A5034204600- Rock Mechanics and Modeling
- earthquake and tectonic studies
- Seismic Imaging and Inversion Techniques
- Drilling and Well Engineering
- Hydraulic Fracturing and Reservoir Analysis
- Geotechnical and Geomechanical Engineering
- Landslides and related hazards
- Seismic Waves and Analysis
- Geophysical Methods and Applications
- High-pressure geophysics and materials
- Geological and Geochemical Analysis
- Seismology and Earthquake Studies
- Hydrocarbon exploration and reservoir analysis
- Earthquake Detection and Analysis
- Geophysical and Geoelectrical Methods
- Tunneling and Rock Mechanics
- Methane Hydrates and Related Phenomena
- Grouting, Rheology, and Soil Mechanics
- Patient Satisfaction in Healthcare
- CO2 Sequestration and Geologic Interactions
- Geological Modeling and Analysis
- Groundwater flow and contamination studies
- Geotechnical Engineering and Underground Structures
- Patient-Provider Communication in Healthcare
- Building materials and conservation
University College London
2016-2025
University College Lahore
2023
Stony Brook University
2018
UCL Australia
2012
University of Toronto
2008
Istituto Nazionale di Geofisica e Vulcanologia
2008
University of Birmingham
2000
Royal College of Surgeons of England
1993-1998
The Honourable Society of Lincoln's Inn
1993-1996
Birkbeck, University of London
1993-1994
The characterization of time‐dependent brittle rock deformation is fundamental to understanding the long‐term evolution and dynamics Earth's crust. chemical influence pore water promotes through stress corrosion cracking that allows rocks deform at stresses far below their short‐term failure strength. Here, we report results from a study creep in water‐saturated samples Darley Dale sandstone (initial porosity, 13%) under triaxial conditions. Results conventional experiments show axial strain...
Abstract The use of hydraulic fracturing to recover shale gas has focused attention on the fundamental fracture properties gas‐bearing shales, but there remains a paucity available experimental data their mechanical and physical properties. Such shales are strongly anisotropic, so that propagation trajectories depend interaction between anisotropic in situ stress field shallow crust. Here we report toughness measurements Mancos determined all three principal orientations: Divider, Short...
We measured acoustic emission energy during antigorite dehydration in a multianvil press from 1.5 to 8.5 gigapascals and 300 degrees 900 C. There was strong signal on dehydration, analysis of recovered samples revealed brittle deformation features associated with high pore-fluid pressures. These results demonstrate that intermediate depth (50 200 kilometers) seismicity can be generated by reactions the subducting slab.
It is usually suggested that thermal cracking in a quartz-bearing rock results from the anomalously high volumetric expansion coefficients of quartz (e.g. Simmons & Cooper 1978). has also been recognized mismatch and mineral anisotropy contribute to materials consist polycrystalline aggregate composed several anisotropic minerals even absence temperature gradient (Friedrich Wong 1986). Experiments investigating rocks commonly involve imaging quantitative stereology crack populations induced...
In the upper crust, chemical influence of pore water promotes time dependent brittle deformation through sub‐critical crack growth. Sub‐critical growth allows rocks to deform and fail at stresses well below their short‐term failure strength, even constant applied stress (“brittle creep”). Here we provide a micromechanical model describing creep water‐saturated under triaxial conditions. Macroscopic is modeled on basis microcrack extension compressive due The incremental strains cracks in...
A new model is presented which can explain the major temporal fluctuations in seismic b-value terms of underlying physical processes time-varying applied stress and crack growth under conditions constant strain rate. The predicts two minima b-value, separated by a temporary maximum inflexion point; corollary being that single broad would be expected scattering attenuation. These are consistent with reported ‘intermediate-term’ ‘short-term’ earthquake precursors period quiescence. We present...
Double torsion tests in ambient air and liquid water have been used to establish critical stress intensity factors (KIc) factor (KI)-crack velocity (v) diagrams for propagation of single tensile cracks Whin Sill dolerite Ralston Intrusive. KIc was 3.28 MN m−3/2 Intrusive 2.58 m−3/2. No corrosion limit encountered.
The characterization of time‐dependent brittle creep, promoted by chemically active pore fluids, is fundamental to our understanding the long‐term evolution and dynamics Earth's crust. Here we report results from a study influence temperature on both short‐term strength creep in three sandstones under triaxial stress conditions. We show that an increase 20° 75°C significantly enhances corrosion cracking all sandstones, leading (1) systematic reduction during constant strain rate experiments...
The elastic moduli of rock in areas susceptible to crack damage, such as within fault zones or volcanic edifices, can be subject large modifications. Knowledge how may vary situations is important for both the reliable modelling volcano deformation and stability linear non-linear models earthquake rupture. Furthermore, it has previously been shown that changes induce stress field surrounding faults. Here we report uniaxial experimental measurements during increasing-amplitude cyclic...
The physical processes generating seismicity within volcanic edifices are highly complex and not fully understood. We report results from a laboratory experiment in which basalt Mount Etna volcano (Italy) was deformed fractured. monitored with an array of transducers around the sample to permit full-waveform capture, location, analysis microseismic events. Rapid post-failure decompression water-filled pore volume damage zone triggered many low-frequency events, analogous long-period...