Fluid chemistry and earthquake rupture

Overview

Earthquakes are among the most disastrous natural events, claiming, in the last three decades alone, several hundreds of thousands victims and $500 billion in economic losses. Earthquakes result from the sudden release of tectonic stress which builds up in the relatively brittle rocks of the upper crust. In the deeper crust (generally >15km) rocks are more plastic and less prone to sudden, seismic brittle failure. However, even in the upper crust faults can move aseismically (creep), depending on the combination of temperature, pressure and fluids which affect the frictional behaviour of fault materials, and on how recently the fault has been sliding.
By experimenting on synthetic and natural fault materials, Earth scientists have learned much about the restrengthening of fault zones after earthquake rupture, the strength profiles of different fault materials, their ability to promote or arrest failure, and the importance of the permeability of fault rocks. Aqueous fluids are paramount in modulating the earthquake cycle and rupture; their role has been deliberated in the past decades, devoting particular attention to the restrengthening and alteration of material properties (Evans et al., 1995; Boulton et al., 2012; Wästeby et al., 2014; Boulton et al., 2017), the pressure cycling during earthquake nucleation (Blanpied et al., 1992), the thermal pressurisation due to frictional heating (Wibberley and Shimamoto, 2005), and the redistribution of heat in the crust surrounding fault zones (Wang et al., 2013; Sutherland et al., 2017; Coussens et al., 2018). In spite of these pioneering studies, many aspects are poorly understood. For example, it is not clear how the chemical reactions that take place through the earthquake cycle can affect the fault behaviour, what is the fluid’s role in sealing the fault zone, and how subtle changes in the regional chemistry may reveal fault activity.
This project will investigate and characterise co-seismic chemical reactions that modulate pore fluid chemistry and mineralogy of fault zones. Rocks will be experimentally faulted in contact with a hydrothermal fluid to interrogate co-seismic chemical reactions. Fluid and rock samples will be geochemically characterised prior to, and after experimental work to identify mineralogical and chemical changes that occur during simulated earthquake slip under different conditions. These changes will then be related to variability measured in the fluid permeability, mechanical and frictional properties of the investigated materials to identify the chemical reactions that occur and their control on earthquake rupture and propagation processes. Such work coupling geochemical analyses of simulated fluids and rocks during simulated earthquake slip has only been documented in few instances to date (Violay et al. 2012).

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Image Captions

Fig1.png Fig. 1. Cross section of a continental scale fault zone showing factors likely to control the earthquake cycle. Inset shows the permeability profile of the Alpine Fault, New Zealand. Modified after Sutherland et al., 2012.
Fig2.png Fig. 2. Schematic summary cross section of restrengthening of the Alpine Fault zone (New Zealand) due to fluid-rock interactions and sealing of fractures throughout the seismic cycle. After Boulton et al., 2017.
Fig3.png Fig. 3. Microprobe image of a calcite grain surrounded by a halo of newly formed mineral (brightest white, wollastonite) produced during a hydrothermal friction experiment at Utrecht University (Niemeijer et al., 2016).

Methodology

Aims of this project:
a. To assess changes in chemistry and isotopic composition of pore fluid during simulated earthquake rupture on a variety of materials and fluid compositions
b. To assess the changes in mineralogy during simulated earthquake rupture on a variety of materials and fluid compositions
c. To compare results to real data from a continental scale fault zone, ie the Alpine Fault, New Zealand
These aims will be achieved through experiments carried out in the Durham Rock Mechanics Laboratory and analyses of the fluids and rock products in the Arthur Holmes Geochemistry Laboratories at Durham, and the NERC Isotope Laboratories at SUERC, as well as SEM imaging at the Durham Microscopy and Bioimaging Facility. Complementary experiments will be conducted at Utrecht University under the supervision of Dr Andre Niemeijer. Samples will be collected from the Alpine Fault in New Zealand to supplement natural sample testing.

Project Timeline

Year 1

Thorough literature review; training in experimental set up and elemental and isotopic measurements. Initial experiments and analyses and planning of future experimental work. Plan and carry out fieldwork in New Zealand to collect samples for Y2.

Year 2

Continuation of experimental design; visit SUERC to start stable isotope analyses; visit Dr Niemeijer in Utrecht to carry out some experiments under differing conditions.

Year 3

Completion of experiments; completion of isotopic and chemical analyses; attend and international conference to present work.

Year 3.5

Finalising models; writing up thesis and preparation of manuscripts for publication.

Training
& Skills

1. Training in the design of experiments and use instrumentation in the Durham Rock Mechanics Laboratory and apparatus in the rock mechanics lab at Utrecht University.
2. Training in the preparation of geological materials for geochemical analyses and measurement of elemental and isotopic compositions of both rock and fluid samples.
3. Training in analyses of H and O stable isotopes in silicates at SUERC.
4. Presentation of research at national and international conferences
5. Training in writing skills through detailed feedback on manuscripts and thesis drafts

References & further reading

Blanpied, M. L., Lockner, D. A., and Byerlee, J. D., 1992, An earthquake mechanism based on rapid sealing of faults: Nature, v. 358, no. 3, p. 574-576.
Boulton, C., Carpenter, B. M., Toy, V., and Marone, C., 2012, Physical properties of surface outcrop cataclastic fault rocks, Alpine Fault, New Zealand: Geochem. Geophys. Geosyst., v. 13, p. Q01018.
Boulton, C., Menzies, C. D., Toy, V. G., Townend, J., and Sutherland, R., 2017, Geochemical and microstructural evidence for interseismic changes in fault zone permeability and strength, Alpine Fault, New Zealand: Geochemistry, Geophysics, Geosystems, v. 18, no. 1, p. 238-265.
Coussens, J., Woodman, N., Upton, P., Menzies, C. D., Janku-Capova, L., Sutherland, R., and Teagle, D. A. H., 2018, The significance of heat transport by shallow fluid flow at an active plate boundary: the Southern Alps, New Zealand: Geophysical Research Letters, v. 45, no. 19, p. 10323-10331.
Evans, J. P., and Chester, F. M., 1995, Fluid-rock interaction in faults of the San Andreas system: Inferences from San Gabriel fault rock geochemistry and microstructures: Journal of Geophysical Research: Solid Earth, v. 100, no. B7, p. 13007-13020.
Niemeijer, A. R., Boulton, C., Toy, V. G., Townend, J., and Sutherland, R., 2016, Large-displacement, hydrothermal frictional properties of DFDP-1 fault rocks, Alpine Fault, New Zealand: Implications for deep rupture propagation: Journal of Geophysical Research: Solid Earth, v. 121, no. 2, p. 624-647.
Segall, P., and Rice, J. R., 2006, Does shear heating of pore fluid contribute to earthquake nucleation?: Journal of Geophysical Research: Solid Earth, v. 111, no. B9, p. B09316.
Sutherland, R., Townend, J., Toy, V., Upton, P., Coussens, J., Allen, M., Baratin, L.-M., Barth, N., Becroft, L., Boese, C., Boles, A., Boulton, C., Broderick, N. G. R., Janku-Capova, L., Carpenter, B. M., Célérier, B., Chamberlain, C., Cooper, A., Coutts, A., Cox, S., Craw, L., Doan, M.-L., Eccles, J., Faulkner, D., Grieve, J., Grochowski, J., Gulley, A., Hartog, A., Howarth, J., Jacobs, K., Jeppson, T., Kato, N., Keys, S., Kirilova, M., Kometani, Y., Langridge, R., Lin, W., Little, T., Lukacs, A., Mallyon, D., Mariani, E., Massiot, C., Mathewson, L., Melosh, B., Menzies, C. D., Moore, J., Morales, L., Morgan, C., Mori, H., Niemeijer, A., Nishikawa, O., Prior, D., Sauer, K., Savage, M., Schleicher, A., Schmitt, D. R., Shigematsu, N., Taylor-Offord, S., Teagle, D., Tobin, H., Valdez, R., Weaver, K., Wiersberg, T., Williams, J., Woodman, N., and Zimmer, M., 2017, Extreme hydrothermal conditions at an active plate-bounding fault: Nature, v. 546, p. 137-140.
Violay, M., Nielsen, S., Spagnuolo,E., Cinti, D., Di Toro, G., Di Stefano, G., 2012. Pore fluid in experimental calcite-bearing faults: Abrupt weakening and geochemical signature of co-seismic processes. Earth and Planetary Science Letters, 361. DOI: 10.1016/j.epsl.2012.11.021
Wang, C.-Y., Wang, L.-P., Manga, M., Wang, C.-H., and Chen, C.-H., 2013, Basin-scale transport of heat and fluid induced by earthquakes: Geophysical Research Letters, v. 40, no. 15, p. 3893-3897.
Wästeby, N., Skelton, A., Tollefsen, E., Andrén, M., Stockmann, G., Liljedahl, L. C., Sturkell, E., and Mörth, M., 2014, Hydrochemical monitoring, petrological observation and geochemical modelling of fault healing after an earthquake: Journal of Geophysical Research: Solid Earth, p. 2013JB010715.
Wibberley, C. A. J., and Shimamoto, T., 2005, Earthquake slip weakening and asperities explained by thermal pressurization: Nature, v. 436, no. 7051, p. 689-692.

Further Information

Contact Dr Catriona Menzies (catriona.d.menzies@durham.ac.uk; tel:+44 (0)191 334 4603) or Prof Stefan Nielsen (stefan.nielsen@durham.ac.uk; +44 (0) 191 3344308) for further details.

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