Abstract The assessment of surface deformation is one of the important aspects for understanding fault activity and disaster mitigation. While near-fault deformation has traditionally been documented using in-situ measurements, advances in optical image correlation now allow high-resolution quantification of both localized and distributed off-fault deformation (OFD) across fault zones. During the 2018 Mw 6.4 Hualien earthquake, rupture of the Milun fault—one of the most active structures in the