  The solar flare on July 30, 2011 was of a modest X-ray class (M9.3), but it
made a strong photospheric impact and produced a "sunquake," observed with the
Helioseismic and Magnetic Imager (HMI) on NASA's Solar Dynamics Observatory
(SDO). In addition to the helioseismic waves (also observed with the SDO/AIA
instrument), the flare caused a large expanding area of white-light emission
and was accompanied by substantial restructuring of magnetic fields, leading to
the rapid formation of a sunspot structure in the flare region. The flare
produced no significant hard X-ray emission and no coronal mass ejection. This
indicates that the flare energy release was mostly confined to the lower
atmosphere. The absence of significant coronal mass ejection rules out magnetic
rope eruption as a mechanism of helioseismic waves. We discuss the connectivity
of the flare energy release with the electric currents dynamics and show the
potential importance of high-speed plasma flows in the lower solar atmosphere
during the flare energy release.
