Fierce seas have lifted a 50-tonne concrete block and dumped it on the breakwater at Atlantic french resort St-Jean-de-Luz.
The block, spotted on top of the centre Artha breakwater, was thrown up by waves earlier this week during the violent storms ('Ekaitz' in Bask language) that lashed the length of the Atlantic coast. - above photos Dominique Reis -
An ocean wave "casually" lifted a 50 ton block of
concrete onto one of Saint Jean de Luz town's piers (digue de l'Artha) during Feb 28th's storm photo : Mathieu Mengaillou / Komcébo
Image taken from page 103 of 'La Terre: description des phénomènes de la vie du globe. I. Les Continents. II. L'Ocean, l'Atmosphere, la Vie' -1868-
Saint Jean de Luz bay, scanned marine map (#3647), published in 1878 Survey from 1876 by M. A. Bouquet De La Grye, hydrograph, assisted by M. Favé, student engineer. -courtesy of SHOM old maps-
Note : the Artha dike was not completely built at that time.
extract from 'Plan de la Baie de St Jean de Luz' (Artha massif) Survey in 1873 by Mr A. Bouquet de la Grye full plan on BNF/Gallica
In 1857, Napoleon III approved the construction of three dikes (Sokoa, Artha and Sainte Barbe), which began in 1863. 15 years and 7,400 blocks of 50 tons were needed to raise up the Artha massif (see pictures above), located at depths varying from 6 to 14 m and then again 10 years to build a 250 m long masonry of 32,000 cubic meters.
The final work was completed only in 1895, so more than 30 years after with the Sainte Barbe dike. (see above)
Saint Jean de Luz bay with the GeoGarage platform (SHOM chart)
Pleiades image CNES 2012
Saint-Jean-de-Luz and its characteristic seashell-shaped bay -photo taken by Thomas Pesquet, ISS on January 1st, 2017- credit : ESA/NASA
Saint Jean de Luz/Ciboure bay in winter video : Gaël Duval
Measuring the same size as a small car – the block was thrown about 20m by the waves which came as orange alerts for ‘vagues-submersion’ were in force, The storm waves plus a strong north-westerly current combined to lift the block.
A concrete block of 4 meters long, about 2.5 meters wide and 2 meters thick (20 m3), so a weight of 50 tons !
This phenomenon has already occurred during the storm of December 27/28/29th, 1951 and has not since been renewed : a concrete block was also thrown on to the breakwater – and then washed it off a few days later.
The water on the Earth’s surface was once fresh. How that changed ?
It is estimated there is enough salt in the world’s oceans to cover all the planet’s land surfaces with a layer about 40 stories thick.
But seawater wasn’t always so salty; when the Earth’s oceans first formed about 3.8 billion years ago, as the surface of the planet cooled enough to allow water vapour to liquify, the oceans were mostly fresh water.
So where did all the salt come from?
Satellite view of La Plata River discharge to the Atlantic Ocean.
One way minerals and salts are deposited into the oceans is from outflow from rivers, which drain the landscape, thus causing the oceans to be salty.
It came from rock, laden with elemental salts including sodium, chlorine and potassium, that was spewed forth as magmatic material by massive volcanos from the depths of the planet.
Enter erosion, the process liberating these salts from their rocky prison, thanks to an atmosphere dominated by gases including nitrogen and, importantly, carbon dioxide.
When mixed with water (H2O), carbon dioxide (CO2) can form carbonic acid (H2CO3), a weak but corrosive acid.
This carbonic acid rained down on salt-rich rock, slowly breaking through and releasing the trapped salt into rainwater.
The runoff slowly carried the salt to nearby lakes and rivers, which in turn carried it to the seas.
Although the amount deposited by any one outlet was small, the contribution of millions of outlets over millions of years gradually raised the salinity of the oceans. The process continues.
Along the way from rock to sea, a fair proportion of the salt released from rock is used by living things.
Salt is crucial to both plant and animal life, regulating the amount of fluid in cells and neuron function.
When an organism dies and decomposes, the salt is freed to continue its seaward journey.
The Mariana Arc is part of the Ring of Fire that lies to the north of Guam in the western Pacific.
In 2004, scientists exploring the NW Eifuku volcano near the Mariana Islands reported seeing small white chimneys emitting a cloudy white fluid near the volcano's summit, as well as masses of bubbles rising from the sediment around the chimneys.
In this picture you can see masses of minerals and carbon dioxide escaping from the earth's crust into the ocean.
These vents contribute dissolved minerals to the oceans, which is one reason the oceans are salty.
Acid rain isn’t the only way the seas are fed with salt.
Ongoing volcanism still has an important role to play.
Hydrothermal vents allow seawater that has seeped though the rock of the oceanic crust to return to the surface.
The water is superheated from magma below, and as it travels up it dissolves minerals locked in the crust, erupting as mineral-rich steam.
A similar process involves the interaction of submarine volcanoes with surrounding seawater. Submarine volcanoes are comparable to their above-ground relatives except that their lava cools much more rapidly, allowing for speedy growth.
Magma erupting through submarine fissures boils the surrounding water, which then dissolves salts in the cooling rock to escape in a manner similar to hydrothermal vents.
Many of the worlds islands were formed by this process, releasing thousands of tons of salt in the process.
While seawater contains, on average, about 35 grams of salt per litre, the oceans and seas are not uniformly salty; generally the closer you get to the poles the less saline the water becomes, as fresh water released from the ice of the frozen poles dilutes the concentration of the salt.
When you are swimming in the ocean or sea, the last thing you want is a big mouth full of water.
Its horrible because it is really salty.
But why is it salty?
This video looks into why the sea is salty and how it gets there
There is still one question left: if most of the salt in the sea comes via rivers and streams, why are they not also salty?
The simple explanation is that they do contain salt, but the concentration is much lower, and the salt flows rather than accumulates.
It is estimated that each year four billion tons of dissolved salts are carried to the sea by rivers.
So is the ocean getting saltier?
The answer right now is probably not.
The input of salts is balanced by salts being buried underground by the movement of tectonic plates, the flow of freshwater and a host of other processes.
Global Fishing Watch is using satellite data to monitor suspicious ship activity on the high seas
In many ways, the ocean is the Wild
West.
The distances are vast, the law enforcement agents few and far
between, and the legal jurisdiction often unclear. In this environment,
illegal activity flourishes.
Illegal fishing is so common that experts
estimate as much as a third
of fish sold in the U.S. was fished illegally.
This illegal fishing
decimates the ocean’s already dwindling fish populations and gives rise
to modern slavery, where fishermen are tricked onto vessels and forced to work, sometimes for years.
A new use of data technology aims to help curb these abuses by
shining a light on the high seas.
The technology uses ships’ satellite
signals to detect instances of transshipment, when two vessels meet at
sea to exchange cargo.
As transshipment is a major way illegally caught
fish makes it into the legal supply chain, tracking it could potentially
help stop the practice.
“[Transshipment] really allows people to do something out of sight,” says David Kroodsma, the research program director at Global Fishing Watch,
an online data platform launched by Google in partnership with the
nonprofits Oceana and SkyTruth.
“It’s something that obscures supply
chains. It’s basically being able to do things without any oversight.
And that’s a problem when you’re using a shared resource like the
oceans.”
Patterns of global hotspots of likely transshipping in more detail
Global Fishing Watch analyzed some 21 billion satellite signals
broadcast by ships, which are required to carry transceivers for
collision avoidance, from between 2012 and 2016.
It then used an
artificial intelligence system it created to identify which ships were
refrigerated cargo vessels (known in the industry as “reefers”).
They
then verified this information with fishery registries and other
sources, eventually identifying 794 reefers—90 percent of the world’s
total number of such vessels.
They tracked instances where a reefer and a
fishing vessel were moving at similar speeds in close proximity,
labeling these instances as “likely transshipments,” and also traced
instances where reefers were traveling in a way that indicated a
rendezvous with a fishing vessel, even if no fishing vessel was
present—fishing vessels often turn off their satellite systems when they
don’t want to be seen. All in all there were more than 90,000 likely or
potential transshipments recorded.
Top 10 ports visited by refrigerated cargo vessels likely involved in transshipping.
Even if these encounters were in fact
transshipments, they would not all have been for nefarious purposes.
They may have taken place to refuel or load up on supplies.
But looking
at the patterns of where the potential transshipments happen is
revealing.
Very few are seen close to the coasts of the U.S., Canada and
much of Europe, all places with tight fishery regulations.
There are
hotspots off the coast of Peru and Argentina, all over Africa, and off
the coast of Russia. Some 40 percent of encounters happen in
international waters, far enough off the coast that no country has
jurisdiction.
Korean fishing vessel at sea for more than 500 days.
Track of the Leelawadee (red) and an unnamed fishing vessel (white) rendezvousing in Papua New Guinea waters in July 2015, then again on the Saya de Malha bank in November 2016. - courtesy of SkyTruth -
Chinese fishing vessel at sea for more than 500 days.
The tracked reefers were flying flags from some 40 different
countries.
But that doesn’t necessarily tell us much about where they
really come from.
Nearly half of the reefers tracked were flying “flags
of convenience,” meaning they’re registered in countries other than
where the ship’s owners are from to take advantage of those countries’
lax regulations.
This project wouldn’t have been
possible until quite recently, Kroodsma says.
“Five years ago, there
weren’t enough satellites, and now they’re launching more and more.
And
you need some really big data infrastructure—cloud computing and machine
learning technologies that really didn’t exist in the same scalable,
economical way.”
Machine learning is becoming a powerful and important aspect of analytics workloads.
Amy Unruh and David Kroodsma look at how the Global Fishing Watch project has used Google Cloud Dataflow analytics, Google Cloud Machine Learning, and BigQuery to help monitor and reduce overfishing across the world.
In the process, they show you how you can use Dataflow to transform a data stream for distributed training of a deep neural net on the Cloud Machine Learning platform, and use Cloud Machine Learning's support for hyperparameter tuning to optimize performance of the model.
You'll also learn how you can access trained models for prediction from Cloud Dataflow pipelines, using Cloud Machine Learning's scalable serving, to augment your pipeline's analytical capabilities.
Kroodsma hopes Global Fishing Watch’s data, all of which is
freely available, will be useful to third parties interested in
regulating illegal fishing.
That might include regional fishery
management organizations, researchers and ordinary citizens.
“We’re really empowering others who know more than we do,” he says.
Hopefully, Kroodsma says, this will translate into fewer
illegally caught fish on our plates.
“It’s something that’s no longer
out of sight,” he says.
“People are going to have to account for where
they’re getting their fish.”
NOAA invites public comment on the recently released National Charting Plan.
Comments are due by midnight, June 1, 2017.
The National Charting Plan
is a strategy to improve NOAA nautical chart coverage, products, and
distribution.
It describes the evolving state of marine navigation and
nautical chart production, and outlines actions that will provide the
customer with a suite of products that are more useful, up-to-date, and
safer to navigate with.
It is not a plan for the maintenance of
individual charts, but a strategy to improve all charts.
Since the introduction of electronic navigational charts (ENCs)
thirty years ago, the size of commercial vessels has increased four-fold
and navigation systems have become more sophisticated. Additionally,
there are now over 15 million recreational boat users in the U.S. and
many have joined professional mariners in using electronic chart
displays and NOAA digital chart products when navigating.
User groups of
all types are increasingly expecting more precise, higher resolution
charts, and greater timeliness and ease-of-access to chart updates.
This
plan presents strategies to meet the growing demand.
1025 NOAA raster maps visible in the GeoGarage platform
The National Charting Plan outlines several improvements to chart content, such as:
Reducing unwarranted alarms in the electronic chart display and
information system (ECDIS) used by large commercial vessels and
Improving the differentiation between dangerous and non-dangerous
wrecks.
Resolving uncertainties about ‘reported,’ ‘existence doubtful,’ and ‘position approximate’ dangers.
Creating an orderly layout for ENC charts that will replace the
current set of 1,182 irregularly shaped ENC cells compiled at 131
different scales with a regular gridded framework of cells compiled at a
few dozen standard scale.
Strengthening partnerships with the U.S. Coast Guard by developing
methods to ingest changes to the database of USCG maintained aids to
navigation directly into Coast Survey’s chart production system. This
will save time and avoid any chance of data being entered incorrectly by
hand.
For information on how to provide written comments about this plan, see the Federal Register Notice.
