"Surface deformation" refers to changes or alterations that occur on the outer layer of an object or material. It can include things like bending, stretching, or warping of the surface. Full definition
Modeling of surface deformation in volcanic areas: The 1970 — 1972 and 1982 - 1984 crises of Campi Flegrei, Italy. (nature.com)
Only sufficiently thin liquid films undergo significant surface deformations upon exposure to stresses at the surface, while highly regular periodic flow patterns develop in the bulk of thicker films when subjected to the same stresses. (sciencedaily.com)
Michel and colleagues took advantage of the wealth of geophysical data that have been collected in this region, using a catalog of earthquakes that have occurred in the area and models of the fault slip rate inferred from surface deformation given by Global Positioning System (GPS) and satellite observations of ground changes. (seismosoc.org)