The little Mole Hill that is really a Mountain
by BK Lim, Geohazards Specialist
(6 Sept 2010, firstname.lastname@example.org).
Very often we make a mountain out of a mole hill, but in the BP’s Macondo bathymetry, it is just the opposite. The reasons for this willful negligence are already given in previous articles. This posting is to illustrate why we do not get it right when looking at things from the wrong perspective.
Figure 116-1 shows the satellite image of the domes surrounding the Macondo site. The rectangular box (5 x 6 km) is the outline of the Macondo site. You will see that wells A, B and S20BC are all concentrated on the tiny red dot at the middle of a convex edge of the “L-shaped” escarpment which is approximately 12 km by 5.5 km.
There are probably some good geological reasons for this odd shape “low rise (BP’s assessment)” escarpment but that is the subject matter for future discussion. Even from the reconnaissance satellite image, the terrain can be seen to slope down from the point marked X. Whether we call this a cone, dome or just plain escarpment is immaterial, since the whole “escarpment” is by itself a raised landform. Raised landform is either “the seafloor manifestation of some underlying geological events or continuing processes” or “a product of erosion where the underlying formation is more resistant than the surrounding”. However the former is more likely given a number of tell tale features.
It is easy to dismiss this “escarpment” as insignificant, given its smaller extent and lower relief than its adjacent giant neighbours; Whiting Dome, Gloria Dome and Michell Dome. But a “mound” with a radius of 3 to 4.5 km and a height exceeding 500 ft (150m) is not insignificant by most geohazards assessment standards. The worst possible well location could not have been chosen for Well A, Well B and S20BC, even on the basis of this satellite imagery reconnaissance.
In my opinion, the erroneous and fraudulent Macondo bathymetry had a terribly misleading effect. Anyone looking at the highly smoothened Macondo bathymetry would be inclined to think that well A, Well B and S20BC were located on a gentle uniform slope. But the “smoothened seafloor morphology” belies the apparent sharp transition from sloping to flat seafloor, the distinct convex outline of the base of the escarpment and the 3º general slope.
Figure 116-2 shows the satellite image background with the superimposed Macondo bathymetry. The discrepancies are startling even to the untrained eyes. The dark blue shadows conjure an image of an irregular raised landform, possibly faulted close to the seafloor. An MBES (multi-beam echo sounder) image acquired at 50 m above the seabed would have yielded a lot of seabed features (not featureless as asserted by BP) that could have averted the terrible Oil Spill Disaster. This disaster need not have happened. It could have been easily averted given due diligence in the geohazards assessment.