We present G-band and Ca ii H observations of NOAA AR 10930 obtained by Hinode/SOT on 2006 December 6 covering an X6.5 flare .
Local Correlation Tracking ( LCT ) technique was applied to the foreshortening-corrected G-band image series to acquire horizontal proper motions in this complex \beta \gamma \delta active region .
With the continuous high quality , spatial and temporal resolution G-band data , we not only confirm the rapid decay of outer penumbrae and darkening of the central structure near the flaring neutral line , but also unambiguously detect for the first time the enhancement of the sheared Evershed flow ( average horizontal flow speed increased from 330 \pm 3.1 to 403 \pm 4.6 m s ^ { -1 } ) along the neutral line right after the eruptive white-light flare .
Post-flare Ca ii H images indicate that the originally fanning out field lines at the two sides of the neutral line get connected .
Since penumbral structure and Evershed flow are closely related to photospheric magnetic inclination or horizontal field strength , we interpret the rapid changes of sunspot structure and surface flow as the result of flare-induced magnetic restructuring down to the photosphere .
The magnetic fields turn from fanning out to inward connection causing outer penumbrae decay , meanwhile those near the flaring neutral line become more horizontal leading to stronger Evershed flow there .
The inferred enhancement of horizontal magnetic field near the neutral line is consistent with recent magnetic observations and theoretical predictions of flare-invoked photospheric magnetic field change .