Monday

We present a unique sunquake with two bounces observed during flare of 6 September 2017 simultaneously with multi-wavelength emission and compare the seismic signatures from the flare of 6 September 2011. We explore some likely scenarios of energy transport in the footpoints with sunquakes supported with EUV, Hα and white light emission. We use a range of parameters derived from the HXR, EUV and Hα line observations to generate hydrodynamic models, which can account for the blue shifts derived from the EUV emission and the red shifts observed with EIS in He II line and by CRISP/SST in Hα line emission. The parameters of hydrodynamic shocks produced by different beams in flaring atmospheres are used as the initial conditions for another type of hydrodynamic models developed for acoustic wave propagation in the solar interior to simulate the sets of acoustic waves produced in the solar interior by the hydrodynamic shocks deposited in different footpoints of magnetic loops. The interpretation of Hα line profiles with large red shifts was carried out by fitting spectral observations to the full NLTE radiative simulations in optically thick transitions (Lyman lines and continuum, Hα, Hβ, Pα) for flaring atmospheres with fast downward motion assuming non-thermal excitation and ionisation by energetic power-law electron beams. The sunquake with a second bounce is found induced by a strong hydrodynamic shock produced by a mixed beam deposited at an angle of -30◦ from the local vertical. The seismic responses in other sources of these two flares are also discussed.