This paper presents an observation of quasi-periodic rapidly-propagating waves observed in the AIA 171/193 Å channels during the impulsive phase of an M1.9 flare occurred on 7 May 2012 .
The instant period was found to decrease from 240 s to 120 s , the speed of the wave fronts was in the range of \sim 664–1416 km s ^ { -1 } .
Almost simultaneously , quasi-periodic bursts with similar instant periods , \sim 70 s and \sim 140 s , occur in the microwave emission and in decimetric type IV , and type III radio bursts , and in the soft X-ray emission .
The magnetic field configuration of the flare site was consistent with a breakout topology , i.e. , a quadrupolar field along with a magnetic null point .
The quasi-periodic rapidly-propagating wavefronts of the EUV emission are interpreted as a fast magnetoacoustic wave train .
The observations suggest that the fast-mode waves are generated during the quasi-periodic magnetic reconnection in the cusp-region above the flare arcade loops .
For the first time , we provide the evidence of a tadpole wavelet signature at about 70–140 s in decimetric ( 245/610 MHz ) radio bursts , along with the direct observation of a coronal fast-mode wave train in EUV .
In addition , at AIA 131/193 Å we observed quasi-periodic EUV disturbances with the periods of 95 s and 240 s propagating downward at the apparent speed of 172–273 km s ^ { -1 } .
The nature of these downward propagating disturbances is not revealed , but they could be connected with magnetoacoustic waves or periodically shrinking loops .