Rock & Ice Physics Laboratory (RIPL)
Department of Earth Sciences
University College London
Last update: July 2018
Geophysics: Developing new techniques to calculate rock physical properties (e.g. strain and damage localisation), using NIR spectroscopy and other remote methods (e.g. InSAR, LiDAR); Analysing the brittle to ductile transition and phase transitions in rocks at high pressure/temperature; Simulating hydraulic fracturing via over-pressurised conduit systems at elevated pressure and temperature.Volcano-Tectonics and associated Geo-Hazards: Integrating high pressure/temperature rock mechanics with field scale physical volcanology to better understand dyke movement and arrest; Plastic deformation and high strain / strain-rate fracture processes; Forecasting failure and failure modes through analysis of the seismic precursors to volcanic-related earthquakes (‘Volcano-Tectonic’, ‘Hybrid’ and ‘Low Frequency’ harmonic events).
|Coupled processes: from dyke
This research examines the fundamental rock physical properties of rock under deformation at elevated pressure and temperatures, with particular focus on fracture and the subsequent coupled Thermal-Hydro-Mechanical processes in volcanic (and related) rocks. These are important as such processes and parameters, particularly mechanical strength, permeability, and their anisotropy, may directly influence the stability of rock masses such as volcanic edifices, as well has having a profound effect on fluid permeability within the fractures and cracks. This is of crucial importance whether for the purposes of estimating rock mass stability, interpreting seismic signals, or for enhanced resource extraction. Central to the success of these strategies is the fundamental knowledge of how hydrofracture proceeds under triaxial deformation in the presence of existing (inherent) crustal stresses, as it is likely that fractures will propagate in preferred directions as a function of the stress field. Although, when taken individually, THM processes are well understood, they have yet to be fully studied as a coupled system in the context of tectonically complex areas where the three principal stresses components are likely to be different. At shallow crustal levels, knowledge of the evolving permeability and porosity via passive means is of crucial importance, yet these methods are qualitative in their nature. At deeper levels, the ductile (plastic) to brittle transition is not fully understood in terms of the seismogenic (Vp, Vs, etc) rock properties - especially when active fluids are considered - and yet these properties are known to be crucial for the evolution of deep earthquake processes such as Episodic Tremor and Slip (e.g. Cascadia). New quantitative methods, validated by experiments, are therefore urgently needed. In addition to their fundamental role in offering a ‘window into the deep Earth’, volcanically active areas are also a source of energy. Globally, 44 TW of power is generated of which it is estimated that 2 TW is accessible. Despite this potential, to date only about 10 GW of installed geothermal generating capacity exists, a utilization rate of just 0.5%. Tapping this resource requires both fundamental understanding of Thermal, Mechanical and Hydraulic (T-H-M) interactions, as well as applied knowledge of how to generate fractures in order to increase production, often through the process of hydraulic fracturing. Although generally well understood in principle, these methods are not fully understood in tectonically complex regimes such as found in and around the edges of the continental margins where much of the geothermal potential exists.
|Simulating passive seismicity in the
The Earth hosts some 600 volcanoes which are known to have erupted in historical time, with nearly 500 million people living on the edifice or nearby. Of these, 40 volcanoes are located in Europe alone, where 2-3 are normally in eruption each year. Some 4-5 million people live within sight of an active European volcano, while at least 10% of the EU population is economically vulnerable to an eruption. Improved understanding of volcanic mechanisms is therefore a central goal in volcano tectonic research and hazard mitigation. Although sophisticated techniques are available for monitoring volcanoes, there is still no universally accepted quantitative physical model for determining whether or not a sequence of precursory phenomena will end in an eruption and for forecasting the time or the type of eruption, whether benign effusive volcanism or devastating and explosive flank collapse. With the advent of modern broadband seismology and GPS, seismicity and ground deformation are the newest types of monitoring technology complementing more traditional geochemical indicators in assessing volcanic unrest. In particular, seismicity due to fluid movement is characterised by low frequency (LF) events, in contrast to high frequency volcano tectonic (VT) earthquakes that are generated by deformation and faulting. In order to link the fundamental micromechanical and petrological processes to these data, this research is focused on the general theme of ‘Laboratory Volcano Tectonics’ with the aim of furthering the understanding of volcano physics by simulating key volcano seismology indicators in a controlled laboratory setting via coupled thermo-hydro-mechanics in volcanic rocks. By comparing this data to published field monitoring and theoretical data, this project is producong results that will contribute to improved methods for investigating short-term precursors before volcanic eruptions.
|Hydro-fracture in the laboratory and its use in linking permeable fracture networks to seismic data
Most crustal rocks are anisotropic. Hydrofracturing is a key process in many areas of pure and applied geosciences, such as the intentional hydraulic fracturing of impermeable rock formations in the hydrocarbon and geothermal energy industries. This new project investigates the dependence and fracture mechanics behaviour of the fluid driven mechanical fracture process to assess the competition between permeability and overpressure upon the derived fracture pattern. In addition, new data is being generated to test the link between the measured seismicity and the accuracy of the fracture patters with the aim of calculating the permeability of the fracture network remotely, as well as using the seismicity as a forecasting tool to mitigate risk.
 *Castagna, A., A. Ougier-Simonin, P.M. Benson, J. Browning, R.J. Walker, M. *Fazio, and S. Vinciguerra (2018), Temperature and Pore Pressure Effects on Brittle-Ductile Transition of Comiso Limestone, JGR, In Press.
 Colombero, C., Comina, C., Vinciguerra, S., & Benson, P. M. (2018). Microseismicity of an unstable rock mass: From field monitoring to laboratory testing. Journal of Geophysical Research: Solid Earth, 123. Doi: 10.1002/2017JB014612
 *King, T, P.M. Benson, L. De Siena, and S. Vinciguerra (2018), Investigating the Apparent Seismic Diffusivity of Near-Receiver Geology at Mount St. Helens Volcano, USA, Geosciences, 7(4), 130, doi: 10.3390/geosciences7040130.
 *Harnett, C.E., P.M.Benson, P. Rowley, and M. *Fazio (2018), Fracture and damage localization in volcanic edifice rocks from El Hierro, Stromboli and Tenerife, Nature Sci. Rep., 8, 1942, doi: 10.1038/ s41598-018-20442-w.
 *Gehne, S., and P.M. Benson (2017), Permeability and permeability anisotropy in Crab Orchrd Sandstone: Experimental insights into spatio-temporal effects, Tectonophysics, 712, 589-599.
 *Fazio, M., P.M. Benson and S.V. Vinciguerra (2017), On the generation mechanisms of fluid-driven seismic signals related to volcano-tectonics, Geophys. Res. Lett., 44, 734-742, doi:10.1002/2016GL070919.
 Ghaffari, H.O., W.A. Griffith, and P.M. Benson (2016), Microscopic Evolution of Laboratory Volcanic Hybrid Earthquakes. Nature Sci. Rep., 7, 40560, doi:10.1038/srep40560.
 *Bakker, R., M. *Fazio, P.M. Benson, K-U. Hess and D.B. Dingwell (2016), The propagation and seismicity of dyke injection, new experimental evidence. Geophys. Res. Lett., 43, 1876-1883, doi: 10.1002/2015GL066852
 Ghaffari, H.O., W.A. Griffith, P.M. Benson, K. Xia, and R.P. Young (2016), Observation of the Kibble-Zurek Mechanism in Microscopic Acoustic Crackling Noises. Nature Sci. Rep., 6, doi: 10.1038/srep21210.
 *Bakker, R., E.S. Violay, P.M. Benson, and S.V. Vinciguerra (2015), Ductile flow in sub-volcanic carbonate basement as the main control for edifice stability: new experimental insights. Earth Planet Sci. Lett., 430, 553-541, doi: 10.1016/j.epsl.2015.08.017
 *Kushnir, A., L.A. Kennedy, S. Misra, P.M. Benson, and J.C. White (2014), The mechanical and microstructural behaviour of calcite-dolomite composites: A laboratory investigation. J. Structural Geology, 70, 200-216.
 Benson, P.M., S. Vinciguerra, M.H.B.Nasseri, and R.P. Young (2014), Laboratory simulations of fluid/gas induced micro-earthquakes: application to volcano seismology. Frontiers in Earth Science, 2, 32, doi: 10.3389/feart.2014.00032
 Vallianatos, F., G. Michas, P.M. Benson and P. Sammonds (2013) Natural time analysis of critical phenomena: The case of acoustic emissions in triaxially deformed Etna basalt. Physica. A, 392 (20) 5172 - 5178. doi: 10.1016/j.physa.2013.06.051
 *Zappone, A. and P.M. Benson (2013), Effect of phase transitions on seismic properties of metapelites: new laboratory evidence. Geology. 41(4), 463-466. doi: 10.1130/G33713.1
 Lavallée, Y., P. M. Benson (2013), M.J Heap, K.-U. Hess, A. Flaws, B. Schillinger, P.G.Meredith and D.B. Dingwell, Reconstructing magma failure and the degassing network of dome-building eruptions. Geology. 41(4), 515-518. doi: 10.1130/G33948.1
 *Bruijn, R., A. Bjarne, A. Hirt and P.M. Benson (2013), Decoupling of paramagnetic and ferrimagnetic AMS development during the experimental chemical compaction of illite shale powder. Geophys. J. Int., 192(3), 975-985. doi: 10.1093/gji/ggs086
 Benson, P. M., Y. Lavallée, M.J. Heap, A. Flaws, K.-U. Hess, and D.B. Dingwell (2012), Laboratory simulations of tensile fracture via cyclical magma pressurisation. Earth Planet Sci. Lett. 349, 231-239.
 Nara, Y., Morimoto, K., N. Hiroyoshi, T. Yoneda, K. Kaneko, and P.M. Benson (2012), Influence of relative humidity on fracture toughness of rock: implications for subcritical crack growth. Int. J. Solids and Structures. 49, 2471-2481
 Vallianatos, F., P. M. Benson, P. Meredith and P. Sammonds (2012), Experimental evidence of a non-extensive statistical physics behavior of fracture in triaxially deformed Etna basalt using acoustic emissions. Europhysics Letters. 97, 58002, doi:10.1209/0295-5075/97/58002
 Lavallée, Y., P. M. Benson, M. J. Heap, A. Flaws, K.-U. Hess, and D.B. Dingwell (2011), Volcanic conduit failure as a trigger to magmatic fragmentation. Bulletin of Volcanology. 74, 11-13, doi:10.1007/s00445-011-1544-2
 Harrington, R. M., and P. M. Benson (2011), Analysis of laboratory simulations of volcanic hybrid earthquakes using empirical Green’s functions, J. Geophys. Res., 116, B11303, doi:10.1029/2011JB008373.
 Benson P.M., S. Vinciguerra, P.G. Meredith, and R.P. Young (2010), Spatio-temporal evolution of coupled hydro-mechanical seismicity: A laboratory study, Earth Planet Sci. Lett. 297, 315-323, doi:10.1016/j.epsl.2010.06.33.
 De Rubeis V., S. Vinciguerra, P. Tosi, P. Sbarra and P.M. Benson (2010), Acoustic Emission spectra classification from rock samples of Etna basalt in deformation-decompression laboratory experiments, in synchronization and triggering: from fracture to earthquake processes, pp. 390, Valerio De Rubeis, Zbigniew Czechowski and Roman Teisseyre (Eds.), Geoplanet: Earth and Planetary Sciences Vol. 1, Springer-Verlag, Milan.
 Benson P.M. (2009), Volcano seismicity in the laboratory, in 2010 McGraw-Hill Yearbook of Science & Technology, pp. 407-409, edited by D. Blumel, McGraw-Hill, New York.
 *Ying, W., P. M. Benson, and R. P. Young (2009), Laboratory simulation of fluid-driven seismic sequences in shallow crustal, Geophys. Res. Lett., 36, L20301, doi:10.1029/2009GL040230.
 Nasseri, M.H.B., P.M. Benson, A. Schubnel, and R.P. Young (2009), Common evolution of mechanical and transport properties in thermally cracked Westerly granite at elevated hydrostatic pressure, Pure and Applied Geophysics, doi:10.1007/s00024-009-0485-2.
 Clark, R.A., P.M. Benson, A.J. Carter, and C.A. Guerrero Moreno (2009), Anisotropic P-wave attenuation measured from a multi-azimuth surface seismic reflection survey, Geophysical Prospecting, 57, doi:10.1111/j.1365-2478.2008.00772.x.
 Benson P.M., S. Vinciguerra, P.G. Meredith, and R.P. Young (2008), Laboratory Simulation of Volcano Seismicity**, Science, 322, 249, doi: 10.1126/science.1161927.
 **Highlighted in: Burlini, L., and G. Di Toro (2008), Volcanic Symphony in the Lab. Science, 322, 207
 Townend, E., B.D. Thompson, P.M. Benson, P.G. Meredith, P. Baud and R.P. Young (2008), Imaging compaction band propagation in Dimelstadt sandstone using acoustic emission locations, Geophys. Res. Lett., 35, L15301, doi:10.1029/2008GL034723.
 Benson, P. M., B. D. Thompson, P. G. Meredith, S. Vinciguerra, and R. P. Young (2007), Imaging slow failure in triaxially deformed Etna basalt using 3D acoustic-emission location and X-ray computed tomography, Geophys. Res. Lett., 34, L03303, doi:10.1029/2006GL028721.
 Benson, P. M., P. G. Meredith, and A. Schubnel (2006), Role of void space geometry in permeability evolution in crustal rocks at elevated pressure, J. Geophys. Res., 111, B12203, doi:10.1029/2006JB004309.
 *Jones, S., P.M. Benson, and P. Meredith (2006), Pore fabric anisotropy: testing the equivalent pore concept using magnetic measurements on synthetic voids of known geometry, Geophys. J. Int., 166, 485-492. doi: 10.1111/j.1365-246X.2006.03021.x.
 Vinciguerra, S., C. Trovato, P. Meredith, P.M. Benson, G. De Luca, C. Troise and G. De Natale (2006), The seismic velocity structure of Campi Flegrei caldera (Italy): from the laboratory to the field scale, Pure and Applied Geophysics, 163, Issue 10, 2205-2221. doi: 10.1007/s00024-006-0118-y
 Schubnel, A., P.M. Benson, B.D. Thompson, J.F. Hazzard, and R.P. Young (2006), Quantifying Damage, Saturation and Anisotropy in Cracked Rocks by Inverting Elastic Wave Velocities, Pure and Applied Geophysics, 163, Issue 5-6, 947 - 973, doi:10.1007/s00024-006-0061-y.
 Benson, P.M., A. Schubnel, S. Vinciguerra, C. Trovato, P. Meredith, and R.P. Young (2006), Modeling the permeability evolution of microcracked rocks from elastic wave velocity inversion at elevated isostatic pressure, J. Geophys. Res., 111, B04202, doi:10.1029/2005JB003710.
 Vinciguerra, S., C. Trovato, P. Meredith and P.M. Benson (2005), Relating seismic velocities, thermal cracking and permeability in Mt. Etna and Iceland basalts, Int. J. Rock Mech. Min. Sci., 42, 900-910. doi:10.1016/j.ijrmms.2005.05.022.
 Benson, P.M., P.G. Meredith, E.S. Platzman, and R.E. White (2005), Pore fabric shape anisotropy in porous sandstones and its relation to elastic wave velocity and permeability anisotropy under hydrostatic pressure, Int. J. Rock Mech. Min. Sci., 42, 890-899. doi:10.1016/j.ijrmms.2005.05.003.
 Benson, P.M., P.G. Meredith and E.S. Platzman (2003), Relating pore fabric geometry to acoustic and permeability anisotropy in Crab Orchard Sandstone: A laboratory study using magnetic ferrofluid, Geophys. Res. Lett., 30, No. 19, 1976, doi:10.1029/2003GL017929.
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