Date of Award

2020

Document Type

Open Access Dissertation

Degree Name

Doctor of Philosophy in Geophysics (PhD)

Administrative Home Department

Department of Geological and Mining Engineering and Sciences

Advisor 1

Roohollah Askari

Committee Member 1

Wayne D. Pennington

Committee Member 2

Gregory P. Waite

Committee Member 3

Vijaya V.N. Sriram Malladi

Committee Member 4

Seiji Nakagawa

Abstract

Fractures play an important role in the geological related processes such as hydraulic fracturing, water-water disposal, and volcanic earthquake. Seismic waves can provide useful information from fractures at a relatively low cost. In particular, the acoustic property of fractures containing magmatic or hydrothermal fluids can provide useful information about the fracture size and the fluid composition within the fracture. For instance, in volcanology, the resonant frequency of long-period events that are linked to crack interface waves is used to obtain fluid properties of cracks in magmatic systems. However, in order to rely on seismic data, they should be precisely characterized in advance. Experimental studies are one of the most important resources to describe and understand physical systems. They are even used to validate analytical and numerical methods. In this dissertation, I aim to gain more insight into the crack waves that are slow guided waves in fluid-filled fractures and are characterized by their dispersive and resonating nature. We will develop two experimental setups. Using the first apparatus that employs the photoelasticity technique, we will visualize the stress regime of the fracture due to the motion, transmission, and reflection pattern of the crack wave. Using the second apparatus which is an acoustic data acquisition system, we extend the fracture of two parallel plates to a more complex and realistic fracture by modifying the fracture stiffness, saturated fluid and fracture geometry, and fracture surface roughness. We evaluate the dispersion and resonance properties of the crack waves under different environments. In addition, some present analytical and numerical models will be evaluated.

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