The phrase "subsurface structure" is correct and commonly used in written English.
It refers to any underlying physical or geological features that are underneath the surface of something. Example: The engineers needed to conduct a thorough analysis of the subsurface structure before beginning construction on the new building.
Structural characteristics of subsurface structure can be evaluated by a dimensionality index.
However, geophysical studies enable to highlight structural features and understand the subsurface structure in such areas.
Putzig, N. E. et al. Subsurface structure of Planum Boreum from Mars Reconnaissance Orbiter Shallow Radar soundings.
Seismographs record the amplitude and frequency of seismic waves and yield information about the Earth and its subsurface structure.
Hammond, N. P., Phillips, C. B., Nimmo, F. & Kattenhorn, S. A. Flexure on Dione: investigating subsurface structure and thermal history.
One of the first to suggest using explosives for studying subsurface structure, he established across Russia a chain of seismic stations that continue in operation.
Surface and subsurface structure and chemistry has been investigated by SEM/FIB and XPS.
Conybeare contributed to the elucidation of the geology of Ireland and was also one of the first to use geologic cross sections to express subsurface structure.
Air guns produce an acoustic shock wave that propagates through rock and is reflected back; the return signal is analyzed for clues to the subsurface structure, including the presence of hydrocarbon deposits.
Additional investigations of the subsurface structure were performed by means of focussed ion beam cross-sections.
In the journal Science Advances, an international team of researchers from North Korea, China, the United States and Britain published the first-ever survey of the volcano's subsurface structure.
