Earth and Environmental Sciences (SEES)

Profile

Academic Duties

• Director of the rock mechanics laboratory, School of Earth and Environment
• Teaching, Undergraduate and Postgraduate
• Supervision of Masters and PhD students
• Basic research
• External reviewer for numerous scholarly journals and funding bodies, both national and international.

Research interests/supervision opportunities

I specialise in the relatively new discipline of Rock Physics, but with broad and cross disciplinary research interests in areas as diverse as geophysics, volcano-tectonics, and structural geology. My  particular focus is to apply modern laboratory rock deformation techniques to simulate active tectonic areas such as deep subduction zones and active volcanoes, recording the induced seismicity that acts as a diagnostic to these deep crustal processes. Current research builds on the synergy created by the new generation of rock deformation methods and laboratory acoustic emission (microseismicity) instruments by investigating such coupled processes in detail, and how these interact with both plastic and brittle crustal deformation ranging from attenuation and reservoir induced seismicity in the applied geosciences to fundamental questions in volcano-tectonics and earthquake triggering.

For example, seismicity and ground deformation are the short-term precursory phenomena most frequently detected before a volcanic eruption, and to a lesser extent earthquakes, occurring as the Earth's crust is distorted by magma pushing its way to the surface, and as fluids (magma, volcanic gas and/or hydrothermal fluids) move within faulted rock. The final approach to eruption is commonly preceded by accelerating rates in both the occurrence-rate of low magnitude volcano-tectonic (VT) earthquakes and of low-frequency (LF) and very-low-frequency (VLF) events. And, although there are many examples of areas exhibiting these signals, their source remains controversial. The dynamic nature of geologically active regions pose a number of key questions such as: (a), What role do pore fluids and heat fluxes have in generating the different styles of seismicity? (e.g. spatio-temporal evolution, signal frequency, amplitude and duration), and (b), How does the complex 3-D stress field influence the stability of these areas, in particular the volcano flank/edifice?

Such questions require responses that cut across the classical fields listed above, and to this end the rock mechanics laboratory takes a inter-disciplinary approach from fundamental geology methods to the latest applied geoscience techniques taken from the engineering community, as well as combining numerous modeling strategies. To facilitate this, as well as my primary affiliation above, I am appointed as adjunct professor at ETH Zurich (http://www.rockdeformation.ethz.ch/) and as honorary research fellow at University College London (http://www.es.ucl.ac.uk/ripl/), where a number of joint projects are based.  Specific areas of active research include:

• Dyke movement and arrest: how material properties affect the movement of magmas and dyke structures during magma transport.
• Mechanical properties of  crystal-bearing magma: Seismogenic lavas and eruption forecasting using laboratory AE location analysis and pore fabric characterisation.
• Forecasting material failure and geological hazard via passive seismicity and attenuation.
• Coupled Processes: linking Thermal-Hydraulic-Mechanical interactions in the shallow crust to passive seismic signals; Seismic precursors to earthquakes (‘Volcano-Tectonic’ and ‘Low Frequency’ harmonic events).
• Porous Media & Anisotropy: Investigation of fluid flow (permeability) anisotropy from elastic-wave anisotropy and 3D pore fabric anisotropy.

Recent Publications

More recent publications

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. In review.

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. In Press.

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.