s-100

This video clip will introduce International Hydrographic Organization (IHO)

s-100 purpose and concept.

Marvelous multibeam math

 Fly-through movie over the new lava flows.

The white polygons show the lava flow boundaries.

The bathymetry data are vertically exaggerated two times.

From Schmidt Ocean Institute by Susan G. Merle/SOI

Area of the survey with the GeoGarage platform (NOAA charts)

With the discovery of big plumes and active venting on the seafloor during CTD tow-yo 6 we really hit the jackpot out here on the Mariana back-arc.

 Logistics, Chemistry, Ocean-floor Biology, Volcanoes -

 There are a wide variety of challenges and studies going on aboard FALKOR.

This led to further investigation of the site with the Autonomous Underwater Vehicle (AUV) Sentry.

 Animation showing the Sentry AUV collecting multibeam sonar data

during a dive and then taking photographs of the seafloor.

Credit: Woods Hole Oceanographic Institution.

The result was a beautiful high-resolution bathymetry map and an even more-detailed photographic survey of the seafloor in the area of interest.

Preliminary AUV Sentry multibeam data in the area of low-temperature venting

discovered during CTD tow 6.

Sentry seafloor bathymetry data resolution is 1 meter.

The white box shows the area of the Sentry photo survey that captured the new lava flows.

To our surprise, the photo survey discovered a very young lava flow in the area where the CTD tow-yo indicated low-temperature venting.
This led us to question: when was that eruption, and how big was it?

Maps showing the 2 ship multibeam bathymetry surveys in the area of the newly-discovered lava flows.

The data on the left were collected in 2013, the data on the right in 2015.

The black polygons are the new lava flows. Numbers on the 2015 map specify the maximum thickness of each lava flow in meters.

The white box shows the area of the Sentry bathymetry survey.

Doing the Math

This is where mapping we have done with R/V Falkor’s multibeam sonar came into play.
Sonar systems send sound pulses from the ship to the seafloor (called “pings”).
Present-day sonar systems can provide up to 432 individual depth readings (“soundings” or “beams”) across each ping - this is where the term “multibeam” gets its name.
The amount of time it takes each sound pulse to return to the ship indicates the depth beneath the ship: the longer it takes the sound to return, the deeper the water.
Those depth soundings are pulled together to create a grid of the seafloor.
Ship-acquired seafloor depth information is scarce and expensive to acquire, so whenever the opportunity presents itself scientists will collect sonar data - even if they have no plans to use it for their individual research.
One aspect of my job is to compile all the ship sonar data collected in the areas where we work and pull it together into a database.
Because of this, we have with us the multibeam sonar data collected on a previous cruise to this area in 2013 (by Patrick Shore and Doug Wiens on R/V Melville), and we’ve resurveyed the same area during this expedition.
By performing a little bit of math, we can calculate the difference in the seafloor depths between then and now.
The earlier grid (2013) is subtracted from the new data (2015) and depth differences in those grids show changes in the seafloor between now and then.

The Results

Surface differencing is a quick way to show us where the new lava erupted on the seafloor, and we can also calculate the volume of new lava flows.
The results reveal that the new lava flows extend over 7 kilometers from north of south, and that greater than 60,000,000 cubic meters of lava was deposited on the seafloor.
The northernmost lava flow was the largest, with a volume of over 20,000,000 cubic meters, piling up pillow lavas over 125 meters (400 feet) thick.
Now that’s the kind of math that I find incredibly exciting!  

Spanish galleon may contain biggest treasure haul ever found on seabed

"Holy grail" of shipwrecks found off Colombia

World's largest sunken treasure? 
other video

From The Guardian

Gold and jewels on board Spanish ship the San José that sank 300 years ago off Colombia could be worth billions
The wreck of a Spanish galleon laden with treasure has been found 300 years after it was sunk by the British, sparking speculation that it contains the most valuable haul ever found on the seabed.

Oil painting by Samuel Scott depicting the action off Cartagena, 28 May 1708 

The Colombian president, Juan Manuel Santos, announced the find and said a museum would be built to display the artefacts, which are thought to include gold, coins, silver, emeralds and other gems and jewellery and the personal wealth of the viceroy of Peru.

The ship, the San Jose, has been described as the holy grail of shipwrecks, carrying one of the richest treasure cargos ever to have been lost at sea.
The treasure was collected in the South American colonies to be shipped to Spain to help fund King Philip V’s war of succession against the British.
Santos said the treasure was now worth at least £662m, although other estimates have said it could run into billions.

 courtesy of El Pais

The ship was sunk in 1708 in the Caribbean Sea close to the walled port city of Cartagena during heavy fighting with the British.
A team of international experts, the Colombian navy and the country’s archaeology institute discovered the wreck last week near the island of Baru.

  Location of the shipwreck with the GeoGarage platform (CIOH charts)

Dr. Carla Rahn Phillips' estimation (inside the polygon) of the location of the Galeon San Jose
 - off Cartagena, Colombia (OSRI)
 In a follow-up statement, the presidency said the shipwreck was discovered
at a site “never mentioned in previous studies.”
The fate of the treasure has been the subject of a long-running legal battle with U.S.-based
Sea Search Armada, which claims its predecessor found the wreckage in 1981.
SSA has been claiming billions of dollars for breach of contract from the Colombian government, but in 2011 an American court ruled that the galleon was the property of the Colombian state.
 

zoom on the area with the GeoGarage platform (CIOH nautical charts)
English Commodore Charles Wager tracked down the treasure-laden ship

25km (16 miles) off Cartagena and it sank in 200-300m of water.
In the fighting the vessel was reported to have exploded, with most of its crew killed.

The president tweeted: “Great news! We have found the San Jose galleon.”
Later he went on television from Cartagena’s naval base and said: “Without a doubt, we have found, 307 years after it sank, the San Jose galleon. We will build a great museum here in Cartagena.”
He said the find “constitutes one of the greatest – if not the biggest, as some say – findings and identification of underwater heritage in the history of humanity.”

 The remains of the Spanish galleon San Jose,

which sunk off the Caribbean coast of Cartagena de Indias, Colombia

 courtesy of Ministerio de la Cultura de Colombia

Ownership of the ship’s treasure has been the subject of a long-running legal dispute.
In 1981 an American-based salvage company, Sea Search Armada, said it had located the area where the ship sank.

Sidescan sonar view

The company and the government agreed to split any proceeds, but the government later said all treasure would belong to Colombia, a view that was backed by a US court in 2011.
The supreme court ruled that Colombia held the rights to items deemed to be “national cultural patrimony”.
Anything else would be halved between the salvage company and Colombia.

Sonar images have revealed bronze cannon made specifically for the ship, arms, ceramics and other artefacts, said the president.
The 150ft long ship with a beam of 45ft was armed with 64 guns.
Some 600 people went down with the vessel after it exploded when hit by fire from a British warship.
The wreck falls within the UN’s definition of an underwater cultural heritage site.
Archaeological excavation and scientific tests will continue to ensure it can be properly preserved, said the president.

 Routes of the Spanish galeons

The San Jose was part of a Spanish fleet that sailed to the Americas to load up with gold, silver, emeralds and other precious stones and metals.
The British sought to capture them as a way to cut off Spain’s war finances.
Commodore Charles Wager, in command of four British ships including HMS Expedition, attacked the fleet off the island of Baru.
His plan had been to attack the largest ship, the San Jose, and take control of the crew and cargo.
However, as it was about to be captured it blew up and sank.
Wager described the close quarters broadsides, and said the San Jose exploded with such intensity that he could feel the heat from his own ship.
“I believe the ship’s side blew out, for she caused a sea that came in our ports,” he wrote.
“She immediately sank with all her riches.”

It is estimated that the San Jose is one of more than 1,000 galleons and merchant ships that sank along Colombia’s coral reefs over more than three centuries of colonial rule.

Links :

• NPR : Wreck Of Legendary Spanish Galleon Is Finally Found, Colombia Says
• The Old salt blog : Galleon San Jose, the “Holy Grail of Ship Wrecks”
• The City paper : The ‘rich’ history of the San José
• YouTube : INNAH, El galeón San José, la historia presente
• ABS.es : Lo que los arqueólogos descubren en las fotos del galeón San José 
• Book : The Treasure of the San José: Death at Sea in the War of the Spanish Succession (Carla Rahn Philips)

Why we sail - a film about the Volvo Ocean Race

Follow seven international teams as they race 38,739 nautical miles around the world in the 12th edition of the Volvo Ocean Race.
Along with being the foremost offshore sailing competition, the race reminds us about the vastness of our Oceans and what it means to be a modern day explorer.

All those confusing geography terms, explained in a gorgeous antique map

This impressive imaginary map

manages to define many geographical terms without needing text.

David Rumsey Collection  : a chart of geographical definitions.

From Vox by Phil Edwards

You can see the original map, circa 1870, at the David Rumsey Collection (we've upped the contrast on this digital version to make it slightly more readable).
A few of the more confusing terms merit some clarification, so we referred to the Oxford English Dictionary on the following:

• What's the difference between a gulf and a bay? They're pretty similar, but a bay is often wider and has a wider opening to the sea. At the same time, some gulfs are larger than many bays (like the Gulf of Mexico). There's bound to be some confusion, since the terms are often used interchangeably.
• A cascade is a small waterfall.
• Channel versus strait versus passage versus sound? A channel and strait both connect bodies of water, but a channel is often wider. A sound is like a strait, but larger. A passage typically connects bodies of water between islands. However, the terms are often used interchangeably.
• In case it wasn't clear, a cove is a sheltered recess in a mountain.

Now that you finally know what some of those half-remembered terms mean, the next step is obvious: Go out and see some in person.

Links :

• GeoGarage : Rumsey historical collection upon Google Maps imagery