Development of the emerging bipoles and magnetic cancelation in the eruption region by HMI magnetograms (panels a) − h)) and the magnetic flux evolution (panel i)) for the box region in panel h), in which the contour of F1 is also superposed. The box in panel a) indicates the field of view (FOV) of panels b) − c), in which the boxes show the FOV of panels d) − h). The boxes in panels d) − g) indicate the cancelation region of the magnetic flux. The vertical line points out the eruption time.