  On 2005 January 15, the active region AR10720 produced an X1.2 solar flare
that induced high levels of seismicity into the photospheric layers. The
seismic source was detected using helioseismic holography and analysed in
detail in Paper I. Egression power maps at 6 mHz with a 2 mHz bandwidth
revealed a compact acoustic source strongly correlated with the footpoints of
the coronal loop that hosted the flare. We present a magneto-seismic study of
this active region in order to understand, for the first time, the magnetic
topological structure of a coronal field that hosts an acoustically active
solar flare. The accompanying analysis attempts to answer questions such as:
Can the magnetic field act as a barrier and prevent seismic waves from
spreading away from the focus of the sunquake? And, what is the most efficient
magnetic structure that would facilitate the development of a strong seismic
source in the photosphere?
