Title About the oil tanker Prestige

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					Title: About the oil tanker “Prestige”
Authors: Javier J. Díez and Pedro Fernández
Affiliation: Universidad Politécnica de Madrid.
Addresses: C/Profesor Aranguren s/n. Madrid 28040. Spain.
Keywords: Emergency safety protocols, potential polluted vessel solutions, crisis
criteria. Organizative structure
Main subject: Safety at sea


On the second half of November, 2002, the oil tanker “Prestige” sank in front of the
continental shelf of the Atlantic Galician coast of Spain, after several days of fighting
against weather. A series of different oil spills provoked during this process and some
time later a large differed black tide. A certain confusion and disorder generated early in
the first days led to a major national political conflict.

The problem is analyzed taking into account four main aspects:
   a) The damage in the vessel and the diagnostic about its evolution.
   b) The type of oil and the knowledge about its behaviour.
   c) The knowledge about the maritime weather and its changes during the operation.
   d) Natural and infrastructural harbour conditions availability.
And with the idea of the necessity of a coordinator institution that can integrate all the
aspects in a management efficiently way.


On November 13th, 2002, the oil tanker “Prestige” broke down with 77,000 tons of fuel
in its tanks. Six days afterwards, the vessel sank into the Atlantic waters at 120 miles
from La Coruña´s coast, reaching 3500 meters depth. That wreck was the beginning of
four main oil spills that reached Galicia´s coast until January and subsequently affecting
Asturias, Cantabria, Basque Country and France. According with the data collected in
the work “Impacto de la marea negra del Prestige sobre las aves marinas”
(SEO/Birdlife, 2003), between November 16th 2002, when the first oil stained bird was
recovered, up to August 31st 2003 , 23181 birds were collected belonging to more than
90 different species: 6,120 birds were alive and 17,061 dead. The most polluted affected
region was Galicia, in the case of polluted birds the amount of cases affected was more
than 50 % of the registered cases in Spain. With 11,802 collected birds, the Common
Guillemot (Uria aalge) has been the most affected species, which means 51 %

With the example of the polluted birds affected we can appreciate the complexity and
the many aspects that can be affected in a disaster like the spill of an oil tank vessel and
even at great distances from the place it sank into the water. Another important aspect is
the necessity of a strategy ready in place for these kinds of events that would minimise
the impact that will occur when the best action solution is assumed.
The disaster and its consequences were instrumented, informatively and politically, as
both a missile and a smog leading to an increasing confusion and delay in decisions. So,
the social and economic measures were adopted with efficiency and on time, but the
technical and organizational decisions on the proper disaster process were insufficient
or suffered strong delays. And the immediately posterior research of the acts and event
has not been scientific or technical but mainly political. The first scientific-technical
Committee with these aims took a month to be created; just to decide what to do with
the two halves of the broken sank vessel and the undetermined oil remaining trapped in

Even under a distant perspective the catastrophe of the “Prestige” may be currently
considered distressing, but it may also be considered as accidental respect to the
Spanish authorities, and the lack of an adequate structure to board it could not be
attributed to any particular authority but to all of them, so that the political answer
should have been to join efforts. Instead, the atmosphere became angrier.

The Accident

On Wednesday November 13th 2002, the oil tanker “Prestige”, with Bahamas flag, sent
a May Day close to Cabo Finisterre (Galicia, Spain). The vessel asked for help to
evacuate the crew due to a high degree list. It transported 77,000 tons of fuel. At 17:00
hours (local time) air inspection from the Spanish authority showed presence of oil from
the vessel in the ocean waters, estimated later in about 4,000 tons. On November 14th
the vessel was towed away from the coast. From that moment, the vessel followed an
erratic route. At first North-West days 14th and 15th, then South, days 15th and 16th, and
finally South West days 17th to 19th. Till the moment the vessel sunk, it dropped about
16,884 tons, and on the moment it sunk and days after about 46,000 tons.

Black tides

The 16th of November the first fuel black tide arrived to the shore, coming from the
first leaked out fuel from the “Prestige”, affecting a coast line of 150 km. in the La
Coruña province, specially in the municipalities of Muxía, Camariñas, Corme, Laxe and
Baldaio, with bad affects in Malpica, Roncudo y Touriñan. The fuel arrived days later
to the Cantabric Coasts. The second big fuel stain arrival occurred on the 29th of
November in Muxía, moving the next days to the south, affecting the Atlantic island
National Park on the 4th of December and the province of Pontevedra on the 6th of
December. The wind changed the track of the oil to the north, and a third arrival of fuel
reached part of the Rias Bajas, Ribeira y La Costa de la Muerte on the 18th of
December. Finally the big mass stain of fuel went to the Cantabric Sea on the 23rd of
December, affecting the North of Spain Communities. A fourth mass of fuel arrived to
the La Costa de La Muerte on January 4th 2003. At that time, less quantity had arrived to
the French coast. Till summer 2003 some small oil episodes were registered in some
places in the coast; and during the whole summer a continuous episode of spots was
registered all along the Galician and Cantabrian coasts. It happened as if a great
reservoir of buoyantly dispersed oil was remaining in the middle of Bizcay Gulf
submitted to successive cyclonic NW to NE summer winds. 743 sandy areas of a total
of 1,064 were affected by the fuel according to the Spanish authority in the International
Oil Pollution Compensation Funds (Comité Científico Asesor. 2003).
    Figure 1. Volunteer students from ETSI Caminos, Canales y Puertos of Madrid.

During several months the black tides affected exclusively Galician Atlantic coasts.
Initially all proceeded from the first great spill in front of the coast and, though it took a
time to cross the few miles because of the veering round winds, Western dominance
ended moving the oils, first to the east and northeast and later to southeast. Fortunately
for Portugal, this spill was so close to shore that the presence of the Galician Atlantic
Islands and the delay of the North component saved its coasts of the oil. Later on,
dragged by SW wind currents, this first spill over passed the north headlands of Ortegal
and Estaca de Bares and progressed, then dragged by more winter wind currents from
W and NW until it reached the more oriental Cantabrian shores. This, supposing that the
black tides which reached French coasts in The Landes could proceed from that first

The second great spill, poured out when the vessel broke in two halves and sank,
delayed more in reaching the coast and most of it had to be mainly moved for a long
time by the Gulf stream; a small part of it, still produced relatively near the surface,
could reach and spread over the Galician shelf being dragged by wind currents towards
Atlantic, and later Cantabrian, coasts; but it had to be scarce enough to not be able to
affect to Portuguese coasts either. The apparently great new affection of the Atlantic
Galician shores had to be mainly due, therefore, to the removal of the oil deposited on
the rocks and cliffs during the first tide.
                   Figure 2. Oil route. Map developed by SASEMAR.

The General Frame of the Sea Disaster Circumstances

One of the principia that the past management of the disaster brought was the lack and
necessity of an organization structure to resolve these crisis situations in an effectible
manner, to put to work all the resources available in time. To the role of the three
Spanish administrations: Local, Autonomic and National, we must add the
inconvenience of a rather deficient international maritime law and organization
structure. Back to the present disaster it can easily lead to confusion with the complexity
and quantity of different technical questions that define the problem: vessel, polluted
load, climate, oceanic circulation, coast morphology, available infrastructures, and
logistic aspects in the saving operations. But it was clear that a general plan
coordinating al least many of the principal aspects never existed and that at least general
and clear conceptual ideas were not taking in account certain elements like the

A damaged vessel will probably break with longer wave length which occurs far from
the coast. Not all the fuels are the same and their characteristics have to be known
immediately, which, for example, can oblige that the vessel never reach an inhabited
area. Also important are the winds and their role in the superficial currents, their relative
importance compared with other currents, the Galicia coast morphology, that offers
many “rías” where a vessel could hypothetically get safer conditions in an emergency
event. The harbour infrastructure prepared or adapted for these events with the
appropriated recovering planning cost would be the beginning of a new discipline
relative to the study of this success, which time to time comes back to the same area
with worse consequences.

That the vessel was not in very good conditions to this kind of traffic along such a
conflictive route was generally supposed from the beginning, and very soon generally
assumed too, and that, as a consequence, the sea rules are clearly insufficient to avoid or
control these accidents. And this question pertains to international politics in such a way
that exceeds any possible scientific or technical discussion; so it is only possible here to
call the attention about it. But any country can adopt immediate measures in the case of
a such disaster when it happens in its territorial waters and the damages are going to
affect mainly, if not exclusively, to its littoral and coastal areas. And they must obey to
decisions taken with the best criteria. To conform these criteria an adequate
management structure must previously exist permitting fast and efficient
communication within the scientific community and between this and the organism of

The Damage of the Vessel and the Diagnostic about its diviner.

The damage was produced in the starboard side of the middle of the vessel hull causing
the immediate pouring of the oil from a couple of its tanks there, though the spilling was
not perceptible on real time because of the atmospheric and oceanic weather conditions.
It happened close to the coast, a few miles from it, under a fine storm from SW veering
round to W and to NW, and for a couple of days the nearly uncontrolled vessel awaited
the decision about its course and, very soon, the arrival of tugs. The decision was finally
imposed by the Spanish Minister who opted for ordering to remove it far away from the
shore taking advantage from a new southern stormy condition.

This decision was surprisingly taken after being consulted several high ministerial
officials, all of them with nautical or naval architecture formation. Therefore all of them
must know that moving the vessel away increased the risk of breaking it because of the
increasing wave length; a wounded vessel in the middle of its length increases its risk of
breaking going out off the continental shelf, and this is fine narrow in Galician and
Portuguese littoral; a previous similar case in the southeaster Mediterranean Spanish
coast close to Almería had been successfully solved in this way, but in the
Mediterranean successive storms are not so frequent, wind wave lengths are rather
shorter and swells are rather less developed, all of those circumstances, among others,
which make less probable to reach the wave conditions for breaking the vessel; besides
other morphological differences in the coastal morphology that we shall consider later.

From this point of view, therefore, it would have seemed more advisable to lead the
vessel to some harboured place on the coast; there are several rías close, though their
availability could be, and it was later, rejected due to both, the necessity of effective
shelter due to the wind wave directions and the necessary depth. Two rías that met both
were La Coruña and Ferrol, with their respective harbour and port facilities;
nevertheless local authorities early and angrily rejected such options, politically making
it nearly unfeasible. Undoubtedly the decision was adopted in a very passionate
atmosphere, but nothing was done on time to try to acquire knowledge of the vessel
characteristics and conditions to accurately evaluate its behaviour and risks before
taking the decision. The information was looked later to assign liabilities.
                Figure 3. North Iberian Peninsula continental platform.

Oil type and the knowledge about its behaviour.

Not all of oils are the same and, in spite of the opacity of the oil business, the accurate
knowledge of one of them is always possible before taking irreversible decisions in a
case of accident like the Prestige’s. In this case, however, the information about the oil
has been deficient a long time, having had many successive data which have been
shown wrong some time later, in such a way that any decision could be easily mistaken.
At the beginning, for instance, it was informed that the proportion of the volatile
fraction was high, what supported the rejection to the entrance of the vessel into the ría
and port of La Coruña, while finally was it was known that the volatility was low, in
agreement with the high density, very similar to the sea water’s. This high density was
the cause of the very low buoyancy shown by the oil of the second spill. Volatility can
be linked to human toxicity, although higher density and viscosity can slow the
reversibility of the destruction of the ecosystem of a ría.

Spreading, miscibility, emulsification, combinability, are proprieties depending of the
composition and nature of the oil and affecting the disturbing behaviour of it, and must
be taken into acoount for any decission about what to do with any accidentedly broken
vessel as the Prestige. And, like in the case of the vessel and the nature of its damage,
the knowledge of the nature and characteristics of the oil was wrong and insufficient,
when it is sure that many scientists could have obtained on time enough good
information to take an appropriate decision. However no adequate informative network
could be used for it.

Knowledge about the sea climate and the sea weather forecasting.

Current winds constitute a major factor in the spreading and breaking up of the oil spill
and in the dragging of both the oil spill and its spots; dispersion is mainly induced
through the turbulence generated by wind waves, while surface and subsurface dragging
is mainly due to the wind currents; and, obviously, current transferences from the wind
are more inertial than wave’s. When the oil spill is still remaining under subsurface,
dragging is due (under a certain depth) to general ocean currents (as Gulf stream) or,
upon a certain height under the sea level, to drift (Coriolis) currents, both much more

Decisions in a disaster like Prestige’s must therefore count on the knowledge of the
current environmental conditions and, particularly the sea climate and weather. As the
main environmental factors in this case, for the maintenance or movements of the vessel
as for the prevision and control of the oil spill dragging and dispersion, depend on the
winds and wind waves, an accurate wind and wind wave forecasting must have been
available from the beginning, immediately after the accident and before taking any
decision about the vessel. Nevertheless news or knowledge about it were missed at all
times, what must be understood as a proof that they were not used in the decision; if
they had been used or even known, they would have been obviously widely divulged.
And it has been evident that the right knowledge of that forecasting throughout the
episode was necessary, and it could have led to different decisions, particularly in
relation with the destination of the vessel, but also for the black tide foresight.

We are afraid too that the behaviour of the different kind of currents in the different
zones of the affected area was also forgotten or, at least, not wholly taken into account.
The Gulf Stream was ignored for a very long time and, if that could be acceptable in
relation with the first oil spill, even in relation with the last one if its oil had been highly
volatile, it could lead to gross mistakes for the foresight and prevention of the black
tides. In fact, the spots of the second great oil spill reached first the shores of the French
peninsula of Brittany, and even the Channel waters, before the shores of the Landes.

              Figure 4. Main currents in winter (left) and in summer (right).
Natural and infrastructural harbour conditions availability.

This is also a main question for the management of all the events of the disaster. It has
been mentioned before the case of a previous event in front of the southeaster Spanish
peninsular coast, when another oil tanker was not allowed to enter for shelter in the
Almería harbour and which was likely considered a precedent; in that case, the vessel
received shelter in Malta harbour, a little farther than Almería. The main reason of the
Spanish authorities then could have been to safeguard the tourist overcrowded beaches
and the Natural Park of Gata Cape; and although Galicia is not so much demanded in its
shoreline, especially as late in the year as in November, its coasts are especially fishery
productive and it has a lot of protected natural estuarine and island coastal areas.

Nevertheless, besides other several important differences between both cases (much less
storm frequency and smaller wind wavelengths in the Mediterranean, more distance to
the coast when accident happened and significant differences in the respective vessel
characteristics and conditions) the different morphology of the coasts is very notorious;
as a matter of fact, Galician are the only irregular coasts in the Iberian Peninsula, with
abundant sheltered areas, though not all of them sufficiently deep for any requirement.
In fact, the accident happened in the surroundings of the ría of Camariñas, where
possibilities of searching one could be tried or studied. Of course artificially harboured
areas in this ría, as in most of Galician, except perhaps that of Vigo, La Coruña and
Ferrol, lack the depth and perhaps the surface extension enough to permit the receiving
a vessel like the Prestige.

                              Figure 5. Ría of Camariñas.
As a matter of fact, actually Camariñas ría is open to the west, the direction of main and
more frequent winds and waves, to which all south winds evolve before to veer round
the north. To reach another greater ría, is necessary to pass in front of one of the two
major capes of the Coast of the Dead, Finisterre to the south or Villano to the north,
wich practically frame that ría and the place where the vessel broke. But finally, near of
both capes, several major and probably suitable rías were available. Southward, nearly
any of the Rías Bajas permit to search sheltered conditions under any weather
conditions, because of their morphology and orientation or the presence of the Atlantic

                                   Figure 6. Galicia.

In fact however most of Rias Bajas open their mouths to SW or W and only the Muros’
open to W-NW, so that a better chance could be offered by the northern Artabrian Rías
Altas. In the Artabrian gulf there are three rías together, La Coruña is open to NW-N
and has a good harbour artificially sheltered versus the NW-N wind waves. Ares is
wider but open also to the SW, and Ferrol is open to the W-SW but it is the widest
totally sheltered natural harbour with complete facilities for vessels. Of course, the
draught of the load and scored vessel did not permit to warrant the success of the
entrance and searching or mooring in any of them, but none objective and dispassionate
analysis seems to have been done, and the decision was rounded of a very passionate

                      Figure 7. Rías of Arosa, Pontevedra and Vigo.


It is very noticeable the complexity and multiplicity of the aspects that were affected in
the disaster of the Prestige, in which the breaking, firstly partially and near to the shore,
and the sinking, when finally the breaking was total in two halves, of the oil tank vessel;
with the consequence of the successive spills; all of which, and even at great distance
from the coast the last, occasioned a tremendous back tide on a extremely long

That a damaged vessel will probably break with more long wave length which occur far
from the coast, and that not all the fuels behave in the same way and suppose the same
type of threat; that the winds, waves and their role in the superficial currents, their
relative importance compared with other currents, and the coast morphology, offer in
Galicia, with so many “rias”, a notorious singularity; that the necessity of some harbour
infrastructure prepared or adapted for these events with the appropriated recovering
planning cost, and of a new discipline relative to the study of these successes, that time
to time comes back to the same area with worse consequences; all of them have become
issues in scientific and even political discussions. But the lack and necessity of an
organization structure to resolve these crisis situations in an effectible manner, to take
advantage on time of all the available resources, appears in our opinion as the main
factor in the problem, and we must trust that the Office created by the Spanish
government can be sufficiently successful. We must add the necessity of radically
improving the international maritime rules.


To the former Commissioned’ Office and current Office for Sea Contamination for their
information and data.


Alvarez Fanjul, E. Establecimiento de un sistema español de Oceanografía operacional.
Puertos. N. 118. pp. 57-64. Madrid. 2004
Comité Científico Asesor, Comisionado para el Prestige. Resumen del informe sobre la
neutralización del pecio. Vicepresidencia del Gobierno de España.
Madrid 2003.
Diez, J. J. Sobre la modernidad y el des”prestigio”. Diario de León, 30.12.02. p.4. 2002.
Caminos, informative bouletin. N. 107. pp. 106-107. UPM. Madrid. 2003.
Laura García, Carlota Viada, Rubén Moreno-Opo, Carles Carboneras, Agustín Alcalde
y Felipe González. Impacto de la marea negra del Prestige sobre las aves marinas.
SEO/Birdlife ISBN: 84-931722-6-X. 2003.

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