We present a multiwavelength study of the formation and ejection of a plasma blob and associated extreme ultraviolet ( EUV ) waves in active region ( AR ) NOAA 11176 , observed by SDO/AIA and STEREO on 25 March 2011 .
The EUV images observed with the AIA instrument clearly show the formation and ejection of a plasma blob from the lower atmosphere of the Sun at \sim 9 min prior to the onset of the M1.0 flare .
This onset of the M-class flare happened at the site of the blob formation , while the blob was rising in a parabolic path with an average speed of \sim 300 km s ^ { -1 } .
The blob also showed twisting and de-twisting motion in the lower corona , and the blob speed varied from \sim 10-540 km s ^ { -1 } .
The faster and slower EUV wavefronts were observed in front of the plasma blob during its impulsive acceleration phase .
The faster EUV wave propagated with a speed of \sim 785 to 1020 km s ^ { -1 } , whereas the slower wavefront speed varied in between \sim 245 and 465 km s ^ { -1 } .
The timing and speed of the faster wave match the shock speed estimated from the drift rate of the associated type II radio burst .
The faster wave experiences a reflection by the nearby AR NOAA 11177 .
In addition , secondary waves were observed ( only in the 171 Å channel ) , when the primary fast wave and plasma blob impacted the funnel-shaped coronal loops .
The Helioseismic Magnetic Imager ( HMI ) magnetograms revealed the continuous emergence of new magnetic flux along with shear flows at the site of the blob formation .
It is inferred that the emergence of twisted magnetic fields in the form of arch-filaments/ “ anemone-type ” loops is the likely cause for the plasma blob formation and associated eruption along with the triggering of M-class flare .
Furthermore , the faster EUV wave formed ahead of the blob shows the signature of fast-mode MHD wave , whereas the slower wave seems to be generated by the field line compression by the plasma blob .
The secondary wave trains originated from the funnel-shaped loops are probably the fast magnetoacoustic waves .