  Sunquakes observed in the form of expanding wave ripples on the surface of
the Sun during solar flares represent packets of acoustic waves excited by
flare impacts and traveling through the solar interior. The excitation impacts
strongly correlate with the impulsive flare phase, and are caused by the energy
and momentum transported from the energy release sites. The flare energy is
released in the form of energetic particles, waves, mass motions, and
radiation. However, the exact mechanism of the localized hydrodynamic impacts
which generate sunquakes is unknown. Solving the problem of the sunquake
mechanism will substantially improve our understanding of the flare physics. In
addition, sunquakes offer a unique opportunity for studying the interaction of
acoustic waves with magnetic fields and flows in flaring active regions, and
for developing new approaches to helioseismic acoustic tomography.
