Usu volcano started to erupt on March 31, 2000. The Geographical Survey Institute (GSI) repetitively monitored the surface displacement in and around Usu volcano by digital photogrammetric method using stereo aerial photos. The advantage of this method is that it can map the spatial distribution of deformation even in the area where instruments commonly used such as GPS cannot be applied. As a result of the analysis, it was found that; before the eruption of March 31, the uplifted area was concentrated around the cinder cone of Usu volcano. After the eruption began, the uplifted area shifted to Konpira-yama and Nishi-yama area. After April 3, the uplifted area was limited in the area around Nishi-yama.
