Definition - What does Isochore mean?
An Isochore is a map which is used to predetermine the drilling depths of wells and locate the structures buried in regions where formations become thinner over certain structural crests. These types of maps are used in stratigraphy, structural geology, volcanology, petroleum geology and sedimentology. Isochores are referred to as the contour lines with equal thickness over a particular area.
Petropedia explains Isochore
Isochore maps are similar to isopach maps due to their thickness; however, isochore maps describe distinct methods for displaying the variations in thickness within a layer. The difference between the two types of thickness maps is that isopach maps exhibit equal thickness in the layers while isopach maps do not. The thickness in isochore maps is measured perpendicular to the boundaries of the layer whereas in isochore maps, it is measured vertically. In geology isochore maps are also referred to as True Vertical Thickness (TVT) maps.