"Vertical displacement" refers to the distance or change in position in an up or down direction. It usually involves measuring the difference between the starting point and the new position in a vertical (or height) dimension. Full definition
The accumulated vertical displacement (10 to 20 meters) occurs within seconds as the fault slips, causing a magnitude 8 to 9 earthquake and a series of tsunami waves. (crew.org)
Long cuts allow the sides to move apart further as the strength is reduced in the middle, also allows more vertical displacement. (mechanics.stackexchange.com)
The occurrence of the three earthquakes induced a total of 1.8 meters of vertical displacement in the past 8500 years for a mean uplift rate of 0.21 millimeters per year. (science.sciencemag.org)