The size and location of an oil seep in the Gulf of Mexico indicates that it could be caused by human activity.

New Orleans, LA – While oil giant BP has successfully settled in the first of a three-phase trial for at least $7.8bn, residents of the Gulf Coast remain concerned about a large oil seep along an area near BP’s capped Macondo well.

The disaster at BP’s well gushed at least 4.9 million barrels of oil into the Gulf of Mexico during the spring and summer of 2010, causing the largest marine oil disaster in US history. By comparison, the Macondo reservoir, from which this new oil is likely seeping, contains an estimated 50 million barrels of producible oil.

Al Jazeera conducted a flight over the area on February 29, 2012, and found silvery oil sheen, oil globules and long reddish rope-formed oil across an area 35 km long with a width ranging from 20 to 100 metres. Al Jazeera noticed oil seeping from this same site during a fly-over on September 11, 2011.

While natural oil seeps are common in the Gulf of Mexico, the size and location of this seep could indicate that it has been caused by human activity.

1) A retired career physicist with NASA, Bonny Schumaker, now the owner and pilot of On Wings of Care, has logged more than 500 hours surveying the area of the oil seep in question [Erika Blumenfeld/Al Jazeera]

2) Since August 2011, Schumaker has found a consistent, approximately 35km-long crescent-shaped slick of oil in an area 19 kilometers northeast of BP’s Macondo well [Erika Blumenfeld/Al Jazeera]

3) From afar, the oil and oil sheen appear as wind patterns atop the water surface, but as one nears the slick, silvery sheen and rainbow colours and the oil smell make clear what it is [Erika Blumenfeld/Al Jazeera] 4) While several dolphins and a sea turtle were visible in the area, Schumaker was concerned by the overall lack of visible wildlife, in an area that should normally be full of marine creatures [Erika Blumenfeld/Al Jazeera] 5) Edward Overton, professor emeritus at Louisiana State University’s environmental sciences department, examined data from oil samples taken from this area last September and confirmed that the oil is from the Macondo reservoir [Erika Blumenfeld/Al Jazeera] 6) Experts believe the oil is likely to have come from a seep in the seabed, but there is debate about what caused the seep, as many believe it may well have been caused by the blowout of the Macondo well and the failed attempts to cap it during Spring 2010 [Erika Blumenfeld/Al Jazeera] 7) Dr Ira Leifer, a University of California scientist who is an expert on natural hydrocarbon oil and gas emissions from the seabed, told Al Jazeera, “Because of the size and its location, there is a greater concern that should require a larger public investigation” [Erika Blumenfeld/Al Jazeera] 8) While BP and the Coast Guard have confirmed BP’s cap on the Macondo well is not the source of this oil, the broader question posed by experts is whether the oil giant’s actions while sealing the well could have caused this seep [Erika Blumenfeld/Al Jazeera] 9) Dr Leifer’s concerns are that if the seep increases in volume, “it could be a persistent, significant, continuous oil spill again, and that would require BP to go back and re-drill, and block off the pipeline even deeper than they already did, or else they would be liable for whatever the emissions are, forever, because it’s not going to stop for a very long time” [Erika Blumenfeld/Al Jazeera] 10) New Orleans attorney Stuart Smith, who litigates against major oil companies, believes the burden of proof on the oil’s origins lies with BP. “Our worst fears have proven true. We have a chronic leak scenario caused by the Macondo well, and it is time for the Feds and BP to come clean and tell the American public the truth. Unless/until the government and BP explain in a verifiable manner what the source of this oil is, in my opinion any thoughts of settlement are way premature” [Erika Blumenfeld/Al Jazeera]

Follow Erika Blumenfeld on Twitter: @ErikaBlumenfeld