English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Zendy Plus

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Zendy Tools

Zendy Open

Exploration geophysics, forecasting of geo-hazards and geodynamic studies require the improvement of geophysical methods for subsurface imaging. The better the physical properties of the geomaterials are constrained the higher is the accuracy of the subsurface model. Physical properties of geomaterials are correctly defined not only when elastic parameters are precisely evaluated, but also when the correct rheological model is considered (e.g. frequency dependent moduli). For instance, imaging of crustal domains is more accurate when viscoelasticity is taken into account. This is especially true when the subsurface domains are impregnated with liquids such as water, hydrocarbons or magma. Attenuation and dynamic moduli are the parameters required to define material viscoelasticity. Presently they are little investigated in the range of the seismic frequencies. Viscoelasticity of few lithologies has been measured and only at limited physical conditions. In addition, the role of fluids in enhancing viscoelasticity is still poorly understood, and a unified theory explaining how fluids interplay with seismic waves, generating attenuation, does not still exist. The research presented in this thesis aims to improve our understanding of physical properties of geomaterials. The thesis is divided into three parts with specific goals. The first goal of this research was to design, build and calibrate a new experimental machine capable to measure seismic wave attenuation for frequency ranging from 0.1 to 100 Hz: the “Broad Band Attenuation Vessel” (BBAV). This instrument measures seismic wave attenuation in decimetric-sized samples at confining pressures up to 25 MPa. In addition, the peculiarities of the BBAV had allowed developing a methodology to measure fluid pressure transients as a consequence of a variation of vertical stress in a partially saturated sample.

repository for publications and research data (eth zurich)

Experimental characterization of reservoir rocks and geotechnical materials: Low frequency attenuation, ultrasonic velocities and local pore pressure effects