  Pressurized fluid injection into underground rocks occurs in applications
like carbon sequestration, hydraulic fracturing, and wastewater disposal, and
may lead to human-induced earthquakes and surface uplift. The fluid injection
raises the pore pressure within the porous rocks, while deforming them, yet
this coupling is not well understood as experimental studies of rocks are
usually limited to postmortem inspection and cannot capture the complete
deformation process in time and space. We investigate injection-induced
deformation of a unique rock-like transparent medium mimicking the deformation
of sandstone, yet under low pressure. By incorporating within this artificial
rock fluorescent microspheres we capture its internal deformation in real time
during the pressurized flow. We then modify the theory of poroelasticity to
model accurately and without any fitting parameters the internal elastic
deformations, hence providing a physical mechanism for the process. Moreover,
our results demonstrate and validate the underling assumptions of the
poroelastic theory for fluid injection in rock-like materials. Our results are
relevant for understanding human-induced earthquakes and injection induced
surface uplift, as they decouple the role of the pressurized flow from the rock
deformation through the poroelastic theory.
