Properties of the lithosphere: the view from the pressure vessel

Dan Faulkner Rock Deformation Laboratory University of Liverpool

Rock deformation

• Study of the physical and mechanical properties of Earth materials – Experiments – Microstructures – Fieldwork

Value of experimental work

• No phenomenon is a real phenomenon until it is an observed phenomenon. – John Archibald Wheeler

• No amount of experimentation can ever prove me right; a single experiment can prove me wrong. – Albert Einstein

Historical development

• 1680: Denis Papin develops the first autoclave • Von Karman (~1910) develops first ‘triaxial’ cell • P.W. Bridgman further develops high-pressure

technology – higher pressures possible • Francis Birch – application of high pressure to

Earth materials • David Griggs – solid-medium apparatus • Mervyn Paterson – gas-medium torsional

apparatus

Birch (1952)

High-pressure form Ordinary meaning

Certain Dubious

Undoubtedly Perhaps

Positive proof Vague suggestion

Unanswerable argument Trivial objection

Pure iron Uncertain mixture of all the elements

Unwary readers should take warning that ordinary language undergoes modification to a high-pressure form when applied to the interior of the Earth. A few examples of equivalents follow:

Lithospheric strength

Townend and Zoback, Geology, 2000

Kohlstedt et al. 1995 Goetze and Evans 1979 Brace et al. 1980

The strength of the ocean and continental lithosphere determined from laboratory experiments in the brittle and plastic regime

Earthquake rupture properties

Noda & Lapusta, 2013

Faulkner et al., 2011

Seismicity preceding eruptions

Burlini et al., 2007

Mantle anisotropy and rheology

San Andreas Fault Observatory at Depth

Lockner et al., 2011

Challenges

• Scaling (in time and space) • Fluid involvement in deformation

– Brittle crust – Plastic lithosphere

• Localization • Friction • Physical properties

UK Rock Deformation Network

• University of Edinburgh • University of Liverpool • University College London • University of Plymouth • University of Oxford • University of Manchester • University of Leicester • British Geological Survey • University of Durham

Opportunities • Drilling

– SAFOD – NanTroSeiZE – JFAST – DFDP

• Geodesy • Seismology • Industry

• Material developments • Innovative new design

– HV apparatus – High pressure apparatus

• New imaging techniques

Requirements • New equipment

development – DDia – Earthquake studies

• Confined HV rig • Rupture experiments

– Larger – to address scaling

– Microstructural techniques

• New materials – Drilling

• Closer collaboration with seismology/geodesy

D-Dia

Large friction apparatus

Properties of the lithosphere: the view from the pressure vesselRock deformationValue of experimental workHistorical developmentBirch (1952)Lithospheric strengthEarthquake rupture propertiesSeismicity preceding eruptionsMantle anisotropy and rheologySlide Number 10San Andreas Fault Observatory at DepthChallengesUK Rock Deformation NetworkOpportunitiesRequirements