How do earthquake ruptures propagate through clay-rich fault zones?
Lead Research Organisation:
University of Liverpool
Department Name: Earth, Ocean and Ecological Sciences
Abstract
On large tectonic faults movement can occur stably, producing fault creep, or by unstable slip where earthquakes occur. Fault creep has typically been associated with clay-rich fault gouges that accommodate slip across a fault. They have typically been thought to pose less seismic hazard than locked faults where earthquakes occur periodically. Recent studies have demonstrated that earthquakes can propagate through creeping sections of faults, with devastating consequences. This project will combine leading experimentalists and modellers to investigate under what conditions earthquake ruptures can propagate through 'creeping' faults. The work will utilize a unique new high-pressure rotary shear deformation apparatus to replicate and understand the physical response as an earthquake rupture passes and rupture models predict the large-scale response. Results from experiments and modelling will be used to develop new seismic hazard assessment for creeping faults, both in terms of how their potential for seismicity is viewed, and how the nature of a rupture would affect the radiated wavefield - which influences how destructive an earthquake will be.
We know from slow-slip laboratory experiments that earthquakes are not expected to nucleate on clay-rich faults as they strengthen as slip starts to accelerate, thereby arresting any potential rupture. This is nicely illustrated by a lack of seismicity seen in the accretionary forearc clay-rich parts of subduction zones. However, recent events have suggested that large earthquake rupture, nucleated on a less clay-rich region of a fault zone can punch through clay-rich regions, and even greatly enhance slip, such as was seen in the Mw9.0 Tohoku-Oki earthquake in 2011, where the largest co-seismic slip ever recorded (~50m) occurred in the clay-rich accretionary forearc that produced a large offset of the seafloor leading to a devastating tsunami. Other examples of where earthquakes have propagated through creeping faults are The 1999 Mw7.6 Chi Chi earthquake in Taiwan, there the properties of the rupture were clearly modified (increase in the rupture velocity and slip speed), and the 1944 Mw7.4 North Anatolian Fault earthquake.
This research will use unique laboratory equipment recently developed at Liverpool that can replicate the conditions during earthquakes and allow us to measure how the frictional strength of the fault develops, which will dictate whether or not an earthquake rupture will propagate or arrest in clay-rich faults. It will allow the approach of an earthquake ruptures to be simulated under fully confined conditions approximating to 15km depth. Experiments will be conducted where the strength and properties of the experimental fault zone is monitored under different imposed displacements and displacement rates. The peak acceleration and stress reduction will mimic earthquakes of different size and investigate the energy barrier required to promote unstable slip. In a different type of experiment, a stick-slip instability (laboratory earthquake) will be monitored as it propagates into clay-rich region of a laboratory fault zone.
Results constraining the physical response of earthquake slip from the laboratory will be added into large-scale models to aid our understanding of (a) rupture propagation, which will dictate if a small earthquake will grow into large event and (b) what the properties will be, such as how fast it will travel and how much stress will be released, for use in probabilistic seismic hazard assessment.
We know from slow-slip laboratory experiments that earthquakes are not expected to nucleate on clay-rich faults as they strengthen as slip starts to accelerate, thereby arresting any potential rupture. This is nicely illustrated by a lack of seismicity seen in the accretionary forearc clay-rich parts of subduction zones. However, recent events have suggested that large earthquake rupture, nucleated on a less clay-rich region of a fault zone can punch through clay-rich regions, and even greatly enhance slip, such as was seen in the Mw9.0 Tohoku-Oki earthquake in 2011, where the largest co-seismic slip ever recorded (~50m) occurred in the clay-rich accretionary forearc that produced a large offset of the seafloor leading to a devastating tsunami. Other examples of where earthquakes have propagated through creeping faults are The 1999 Mw7.6 Chi Chi earthquake in Taiwan, there the properties of the rupture were clearly modified (increase in the rupture velocity and slip speed), and the 1944 Mw7.4 North Anatolian Fault earthquake.
This research will use unique laboratory equipment recently developed at Liverpool that can replicate the conditions during earthquakes and allow us to measure how the frictional strength of the fault develops, which will dictate whether or not an earthquake rupture will propagate or arrest in clay-rich faults. It will allow the approach of an earthquake ruptures to be simulated under fully confined conditions approximating to 15km depth. Experiments will be conducted where the strength and properties of the experimental fault zone is monitored under different imposed displacements and displacement rates. The peak acceleration and stress reduction will mimic earthquakes of different size and investigate the energy barrier required to promote unstable slip. In a different type of experiment, a stick-slip instability (laboratory earthquake) will be monitored as it propagates into clay-rich region of a laboratory fault zone.
Results constraining the physical response of earthquake slip from the laboratory will be added into large-scale models to aid our understanding of (a) rupture propagation, which will dictate if a small earthquake will grow into large event and (b) what the properties will be, such as how fast it will travel and how much stress will be released, for use in probabilistic seismic hazard assessment.
Planned Impact
This work aims to constrain fundamental aspects of the earthquake source and determine how this might affect seismic hazard assessment. These aims have the potential to inform and benefit a wide range of end users. Potential beneficiaries can be divided into several categories:
1. Policy makers that make use of probabalisitic seismic hazard assessment to inform planning regulations. There are two aspects to this; first hazard maps are based on the knowledge of the location of seismic faults. Creeping faults have typically been viewed as less hazardous, but information on when they could potentially allow seismic rupture will allow a re-assessment of risk maps in seismically active areas. The second aspect relates to the near-field shaking associated with rupture through clay-rich faults. This work will investigate the effect of source characteristics on the radiated wave-field that will help to establish the magnitude of peak ground acceleration and ground shaking associated with a rupture along a clay-rich patch of a fault.
2. Industry. Induced seismicity associated with injection into the sub-surface is a key issue for shale gas exploitation, geothermal energy and carbon dioxide storage. Shale gas is a potentially important future component of the UK's energy needs. However there are significant issues regarding induced seismicity in the UK where the population density is high. Induced seismic events during fracking occur within clay-rich horizons and understanding processes leading to propagation and arrest of ruptures will help to reduce risk. The same issues are faced by geothermal exploitation, where enhanced geothermal projects actively fracture the rock mass, potentially leading to induced events, such as occurred during the Basel and St Gallen geothermal projects in Switzerland. Low-enthalpy geothermal energy is becoming a key potential future energy source for Europe, for example, the Swiss committing to 30% of their power from geothermal sources by 2050. Finally, carbon storage projects are essential to the short-term reduction of carbon output. Key to this process is ensuring the integrity of top seals and fault seals to storage sites during injection and storage. Co-seismic damage to seals from induced events is an area what requires investigation. In summary, enhancing our understanding of rupture propagation through clay-rich sequences will allow better planning of safe injection rates for shale gas, geothermal and carbon dioxide storage, likely magnitude of induced events, and long-term management of storage facilities.
3. General public. Large-scale earth processes such as earthquakes captures the public imagination. It feeds interest in science and encourages younger people into careers that are essential for the future economic and environmental development of the UK and beyond. Additionally, education of the general public about the science behind processes such as fracking are essential in order to gain public acceptance for energy initiatives vital to the future economic well-being of the UK.
1. Policy makers that make use of probabalisitic seismic hazard assessment to inform planning regulations. There are two aspects to this; first hazard maps are based on the knowledge of the location of seismic faults. Creeping faults have typically been viewed as less hazardous, but information on when they could potentially allow seismic rupture will allow a re-assessment of risk maps in seismically active areas. The second aspect relates to the near-field shaking associated with rupture through clay-rich faults. This work will investigate the effect of source characteristics on the radiated wave-field that will help to establish the magnitude of peak ground acceleration and ground shaking associated with a rupture along a clay-rich patch of a fault.
2. Industry. Induced seismicity associated with injection into the sub-surface is a key issue for shale gas exploitation, geothermal energy and carbon dioxide storage. Shale gas is a potentially important future component of the UK's energy needs. However there are significant issues regarding induced seismicity in the UK where the population density is high. Induced seismic events during fracking occur within clay-rich horizons and understanding processes leading to propagation and arrest of ruptures will help to reduce risk. The same issues are faced by geothermal exploitation, where enhanced geothermal projects actively fracture the rock mass, potentially leading to induced events, such as occurred during the Basel and St Gallen geothermal projects in Switzerland. Low-enthalpy geothermal energy is becoming a key potential future energy source for Europe, for example, the Swiss committing to 30% of their power from geothermal sources by 2050. Finally, carbon storage projects are essential to the short-term reduction of carbon output. Key to this process is ensuring the integrity of top seals and fault seals to storage sites during injection and storage. Co-seismic damage to seals from induced events is an area what requires investigation. In summary, enhancing our understanding of rupture propagation through clay-rich sequences will allow better planning of safe injection rates for shale gas, geothermal and carbon dioxide storage, likely magnitude of induced events, and long-term management of storage facilities.
3. General public. Large-scale earth processes such as earthquakes captures the public imagination. It feeds interest in science and encourages younger people into careers that are essential for the future economic and environmental development of the UK and beyond. Additionally, education of the general public about the science behind processes such as fracking are essential in order to gain public acceptance for energy initiatives vital to the future economic well-being of the UK.
Organisations
- University of Liverpool (Lead Research Organisation)
- California Institute of Technology (Collaboration)
- Japan Agency for Marine-Earth Science and Technology (Collaboration)
- Ben-Gurion University of the Negev (Collaboration)
- California Institute of Technology (Project Partner)
- Brown University (Project Partner)
- Institut de Physique du Globe de Paris (Project Partner)
Publications
Bedford J
(2021)
The stabilizing effect of high pore-fluid pressure along subduction megathrust faults: Evidence from friction experiments on accretionary sediments from the Nankai Trough
in Earth and Planetary Science Letters
Bedford J
(2021)
The Role of Grain Size and Effective Normal Stress on Localization and the Frictional Stability of Simulated Quartz Gouge
in Geophysical Research Letters
Bedford JD
(2022)
Fault rock heterogeneity can produce fault weakness and reduce fault stability.
in Nature communications
Beynon S
(2020)
Dry, damp, or drenched? The effect of water saturation on the frictional properties of clay fault gouges
in Journal of Structural Geology
Boulton C
(2017)
High-velocity frictional properties of Alpine Fault rocks: Mechanical data, microstructural analysis, and implications for rupture propagation
in Journal of Structural Geology
Den Hartog S
(2021)
How do Laboratory Friction Parameters Compare With Observed Fault Slip and Geodetically Derived Friction Parameters? Insights From the Longitudinal Valley Fault, Taiwan
in Journal of Geophysical Research: Solid Earth
Den Hartog S
(2020)
Low Friction Coefficient of Phyllosilicate Fault Gouges and the Effect of Humidity: Insights From a New Microphysical Model
in Journal of Geophysical Research: Solid Earth
Faulkner D
(2018)
Pore Fluid Pressure Development in Compacting Fault Gouge in Theory, Experiments, and Nature
in Journal of Geophysical Research: Solid Earth
Lambert V
(2021)
Scale Dependence of Earthquake Rupture Prestress in Models With Enhanced Weakening: Implications for Event Statistics and Inferences of Fault Stress
in Journal of Geophysical Research: Solid Earth
Passelègue F
(2018)
Development and Recovery of Stress-Induced Elastic Anisotropy During Cyclic Loading Experiment on Westerly Granite
in Geophysical Research Letters
Seyler C
(2020)
Rupture to the trench? Frictional properties and fracture energy of incoming sediments at the Cascadia subduction zone
in Earth and Planetary Science Letters
Sánchez-Roa C
(2018)
Implications of sepiolite dehydration for earthquake nucleation in the Galera Fault Zone: A thermodynamic approach
in Applied Geochemistry
Sánchez-Roa C
(2017)
How phyllosilicate mineral structure affects fault strength in Mg-rich fault systems
in Geophysical Research Letters
Tal Y
(2022)
The Effect of Fault Roughness and Earthquake Ruptures on the Evolution and Scaling of Fault Damage Zones
in Journal of Geophysical Research: Solid Earth
Description | We have found that compaction during shear in fault zones can pressurize fluids in the pore space and potentially lead to earthquake nucleation. The weakening of fault gouges in this way has been quantified by numerical modelling and experiments. We have quantified the effect of fault zone heterogeneity on the strength and seismic potential of faults. Having patches of weak, rate strengthening, fault gouge has a disproportionally large effect and weakens faults more than might be expected and also promotes instability more than is expected. We have found that fault roughness is the key parameter in controlling the development and growth of fault damage zones. |
Exploitation Route | These findings will not be incorporated into earthquake rupture models to help identify conditions under which earthquakes can occur. |
Sectors | Education Energy Environment Financial Services and Management Consultancy |
Description | The findings of how earthquakes nucleate, propagate, and arrest has been communicated through two media interviews, one to local BBC radio news in 2023 and one to the international BBC News Channel in January 2024. These were media interviews that were commenting on local earthquakes in Essex (BBC Radio) and the 2024 Mw7.5 Noto earthquake in Japan. |
First Year Of Impact | 2023 |
Sector | Education,Energy,Environment,Financial Services, and Management Consultancy |
Impact Types | Societal Economic Policy & public services |
Description | Co-author on NSF white paper |
Geographic Reach | North America |
Policy Influence Type | Membership of a guideline committee |
Impact | This white paper will influence US Federal funding of earthquake science funding over the next 10 years. |
Description | Panel member to write proposal for NERC call |
Geographic Reach | National |
Policy Influence Type | Participation in a guidance/advisory committee |
Impact | A £5M NERC and Nuclear Waste Services call arose from the scoping document our committee wrote. The funded project will provide essential scientific data that contribute towards UK's future energy security and also help communication to the public about the eventual siting of a Geological Disposal Facility that is based on sound scientific research. |
URL | https://www.ukri.org/opportunity/derisking-geological-disposal-of-radioactive-waste-in-the-uk/ |
Description | FY2022 JSPS Invitational Fellowships for Research in Japan (Short-term) |
Amount | ¥850,000 (JPY) |
Funding ID | S22037 |
Organisation | Japan Society for the Promotion of Science (JSPS) |
Sector | Public |
Country | Japan |
Start | 07/2022 |
End | 09/2022 |
Description | NSFGEO-NERC Earthquake nucleation versus episodic slow slip: what controls the mode of fault slip? |
Amount | £408,234 (GBP) |
Funding ID | NE/V011804/1 |
Organisation | Natural Environment Research Council |
Sector | Public |
Country | United Kingdom |
Start | 12/2021 |
End | 03/2024 |
Title | Confined high pressure high velocity rotary shear apparatus |
Description | This apparatus can perform friction measurements under conditions comparable to those found during earthquake slip in the earth's crust. |
Type Of Material | Improvements to research infrastructure |
Year Produced | 2017 |
Provided To Others? | No |
Impact | It is producing data for the project. |
Description | Caltech earthquake modelling |
Organisation | California Institute of Technology |
Country | United States |
Sector | Academic/University |
PI Contribution | We are combining experimental constraints to earthquake rupture models to understand the behaviour of large earthquakes. My part of the collaboration is to provide experimental and field expertise. |
Collaborator Contribution | Modelling expertise. |
Impact | Currently working on several papers. The result of previous collaborations was this NERC-NSF award. |
Start Year | 2016 |
Description | Fault roughness modeling |
Organisation | Ben-Gurion University of the Negev |
Country | Israel |
Sector | Academic/University |
PI Contribution | Developed a collaborative project with Dr. Yuval Tal to understand how fault roughness affects fault damage zone properties. I shared mechanical and field data as input to the model and co-wrote a submitted manuscript on the results. |
Collaborator Contribution | Dr. Tal developed the idea/concept of the project, performed the numerical modeling and co-wrote the manuscript. |
Impact | 2 conference abstracts 1 submitted manuscript, now in revision. |
Start Year | 2018 |
Description | JSPS Fellowhip |
Organisation | Japan Agency for Marine-Earth Science and Technology |
Country | Japan |
Sector | Public |
PI Contribution | This was a joint application from Daniel Faulkner and Takehiro Hirose (JAMSTEC, Kochi) for funding from the JSPS to allow a research visit to Japan to follow up on some of the work that was discussed during the course of the UKRI grant. |
Collaborator Contribution | The Fellowship is planned for September 2022. |
Impact | No outputs yet. |
Start Year | 2019 |
Description | Herdman Symposium, Liverpool |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Schools |
Results and Impact | Invited talk to the annual Herdman Symposium 2022, a gathering of Schools, general public. We had participants from several countries and 6 invited speakers. |
Year(s) Of Engagement Activity | 2022 |
Description | Radio Interview |
Form Of Engagement Activity | A press release, press conference or response to a media enquiry/interview |
Part Of Official Scheme? | No |
Geographic Reach | Regional |
Primary Audience | Media (as a channel to the public) |
Results and Impact | Interview with Radio Merseyside on the Turkey/Syria earthquake in February 2023. |
Year(s) Of Engagement Activity | 2023 |
URL | https://www.bbc.co.uk/sounds/play/p0dyf1lm |
Description | Radio interview |
Form Of Engagement Activity | A press release, press conference or response to a media enquiry/interview |
Part Of Official Scheme? | No |
Geographic Reach | Regional |
Primary Audience | Media (as a channel to the public) |
Results and Impact | Radio interview with BBC Radio Essex on a small earthquake that occurred near Colchester. |
Year(s) Of Engagement Activity | 2023 |
Description | Talk for the Computational Infrastructure for Geodynamics webinar series, March 10th 2023 |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Postgraduate students |
Results and Impact | I gave a webinar presentation to the Computational Infrastructure for Geodynamics (CIG) research group. The webinar is hosted at the University of Southern California, but is accessible to international CIG community and wider public. A recording of the presentation is also uploaded to YouTube. I presented research findings that were collected during grants NE/S015531/1 and NE/P002943/1. Here is the abstract from my presentation: Geophysical evidence suggests that some faults are frictionally strong, in agreement with laboratory measurements of quasi-static frictional strength (µ ˜ 0.6-0.8) for many crustal materials; whereas others studies have found that some faults are weak when compared to laboratory friction values (µ < 0.5). It has also been well documented that fault materials undergo a significant dynamic reduction in frictional strength when the sliding velocity accelerates to earthquake slip rates (on the order of meters per second). In this talk I will review our current understanding of fault strength evolution during the seismic cycle, then I will present results from two recent laboratory studies where we attempt to elucidate some of the dominant controls on fault strength both before and after an earthquake has occurred. Firstly, I will present results from a study where we investigate how geological heterogeneity in fault zones affects fault strength and stability; we find that heterogeneous faults are considerably weaker and more frictionally unstable than compositionally identical faults with an initially homogeneous structure. Then I will present results from some high-velocity friction experiments where we investigate how faults recover their strength after experiencing dynamic weakening during a seismic slip event. Our findings show that fault strength recovery (healing) occurs rapidly after high-velocity slip, which has important implications for our understanding of rupture dynamics and earthquake recurrence. |
Year(s) Of Engagement Activity | 2023 |
URL | https://www.youtube.com/watch?v=x30lgfpAuho |
Description | Talk to University of the 3rd Age (U3A), Loughborough |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | Regional |
Primary Audience | Public/other audiences |
Results and Impact | ~60 people attended a talk on 'Journey to the Centre of the Earthquake: Drilling for Answers in Japan' to the University of the Third Age, Loughborough, UK, April 2019 |
Year(s) Of Engagement Activity | 2019 |
Description | Talk to the University of the Third Age, Loughborough, UK, November 2021 |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Public/other audiences |
Results and Impact | Talk on 'Carbon capture and storage' to the University of the Third Age, Loughborough, UK, November 2021. ~60 people attended online. |
Year(s) Of Engagement Activity | 2022 |