Microphysics of evolving rock viscosity in the seismic and glacial cycles
Lead Research Organisation:
UNIVERSITY OF CAMBRIDGE
Department Name: Earth Sciences
Abstract
Despite being the epitome of strength, the solid rocks below Earth's surface can flow surprisingly rapidly over human timescales, impacting processes of societal relevance. This project aims to deliver new equations describing this flow based on the underlying processes operating in the rocks.
Major earthquakes and the melting of ice sheets cause deflections of Earth's surface that are facilitated by viscous flow of the hot rocks below. This deformation creates important feedbacks. During the seismic cycle, earthquakes induce viscous flow of rocks beneath the fault zone that impacts the spatial and temporal distributions of future earthquakes. During the glacial cycle, viscous flow of rocks beneath melting ice sheets causes ground uplift that impacts sea-level change. Therefore, modelling these systems requires knowledge of the viscosity of rocks in Earth's lower crust and upper mantle.
Unfortunately, the viscosities of these rocks are not constant but instead undergo a transient evolution whenever there is a change in the applied forces. Whilst we know that this viscosity evolution occurs, we do not know why. Without knowing the microscale processes that control the viscosity evolution, we cannot formulate equations that reliably predict flow of rocks in the Earth over the seismic and glacial cycles. At a time when populations exposed to seismic risk are rapidly expanding and when the modelling of ice-sheet dynamics is of unprecedented importance, it is critical to develop new models for the viscosity evolution of the rocks that underpin these systems.
Deciphering the microphysical processes that control the viscosity evolution of rocks requires an ambitious multidisciplinary approach. Each element of the research will be centred on the novel adaptation of techniques from the forefront of the materials sciences to analyse key geological minerals. Experiments will be conducted at temperatures up to 1500 degrees Celcius and will induce viscosity evolution by imposing instantaneous changes in the applied forces, analogous to those imposed by earthquakes. For the first time, a subset of the experiments will be performed inside a scanning electron microscope allowing the samples to be directly imaged during the tests. The microstructures of the samples will be analysed using state-of-the-art microscopy techniques, pioneered by our group, to measure distortions of the crystal lattices and the forces trapped within them. The combined mechanical data and microstructural observations will provide the new insights necessary to determine the key processes operating in the crystal lattices of the minerals that cause their viscosities to evolve.
The interpretations from the laboratory will be subject to two critical tests. To check the consistency and robustness of the interpretations, we will employ the latest models of deforming crystalline materials. We will adapt these models, developed to simulate metals, to analyse geological materials. The relevance of the laboratory experiments to natural rocks will be tested by comparing the microstructures of minerals from both settings. We will utilise samples from the deep portions of major fault zones that provide direct records of viscous flow in the lower crust and upper mantle.
The critical information gained from experiments, microstructural analyses, and modelling will be used to construct and calibrate new equations describing viscosity evolution. For the first time, the equations will be based on rigorous analyses of the specific underlying processes. These equations will unlock the next generation of large-scale models that incorporate the impacts of viscosity evolution in the seismic and glacial cycles. The mechanical and microstructural data generated in this project will be made freely available, providing a new and unique digital resource. Similarly, the techniques pioneered in this project will open new frontiers in the dynamics of geological materials.
Major earthquakes and the melting of ice sheets cause deflections of Earth's surface that are facilitated by viscous flow of the hot rocks below. This deformation creates important feedbacks. During the seismic cycle, earthquakes induce viscous flow of rocks beneath the fault zone that impacts the spatial and temporal distributions of future earthquakes. During the glacial cycle, viscous flow of rocks beneath melting ice sheets causes ground uplift that impacts sea-level change. Therefore, modelling these systems requires knowledge of the viscosity of rocks in Earth's lower crust and upper mantle.
Unfortunately, the viscosities of these rocks are not constant but instead undergo a transient evolution whenever there is a change in the applied forces. Whilst we know that this viscosity evolution occurs, we do not know why. Without knowing the microscale processes that control the viscosity evolution, we cannot formulate equations that reliably predict flow of rocks in the Earth over the seismic and glacial cycles. At a time when populations exposed to seismic risk are rapidly expanding and when the modelling of ice-sheet dynamics is of unprecedented importance, it is critical to develop new models for the viscosity evolution of the rocks that underpin these systems.
Deciphering the microphysical processes that control the viscosity evolution of rocks requires an ambitious multidisciplinary approach. Each element of the research will be centred on the novel adaptation of techniques from the forefront of the materials sciences to analyse key geological minerals. Experiments will be conducted at temperatures up to 1500 degrees Celcius and will induce viscosity evolution by imposing instantaneous changes in the applied forces, analogous to those imposed by earthquakes. For the first time, a subset of the experiments will be performed inside a scanning electron microscope allowing the samples to be directly imaged during the tests. The microstructures of the samples will be analysed using state-of-the-art microscopy techniques, pioneered by our group, to measure distortions of the crystal lattices and the forces trapped within them. The combined mechanical data and microstructural observations will provide the new insights necessary to determine the key processes operating in the crystal lattices of the minerals that cause their viscosities to evolve.
The interpretations from the laboratory will be subject to two critical tests. To check the consistency and robustness of the interpretations, we will employ the latest models of deforming crystalline materials. We will adapt these models, developed to simulate metals, to analyse geological materials. The relevance of the laboratory experiments to natural rocks will be tested by comparing the microstructures of minerals from both settings. We will utilise samples from the deep portions of major fault zones that provide direct records of viscous flow in the lower crust and upper mantle.
The critical information gained from experiments, microstructural analyses, and modelling will be used to construct and calibrate new equations describing viscosity evolution. For the first time, the equations will be based on rigorous analyses of the specific underlying processes. These equations will unlock the next generation of large-scale models that incorporate the impacts of viscosity evolution in the seismic and glacial cycles. The mechanical and microstructural data generated in this project will be made freely available, providing a new and unique digital resource. Similarly, the techniques pioneered in this project will open new frontiers in the dynamics of geological materials.
Organisations
- UNIVERSITY OF CAMBRIDGE (Lead Research Organisation)
- University College London (Collaboration)
- University of Oslo (Collaboration)
- University of Padova (Collaboration)
- University of Pennsylvania (Collaboration)
- Institute of Geology and Geophysics (Collaboration)
- Woods Hole Oceanographic Institution (Collaboration)
- UNIVERSITY OF LIVERPOOL (Collaboration)
- UNIVERSITY OF LEEDS (Collaboration)
- University of Manitoba (Collaboration)
- University of Otago (Collaboration)
- University of Portsmouth (Project Partner)
- University of Minnesota (Project Partner)
- Los Alamos National Laboratory (Project Partner)
Publications

Avadanii D
(2023)
The Role of Grain Boundaries in Low-Temperature Plasticity of Olivine Revealed by Nanoindentation
in Journal of Geophysical Research: Solid Earth

Fan S
(2023)
Grain growth of natural and synthetic ice at 0 °C
in The Cryosphere

Fan S
(2023)
Grain growth of natural and synthetic ice at 0 °C

Fan S
(2022)
Using Misorientation and Weighted Burgers Vector Statistics to Understand Intragranular Boundary Development and Grain Boundary Formation at High Temperatures
in Journal of Geophysical Research: Solid Earth

Gardner J
(2024)
Weighted Burgers Vector analysis of orientation fields from high-angular resolution electron backscatter diffraction.
in Ultramicroscopy


Harbord C
(2023)
Grain-Size Effects During Semi-Brittle Flow of Calcite Rocks
in Journal of Geophysical Research: Solid Earth

Kumamoto K
(2024)
The Effect of Intracrystalline Water on the Mechanical Properties of Olivine at Room Temperature
in Geophysical Research Letters

Plümper O
(2022)
High-magnitude stresses induced by mineral-hydration reactions
in Geology

Rutter E
(2022)
Application of Electron Backscatter Diffraction to Calcite-Twinning Paleopiezometry
in Geosciences
Description | Although this research is at an early stage, we have made significant progress in understanding how the strength of hot rocks that flow in a ductile manner deep within Earth is controlled by microscale processes operating within the constituent crystals. The flow of these deep rocks impacts shallower processes, including the behaviour of fault zones that generate major earthquakes and also how the ground rebounds as ice sheets melt. Being able to model the flow of these deep rocks is therefore important in analysing the behaviour of faults over the earthquake cycle and how the rebound of the solid earth affects the rates of ice loss during global warming. However, these modelling efforts have been hindered by our lack of understanding of the microscale processes by which hot rocks can flow, particularly in contexts where the force applied to the rock changes rapidly, such as in the aftermath of an earthquake or during the melting of an ice sheet. Our experiments have provided new insights into how exactly the flow of hot rocks depends on the behaviour of defects in the crystal lattices of their constituent minerals. Our work on the mineral olivine has revealed that elastic forces acting among the defects control the rate at which rocks in Earth's mantle can flow and has revealed that the multiplication of these defects causes the strength of the rock to evolve dramatically during flow. A parallel set of experiments on rock salt have revealed even more complex interactions among the lattice defects demonstrating how the flow behaviour differs between minerals with different crystal structures. These results on rock salt are relevant to applications involving storage of waste or energy in underground salt caverns. For both minerals, we are formulating equations based and calibrated on our results that can be used to predict the behaviour of rocks deep in Earth's interior. |
Exploitation Route | Our work on the mineral olivine is providing equations that can be applied to predict the behaviour of fault zones over the earthquake cycle and rebound of the solid earth in response to melting ice sheets. These are areas of intense academic research interest and we are already working with collaborators directly to incorporate our equations into models of these large-scale processes. The improved fault-zone and ice-sheet models that we will generate could have impacts the earthquake-hazard and environmental sectors respectively. Our work on the mineral halite is providing equations that can be applied to predict the behaviour of underground salt caverns that are a key target for storage of fuel or waste from the energy sector. |
Sectors | Energy Environment |
Description | Conditions for earthquake nucleation in the lower crust |
Amount | kr 14,415,000 (NOK) |
Funding ID | 334965 |
Organisation | Research Council of Norway |
Sector | Public |
Country | Norway |
Start | 06/2023 |
End | 06/2027 |
Description | Transient deformation in the upper mantle due to present-day deglaciation and earthquakes |
Amount | € 295,137 (EUR) |
Funding ID | ENW.GO.001.005 |
Organisation | Netherlands Space Office |
Sector | Public |
Country | Netherlands |
Start | 01/2023 |
End | 12/2026 |
Title | Berkovich nanoindentation and FTIR data describing the effect of water on olivine plasticity |
Description | This data set contains data collected as part of a study to determine the influence of dissolved hydrogen on the mechanical properties of olivine. Nanoindentation experiments were conducted to measure the hardness of both pristine olivine crystals and olivine crystals predoped with hydrogen. The hydrogen content of samples was assessed with Fourier-transform infrared spectroscopy (FTIR). This data set includes mechanical data from indentation experiments as well as spectra from FTIR measurements. This deposit contains data associated with: K.M. Kumamoto, L.N. Hansen, T.P. Breithaupt, D. Wallis, B.-S. Li, D.E.J. Armstrong, D.L. Goldsby, Y. Li, J.M. Warren, and A.J. Wilkinson The effect of intracrystalline water on the mechanical properties of olivine at room temperature Submitted to Geophysical Research Letters. |
Type Of Material | Database/Collection of data |
Year Produced | 2023 |
Provided To Others? | Yes |
Impact | N/A |
URL | https://conservancy.umn.edu/handle/11299/256166 |
Title | Decorated dislocations and (HR-)EBSD data from olivine of the Oman-UAE ophiolite |
Description | This dataset is supplemental to the paper Wallis et al. (2021) and contains data on dislocations and their stress fields in olivine from the Oman-UAE ophiolite measured by oxidation decoration, electron backscatter diffraction (EBSD) and high-angular resolution electron backscatter diffraction (HR-EBSD). The datasets include images of decorated dislocations, measurements of lattice orientation and misorientations, densities of geometrically necessary dislocations, and heterogeneity in residual stress. Data are provided as 6 TIF files, 8 CTF files, and 37 tab-delimited TXT files. Files are organised by the figure in which the data are presented in the main paper. Data types or sample numbers are also indicated in the file names. |
Type Of Material | Database/Collection of data |
Year Produced | 2021 |
Provided To Others? | Yes |
Impact | This is the first dataset on stress heterogeneity within individual grains of the mineral olivine deformed in Earth's mantle. As the analysis of such stress fields is a key research direction for my group and others, this dataset provides an important benchmark against which to assess the quality and significance of future measurements. |
URL | https://dataservices.gfz-potsdam.de/panmetaworks/showshort.php?id=75f19561-5dc9-11ec-958d-ed2b0fcbcc... |
Title | Grain size effects during the semi-brittle flow of calcite rocks |
Description | Dataset containing measurements of strain, stress and relative changes in acoustic velocity (where available) relating to the manuscript "Grain size effects during the semi-brittle flow of calcite rocks". |
Type Of Material | Database/Collection of data |
Year Produced | 2022 |
Provided To Others? | Yes |
Impact | N/A |
URL | https://zenodo.org/record/7347236 |
Description | Grain growth of natural and synthetic ice at 0 °C |
Organisation | Institute of Geology and Geophysics |
Country | China |
Sector | Public |
PI Contribution | I assisted in interpretation of data from electron backscatter diffraction on grain growth in ice. |
Collaborator Contribution | My collaborators fabricated ice samples, performed grain growth experiments, collected data by electron backscatter diffraction, and analysed and interpreted the results. |
Impact | doi:10.5194/tc-17-3443-2023 |
Start Year | 2022 |
Description | Grain growth of natural and synthetic ice at 0 °C |
Organisation | University of Leeds |
Department | School of Earth and Environment |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | I assisted in interpretation of data from electron backscatter diffraction on grain growth in ice. |
Collaborator Contribution | My collaborators fabricated ice samples, performed grain growth experiments, collected data by electron backscatter diffraction, and analysed and interpreted the results. |
Impact | doi:10.5194/tc-17-3443-2023 |
Start Year | 2022 |
Description | Grain growth of natural and synthetic ice at 0 °C |
Organisation | University of Otago |
Country | New Zealand |
Sector | Academic/University |
PI Contribution | I assisted in interpretation of data from electron backscatter diffraction on grain growth in ice. |
Collaborator Contribution | My collaborators fabricated ice samples, performed grain growth experiments, collected data by electron backscatter diffraction, and analysed and interpreted the results. |
Impact | doi:10.5194/tc-17-3443-2023 |
Start Year | 2022 |
Description | Grain growth of natural and synthetic ice at 0 °C |
Organisation | University of Pennsylvania |
Country | United States |
Sector | Academic/University |
PI Contribution | I assisted in interpretation of data from electron backscatter diffraction on grain growth in ice. |
Collaborator Contribution | My collaborators fabricated ice samples, performed grain growth experiments, collected data by electron backscatter diffraction, and analysed and interpreted the results. |
Impact | doi:10.5194/tc-17-3443-2023 |
Start Year | 2022 |
Description | Grain-Size Effects During Semi-Brittle Flow of Calcite Rocks |
Organisation | University College London |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | I collected and assisted in the interpretation of data from electron backscatter diffraction and high-angular resolution electron backscatter diffraction. |
Collaborator Contribution | My collaborators fabricated samples of limestone and marble, analysed data from electron backscatter diffraction and high-angular resolution electron backscatter diffraction, and assisted in the data interpretation. |
Impact | doi:10.1029/2023JB026458 |
Start Year | 2021 |
Description | On-fault earthquake energy density partitioning from shocked garnet in an exhumed seismogenic mid-crustal fault |
Organisation | University of Manitoba |
Country | Canada |
Sector | Academic/University |
PI Contribution | I provided guidance on the acquisition, processing, analysis, and interpretation of data obtained by high-angular resolution electron backscatter diffraction to assess energy stored in fault rock during an earthquake. |
Collaborator Contribution | My partners collected the samples and data from a rock recording an earthquake in the lower crust of Australia. |
Impact | doi:10.1126/sciadv.adi8533 |
Start Year | 2022 |
Description | On-fault earthquake energy density partitioning from shocked garnet in an exhumed seismogenic mid-crustal fault |
Organisation | University of Oslo |
Country | Norway |
Sector | Academic/University |
PI Contribution | I provided guidance on the acquisition, processing, analysis, and interpretation of data obtained by high-angular resolution electron backscatter diffraction to assess energy stored in fault rock during an earthquake. |
Collaborator Contribution | My partners collected the samples and data from a rock recording an earthquake in the lower crust of Australia. |
Impact | doi:10.1126/sciadv.adi8533 |
Start Year | 2022 |
Description | On-fault earthquake energy density partitioning from shocked garnet in an exhumed seismogenic mid-crustal fault |
Organisation | University of Padova |
Department | Department of Geosciences |
Country | Italy |
Sector | Academic/University |
PI Contribution | I provided guidance on the acquisition, processing, analysis, and interpretation of data obtained by high-angular resolution electron backscatter diffraction to assess energy stored in fault rock during an earthquake. |
Collaborator Contribution | My partners collected the samples and data from a rock recording an earthquake in the lower crust of Australia. |
Impact | doi:10.1126/sciadv.adi8533 |
Start Year | 2022 |
Description | Using misorientation and weighted Burgers vector statistics to understand intragranular boundary development and grain boundary formation at high temperatures |
Organisation | University of Liverpool |
Department | Department of Earth, Ocean and Ecological Sciences |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | I assisted in the interpretation of data from electron backscatter diffraction. |
Collaborator Contribution | My collaborators fabricated sample of ice, performed deformation experiments, collected data by electron backscatter diffraction, and analysed and interpreted the results. |
Impact | doi:10.1029/2022JB024497 |
Start Year | 2022 |
Description | Using misorientation and weighted Burgers vector statistics to understand intragranular boundary development and grain boundary formation at high temperatures |
Organisation | University of Otago |
Country | New Zealand |
Sector | Academic/University |
PI Contribution | I assisted in the interpretation of data from electron backscatter diffraction. |
Collaborator Contribution | My collaborators fabricated sample of ice, performed deformation experiments, collected data by electron backscatter diffraction, and analysed and interpreted the results. |
Impact | doi:10.1029/2022JB024497 |
Start Year | 2022 |
Description | Using misorientation and weighted Burgers vector statistics to understand intragranular boundary development and grain boundary formation at high temperatures |
Organisation | University of Pennsylvania |
Country | United States |
Sector | Academic/University |
PI Contribution | I assisted in the interpretation of data from electron backscatter diffraction. |
Collaborator Contribution | My collaborators fabricated sample of ice, performed deformation experiments, collected data by electron backscatter diffraction, and analysed and interpreted the results. |
Impact | doi:10.1029/2022JB024497 |
Start Year | 2022 |
Description | Using misorientation and weighted Burgers vector statistics to understand intragranular boundary development and grain boundary formation at high temperatures |
Organisation | Woods Hole Oceanographic Institution |
Country | United States |
Sector | Charity/Non Profit |
PI Contribution | I assisted in the interpretation of data from electron backscatter diffraction. |
Collaborator Contribution | My collaborators fabricated sample of ice, performed deformation experiments, collected data by electron backscatter diffraction, and analysed and interpreted the results. |
Impact | doi:10.1029/2022JB024497 |
Start Year | 2022 |