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Tsunami & Mega-Tsunami

STAAAAP with the Canary Island megatsunami drama!

https://blogs.agu.org/landslideblog/2013/12/13/canary-islands-tsunami/
"To generate a very large tsunami, this slide would have to happen very fast and as an essentially coherent block. Remember that this is a landslide of 500 cubic kilometres – we do not think that very, very large landslides usually behave like this. The chances are that a collapse would occur in stages over a longer time period, which would generate a much smaller wave. Most scientists recognise that the single, intact block collapsing very fast idea is theoretically possible, but that it is the extreme end-member of a wide range of scenarios, and thus is highly unlikely."
 

Did a tsunami crash into Welsh coast over 400 years ago?



In what is almost certainly Britain's greatest natural disaster, over 400 years ago around 2,000 people lost their lives when a huge wave crashed thundered up the Bristol channel, drowning miles of south Wales.


But 412 years later, questions remain about whether the Welsh coast was battered by a freak tsunami, or a powerful storm surge facilitated by inadequate flood defences.


Either way, the irresistible force which caused a trail of devastating destruction around the coastline washed away buildings, destroyed hundreds livestock and even killed thousands of people.
(c) WoL '21
 

A tsunami in South Wales? The 1607 flood in the Bristol Channel and Severn Estuary



 
Tsunami hits Tonga, following underwater eruption.

tsunami.png


https://www.bbc.co.uk/news/world-asia-60007119
 
The time lapse image of the volcano going off is unreal. Those poor people! An unwelcome reminder of the power of a really big volcano, and there's a few of them about. Maybe we're due another Krakatoa?
 
The time lapse image of the volcano going off is unreal. Those poor people! An unwelcome reminder of the power of a really big volcano, and there's a few of them about. Maybe we're due another Krakatoa?
Yellowstone might happen.
 
The sight of the ash cloud dwarfing the entire islands of Tonga, the fact that internet and comms are down and very little news has come from Tonga yet, the thought of the size of the waves...

It's somewhat surprising that there does not seem to be anticipation of widespread devastation for Tonga? Kind of feels like we should be preparing for some horrendous news from the Pacific in the coming days. No?
 
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I wonder what the effects might be on weather going forward - is it throwing enough dust up into the atmosphere to be noticeable long term ?
 
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I wonder what the effects might be on weather going forward - is it throwing enough dust up into the atmosphere to be noticeable long term ?

According to this Live Science article - the first I've seen on prospects for weather / climate effects - the answer is 'No'. The Tonga blast pushed volcanic ash to a record (documented) altitude in the atmosphere, but the amount of ash and sulfur dioxide emitted was relatively low compared to other documented eruptions of similar scale.
Ash from Tonga volcano eruption reaches record altitude but climate cooling unlikely

The Tonga volcanic eruption was the most powerful our planet has experienced in 30 years.

The volcanic eruption that destroyed a small island in Polynesia on Saturday (Jan. 15) injected a huge amount of ash into a record altitude but won't cause any disruption to Earth's climate, experts said.

Satellites detected the ash cloud, which has already spread over Australia, at over 24 miles (39 kilometers) above Earth's surface, Oxford University research fellow Simon Proud said on Twitter on Monday (Jan. 17). This was the first time volcanic ash has been detected so high in Earth's atmosphere, he added.

"Based on analysis of data from global weather satellites, our preliminary data for the Tonga volcanic cloud suggests that it reached an altitude of 39km [24 miles]," Proud said. "We'll refine the accuracy of that in the coming days, but if correct, that's the highest cloud we've ever seen."

Scientists, however, think that the eruption won't affect Earth's climate. Despite the apocalyptic proportions of the blast, which was documented in real time by several satellites, the amount of ash it contained was relatively small compared to other cataclysmic volcanic eruptions known from previous centuries. ...

Supervolcanoes like Tonga that spurt vast quantities of sulfur dioxide into higher layers of Earth's atmosphere can sometimes produce a measurable cooling effect on the planet's climate. This effect was detected, for example, after the 1991 eruption of Mount Pinatubo in the Philippines. ... But according to available data, Tonga blasted into the atmosphere only 400,000 metric tonnes of sulfur dioxide, about 2% of the amount of Mount Pinatubo. ...
FULL STORY: https://www.livescience.com/tonga-volcano-ash-record-altitude
 
This is unsettling ... In August 2021 a tsunami spread from the South Atlantic Ocean northward as well as east and west into the Indian and Pacific Oceans. Its origin was something of a mystery because it resulted from a compound set of major earthquakes, some of which were too deep to register as significant on the usual seismological monitoring systems. In other words, the severity of the quake effects was overlooked and the extent of the tsunami was unexpected. This incident indicates some upgrades to monitoring and alerting systems are required.
Mystery Tsunami That Spread Around The World in 2021 Can Finally Be Explained

Last year in August, a surprise tsunami in the South Atlantic Ocean mushroomed to distances over 10,000 kilometers (more than 6,000 miles) away, rippling through the North Atlantic, the Pacific, and the Indian Oceans.

It was the first time a tsunami had been recorded in three different oceans since the 2004 Indian Ocean earthquake, and scientists have only just now figured out how the waves were triggered.

The epicenter of the August earthquake was measured 47 kilometers (about 30 miles) below the ocean floor, which is much too deep to initiate a significant tsunami, even one with relatively small waves between 15 and 75 centimeters tall (6 to 30 inches).

As it turns out, however, this tsunami wasn't just the product of a single 7.5-magnitude earthquake. A fresh look at the seismological data suggests it was actually a series of five sub-quakes, and in their midst, was hiding a much larger and shallower rumble that was probably what set loose the global tsunami.

This 'invisible' third quake struck just 15 kilometers below the Earth's surface at a magnitude of 8.2. Yet in the crowd of quakes, our monitoring systems completely missed it.

"The third event is special because it was huge, and it was silent," explains seismologist Zhe Jia from the California Institute of Technology.

"In the data we normally look at [for earthquake monitoring], it was almost invisible." ...
FULL STORY: https://www.sciencealert.com/we-jus...-tsunami-in-2021-took-us-by-complete-surprise

PUBLISHED RESEARCH REPORT:
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2021GL097104
 
Chilean researchers have found evidence of an ancient earthquake-induced mega-tsunami so catastrophic it seems to have driven long-established coastal populations inland for a millennium. Its effects were dire as far away as New Zealand.
An Atacama Super-Quake We Never Knew About Sent Humans Into Hiding For 1,000 Years

A gigantic tsunami-unleashing earthquake that struck northern Chile 3,800 years ago wreaked such devastation on coastal populations, it took 1,000 years for humans to return to the shore, scientists say. ...

The ancient super-quake would have had a magnitude of around 9.5, and was so powerful it generated a tsunami that hurled boulders hundreds of meters inland in New Zealand, which is thousands of miles – and an entire ocean – away.

The discovery is evidenced by uplifted land structures (aka littoral deposits) and samples of marine rocks, shells, and sea life washed far ashore by tsunami waves into the higher stretches of Chile's Atacama Desert. It serves as a grim warning of the destructive potential of major tsunamigenic earthquakes that may have previously escaped our notice. ...
FULL STORY: https://www.sciencealert.com/feroci...about-sent-humans-into-hiding-for-1-000-years
See Also: https://www.southampton.ac.uk/news/2022/04/ancient-super-earthquake.page
 
Here are the bibliographic details and abstract for the published research paper. The full paper is accessible at the link below.


Did a 3800-year-old Mw ~9.5 earthquake trigger major social disruption in the Atacama Desert?
DIEGO SALAZAR, GABRIEL EASTON, JAMES GOFF et al.
SCIENCE ADVANCES • 6 Apr 2022 • Vol 8, Issue 14
DOI: 10.1126/sciadv.abm2996

Abstract

Early inhabitants along the hyperarid coastal Atacama Desert in northern Chile developed resilience strategies over 12,000 years, allowing these communities to effectively adapt to this extreme environment, including the impact of giant earthquakes and tsunamis. Here, we provide geoarchaeological evidence revealing a major tsunamigenic earthquake that severely affected prehistoric hunter-gatherer-fisher communities ~3800 years ago, causing an exceptional social disruption reflected in contemporary changes in archaeological sites and triggering resilient strategies along these coasts. Together with tsunami modeling results, we suggest that this event resulted from a ~1000-km-long megathrust rupture along the subduction contact of the Nazca and South American plates, highlighting the possibility of Mw ~9.5 tsunamigenic earthquakes in northern Chile, one of the major seismic gaps of the planet. This emphasizes the necessity to account for long temporal scales to better understand the variability, social effects, and human responses favoring resilience to socionatural disasters.

SOURCE / FULL REPORT: https://www.science.org/doi/10.1126/sciadv.abm2996
 
Could megatsunamis following the Burckle crater event be behind the global flood legends?
Some 5,000 to 6,000 years ago, what is thought to have been a cometary impact, left a 29km diameter crater in the Indian Ocean.
This produced catastrophic megatsunamis in the Indian Ocean but also vaporized millions of tons of seawater that took days to cool into rain and would have been transported thousands of kilometres on global winds. Thus, suggests this report, an event of this magnitude could be the source of deluge legends not just around the Indian Ocean, but in Africa, Australia, Europe and Asia too.
The comet was thought to be friable - meaning it broke into fragments, with at least two other major strikes occurring in the Earth's oceans and smaller fragments hitting the land.
Long, but very readable PDF is at the link below.

burckle.png



https://academiccommons.columbia.edu
 
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Until I read an article about it on yesterday's Quora, I must admit that I hadn't heard of the Burckle event.
The energy of an impact that could leave a 29km crater in thousands of metres of ocean almost beggars belief.
Chevron dunes detectable today in Madagascar and the west coast of Australia are thought to be relict evidence of the megatsunamis caused by the impact.
I can certainly find it plausible that this was behind the deluge legends around the world.
 
The Burckle impact / crater was mentioned back in 2006 in the Holocene Impact Working Group thread.

... About 900 miles southeast from the Madagascar chevrons, in deep ocean, is Burckle crater, which Dr. Abbott discovered last year. Although its sediments have not been directly sampled, cores from the area contain high levels of nickel and magnetic components associated with impact ejecta.

Burckle crater has not been dated, but Dr. Abbott estimates that it is 4,500 to 5,000 years old.

It would be a great help to the cause if the National Science Foundation sent a ship equipped with modern acoustic equipment to take a closer look at Burckle, Dr. Ryan said. “If it had clear impact features, the nonbelievers would believe,” he said.

But they might have more trouble believing one of the scientists, Bruce Masse, an environmental archaeologist at the Los Alamos National Laboratory in New Mexico. He thinks he can say precisely when the comet fell: on the morning of May 10, 2807 B.C.

Dr. Masse analyzed 175 flood myths from around the world, and tried to relate them to known and accurately dated natural events like solar eclipses and volcanic eruptions. Among other evidence, he said, 14 flood myths specifically mention a full solar eclipse, which could have been the one that occurred in May 2807 B.C.

Half the myths talk of a torrential downpour, Dr. Masse said. A third talk of a tsunami. Worldwide they describe hurricane force winds and darkness during the storm. All of these could come from a mega-tsunami.

Of course, extraordinary claims require extraordinary proof, Dr. Masse said, “and we’re not there yet.”
http://www.nytimes.com/2006/11/14/s...nce&adxnnlx=1163649608-scF2MlzwvJn+kUNxO1dKvQ
link
https://forums.forteana.org/index.php?threads/the-holocene-impact-working-group.28270/post-674228
 
Incredible meteotsunami phenomenon sees tide surge the wrong way in Welsh harbour.

'We started to see this strange event where the water was surging in and out and in again,' said one Pembrokeshire resident.

Strange tidal behaviour in a Pembrokeshire harbour may have been the result of the rare 'meteotsunami' phenomenon.


Married couple Charles and Claire Davies, whose house overlooks Solva harbour, noticed something odd at around 8.50am on Saturday, when there should still have been around an hour until high tide. "The water appeared to be running out of the harbour rather than in," Charles told WalesOnline. "We started to see this strange event where the water was surging in and out and in again. This happened a number of times over the next quarter of an hour."

The retired engineer, 69, added: "There was a gentle north-easterly wind, the trees were hardly moving, it was a lovely sunny day. We expect surges during storm conditions but we've never seen one during benign conditions. We saw water coming in at seven knots, going back out again and causing boats to lean quite dramatically. It was causing an area of swirling water, a back eddy around the little headland.

"If there were people in the water swimming or in kayaks, it would have been quite a serious event to them, because an Olympic swimmer swims at five or six miles an hour and this water was moving considerably faster than that, I would say. They wouldn't have been able to keep up with it."

Charles said the "extraordinarily powerful" surges died down after about 15 minutes. In his 13 years living in the area, he had never seen anything like it. And there appeared to be no reports of similar activity that morning anywhere other than this small spot of Pembrokeshire coastline
(C) WoL. '22.
 
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The sight of the ash cloud dwarfing the entire islands of Tonga, the fact that internet and comms are down and very little news has come from Tonga yet, the thought of the size of the waves...

It's somewhat surprising that there does not seem to be anticipation of widespread devastation for Tonga? Kind of feels like we should be preparing for some horrendous news from the Pacific in the coming days. No?
What struck me at the time was not that the internet and comms were down, but that a lot of boats still use or have SW and FM radio/transmitters.

A friend of mine does fishing trips from Brighton Marina and he has a SW radio 'just in case'.
 
When Hurricane Sandy hit in 2012, Mr. R and I went outside to check the river, we got to the sidewalk and saw a Tidal Wave rushing down the road straight for us, we ran for the house.
 
When Hurricane Sandy hit in 2012, Mr. R and I went outside to check the river, we got to the sidewalk and saw a Tidal Wave rushing down the road straight for us, we ran for the house.
Was the house unaffected?
 
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