  Here we present the first results from ALMA observations of 1 mm polarized
dust emission towards the W43-MM1 high mass star forming clump. We have
detected a highly fragmented filament with source masses ranging from 14Msun to
312Msun, where the largest fragment, source A, is believed to be one of the
most massive in our Galaxy. We found a smooth, ordered, and detailed
polarization pattern throughout the filament which we used to derived magnetic
field morphologies and strengths for 12 out of the 15 fragments detected
ranging from 0.2 to 9 mG. The dynamical equilibrium of each fragment was
evaluated finding that all the fragments are in a super-critical state which is
consistent with previously detected infalling motions towards W43-MM1.
Moreover, there are indications suggesting that the field is being dragged by
gravity as the whole filament is collapsing.
