Thanks for your informed comments, auv-ee!
This has probably been answered before, but does anyone know roughly the 'resolution' of the detectors being used? I.e., how small a piece of metal is still likely to be detected?
Reverting briefly to the acoustic detection a year ago, I wonder what effect that tall ridge (running northwest) to the north of the new search area would have on a pinger lying on the ocean floor. If the submarine was to the south of it and the pinger north of the ridge, would the ridge tend to block the sound from it, or would the ridge in fact help deflect the sound upwards to where the submarine was? Just an idle thought I had, knowing nothing of underwater acoustics.