogenicIllness #massSociogenicIllness #plateTectonics #ringOfFire #subductionZone

https://sharonahill.com/?p=8470

WeAreSeismicaweareseismica
2023-11-17

Yani-Quiyuch et al. examine aftershocks of the 2022 Mw 6.2 earthquake in Guatemala, revealing these occurred on an intraplate fault between a double seismic zone, and identify normal and inverse focal mechanisms during the seismic sequence.

Read more: doi.org/10.26443/seismica.v2i2

WRITER FUEL: Scientists find weird holes on the ocean floor spewing ancient fluids 'like a fire hose' from under the tectonic plates.

limfic.com/2023/08/03/writer-f

#Geology #WriterFuel #Earth #SubductionZone #TectonicPlates

four holes on the ocean floor spewing liquids
Vicky Veritasvickyveritas@c.im
2023-01-03

The Wilson Cycle: Intro

“If the continents have moved, then they have drifted like rafts and formed the ocean floors in their wake. It is to this wake that we should look first.”
~ John Tuzo Wilson

Canadian geophysicist and geologist, John Tuzo Wilson, posed the question (and the title of his article in 1966) - ‘Did the Atlantic close and then re-open?’ Spoiler alert - yes. That, and his many contributions to plate tectonics, including the concept of hotspots and transform faults, led to the Wilson Cycle (also known as the Supercontinent Cycle) being named after him.

The Wilson Cycle (WC) refers to the process of continent break-up and ocean-opening followed by subduction, collision, ocean-closing, and continent formation (see the diagram below). This can take tens to hundreds of millons of years (very deep time) to complete.

This quick video provides animation of the WC: youtu.be/I_q3sAcuzIY

Step 1 of the WC starts with a tectonically stable continent/craton, eroded down and perhaps scarred by earlier collisions. Rifting (or faulting), crustal thinning, and thermal uplift caused by tectonic stretching of the continent allows the upper mantle (plume) to rise up and fill in. This can lead to earthquakes and volcanic flows. Sometime the plume can die out leading to a failed rift, but when rifting continues, things get quite interesting.

Step 2 The fractures are deep and oriented perpendicular to the extensional direction. As the continent breaks apart, the plume develops convection cells that further the rifting and deepen the basin allowing water in. The mantle material exposed by the rifting is made of much denser (or mafic) material than continental crust (or felsic) and sinks, cools and hardens/crystallizes forming oceanic crust. A new ocean basin is created.

Step 3 The two new continents continue to drift apart; the rift becomes a young spreading ridge, and the new ocean crust sinks further into the mantle as it cools and becomes denser. Sediment is now collecting on the new ocean floors.

Step 4 The Mid Ocean Ridge (MOR) continues to create new ocean crust and the new ocean deepens as the oceanic crust matures and continues to sink into the mantle. The mature oceanic crust is much heavier than the bordering continental crust, and cracks can develop causing the oceanic crust to flex downwards forming a young subduction zone. Part of the oceanic crust is dragged deep into trench and the water-laden oceanic crust melts due to the higher temperatures of the mantle. Volcanic Island arcs are created. The rifted continental crust is now well below the surface of the ocean.

Step 5 Divergence ceases, and convergence begins. The MOR is eventually subducted, or consumed at the ocean basin margin. Associated volcanism and subduction continues, along with collision, narrowing the ocean and causing mountains to form. This is now part of the ocean-closing cycle.

Step 6 As the continents/cratons continue to collide, folding, faulting, and earthquakes occur creating new mountains (think of the Himalayas), while catching up bits of volcanic rock, oceanic crust and sedimentary rock. A new continent is formed.

Step 7 The continent matures and erodes. Rinse and repeat with continents colliding, eventually forming supercontinents, and dispersing again in a much longer and even deeper time.

The Wilson Cycle is somewhat simplified and doesn’t go into all the sorts of tectonic variations of rift zones and diversity of plate tectonics, but it was a landmark starting point and a sign of Wilson’s genius. Later geologists and geophysicists stand on the shoulders of this giant. We’ll dive further into the Wilson Cycle in future posts, and have a look at the rock types created and how geologists piece together the Wilson Cycle in real rocks. It’ll be fun she said :)

#WilsonCycle #JohnTuzoWilson #OceanicCrustFormation #Mantle #Plume #MidOceanRidge #SubductionZone #MountainForming #geology #ScienceMastodon @geology

From Fifty years of the Wilson Cycle concept in plate tectonics: an overview by R. W. Wilson et. al. The six-stage Wilson Cycle of opening and closing of basins as proposed by Wilson (1968).

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