atquake

Eathquake musings

MH 370

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It’s hard not to get sucked into the Maylasian 370 story at some level… Although I mostly work on earthquakes, I started out and still am a sonar and seafloor mapping guy, so am interested in how it will be to search for this airplane.  The pinger contacts were on the west flank of Wallaby Ridge, also known as the Zenith Plateau.  Unfortunately this is a very rough area of seafloor that has never been mapped, much like most of the worlds oceans.  When you look on Google Earth, you get the impression that the ocean floor has been mapped everywhere, and in a way that is sort of true.  The Google earth image comes from Satellite altimetry, mapping the ocean surface.  Oddly, there is topography on the surface of the ocean caused by the gravitational pull of the seafloor mountains and trenches below. So mapping the surface gives you a sort of “pseudo gravity” map, which can then be converted to bathymetry with enough ground truth.  It looks great from a distance, but up close, you see that the smooth rolling hilly topography isn’t real, it’s mostly noise from the low resolution of the data.  Real mapping of the seafloor requires ships and underwater vehicles, and is very, very slow (and expensive) which is why it hasn’t been done globally.

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The pinger contacts from MH370 still leave a large area to search, but at least it’s possible, where without them, it was nearly hopeless.  The problem now is that the terrain there is very rough.  Even though it’s ~ 100 million years old, it has very little sediment cover, a few 10’s of meters most likely, of microfossil “ooze”.  the few swaths of multibeam sonar data nearby show a very rough terrain that will make finding even an intact airplane difficult, and there’s not much chance it’s intact.  A landing like the “miracle on the Hudson” might have been possible in perfect weather and a good pilot, but more likely the airplane is in small pieces.  Finding such pieces in a background of a mountainous, hard, rough, rocky bottom is a sonarmans nightmare.  There isn’t much contrast between the metal and the rocks from the sonar’s eye, and so you’d have to hope for a big recognizable piece to appear, like a wing.  If not, they will likely be chasing many many possible targets, and trying to photograph them with the AUV cameras, or with ROV cameras.  Hopefully they will get more vehicles there, as the one small AUV has a huge job.

One of the strangest stories in aviation history may take months, or even years to be told, but I think it will be told.

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Written by eqgold

April 16, 2014 at 9:25 pm

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