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We report the first unambiguous quasi-periodic large-scaleextreme-ultraviolet (EUV) wave or shock that was detected by the AtmosphericImaging Assembly on board the Solar Dynamics Observatory. During the whip-likeunwinding eruption of a small filament on 2012 April 24, multiple consecutivelarge-scale wavefronts emanating from AR11467 were observed simultaneouslyalong the solar surface and a closed transequatorial loop system. In themeantime, an upward propagating dome-shaped wavefront was also observed, whoseinitial speed and deceleration are about 1392 km/s and 1.78 km/s^2,respectively. Along the solar surface, the quasi-peridoic wavefronts had aperiod of about 163 +/- 21 seconds and propagated at a nearly constant speed of747 +/- 26 km/s; they interacted with active region AR11469 and launched asympathetic upward propagating secondary EUV wave. The wavefronts along theloop system propagated at a speed of 897 km/s, and they were reflected back atthe southern end of the loop system at a similar speed. In addition to thepropagating waves, a standing kink wave was also present in the loop systemsimultaneously. Periodicity analysis reveals that the period of the wavefrontswas consistent with that of the unwinding helical structures of the eruptingfilament. Based on these observational facts, we propose that the observedquasi-periodic EUV wavefronts were most likely excited by the periodicunwinding motion of the filament helical structures. In addition, two differentseismological methods are applied to derive the magnetic field strength of theloop system, and for the first time the reliability of these inversiontechniques are tested with the same magnetic structure.

First Unambiguous Imaging of Large-Scale Quasi-Periodic Extreme-Ultraviolet Wave or Shock