Synthetic materials are used to cast sheet-like, porous test specimens that have strongly-bonded layers with contrasting mechanical properties. The layered specimen is placed between two thick, transparent plates and constant, anisotropic far-field stresses are applied to the specimen. Fracturing fluid is injected in the center of the specimen, and the induced hydraulic fracture propagation is captured with high-resolution digital images and subsequent image processing. Displacement of the specimen body around the growing fracture is resolved using Digital Image Correlation (DIC) analyses. Discrete Fourier Transform (DFT) is applied to smooth displacement data. The smoothed displacement data is subsequently used to quantify hydraulic fracture width in various spatial positions along fracture length and to quantify strain deformations around the fracture. First, we show the deformation profiles around a hydraulic fracture induced in a homogeneous test specimen. Then, we demonstrate displacement and strain profiles around a fracture induced across three-layer specimens. The displacement and strain are shown to be highest at the center of the specimen where fluid is injected and hydraulic fracture is initiated. The displacement and strain decrease gradually along the length of the fracture away from the middle of the fracture. For specimens that have soft-middle layer bounded by hard layers, the rate of change in displacement along fracture length becomes markedly lower in the bounding-hard layers. By contrast, the rate of change in displacement is rather uniform across the layers for specimens that have hard-middle layer bounded by soft layers. In some instances, there is a clear asymmetry in measured strain on opposite sides of the fracture where one side of the fracture is strained and the other side has zero strain. This research presents novel experimental methods that, for the first time, enabled visualizing and quantifying the deformation of multi-material rocks as hydraulic fractures propagate through them. Fundamental insights are presented on how individual layers in layered test specimens with contrasting mechanical properties deform for different combinations of layer properties. 1. INTRODUCTION In AlTammar et al. (2019), we developed a fracture cell and experimental methods to investigate hydraulic fracture propagation across multiple materials with contrasting mechanical properties. A series of hydraulic fracturing experiments were performed in porous, layered test specimens. Figure 1 shows schematics of the fracture cell used to perform the experiments. The test specimen is a thin sheet of cast materials placed between two transparent plates. The test specimens are made of mixtures of plaster, talc and hydrostone in varying proportions to control the strength of the material. The mechanical properties for a wide range of mixtures were measured to establish a specified contrast in Young's modulus ( E ) and fracture toughness ( K IC ) when preparing the layered test specimens. The specimen is 6 by 6 inches and the monitored field of view during the tests is about 4 inches by 2 inches. A random speckle pattern is painted on the specimen using white and black spray paint. A far-field stress is applied on two parallel sides of the specimen in the x-direction (Figure 1c) and glycerin is injected at the center of the specimen to induce a fracture. The fracturing process is recorded using a high-resolution digital camera at 30 frames per second. Lastly, key frames of fracture propagation are obtained from the recorded video and the frames were analyzed using a Digital Image Correlation (DIC) software to resolve full-field displacement and strain as the fracture grows through the specimen. Figure 1d shows a cast three-layer specimen made in the laboratory. Details of the experimental methods are given in AlTammar et al. (2019).