Professor Stefan Nielsen's Outputs (69)

Electrical resistivity tomography of a masonry bridge: assessing water infiltration on Prebends bridge, Durham, UK (2024)
Journal Article
Jones, L., Jenkins, J., Foltier, L., & Nielsen, S. (2024). Electrical resistivity tomography of a masonry bridge: assessing water infiltration on Prebends bridge, Durham, UK. Journal of Architectural Conservation, https://doi.org/10.1080/13556207.2024.2357501

Non-invasive imaging methods are a useful tool in informing conservation actions for historical buildings. Electrical Resistivity Tomography (ERT) is widely used in geophysics to image the subsurface but has been seldom used for non-invasive imaging... Read More about Electrical resistivity tomography of a masonry bridge: assessing water infiltration on Prebends bridge, Durham, UK.

Fracture Energy and Breakdown Work During Earthquakes (2023)
Journal Article
Cocco, M., Aretusini, S., Cornelio, C., Nielsen, S. B., Spagnuolo, E., Tinti, E., & Di Toro, G. (2023). Fracture Energy and Breakdown Work During Earthquakes. Annual Review of Earth and Planetary Sciences, 51(1), 217-252. https://doi.org/10.1146/annurev-earth-071822-100304

Large seismogenic faults consist of approximately meter-thick fault cores surrounded by hundreds-of-meters-thick damage zones. Earthquakes are generated by rupture propagation and slip within fault cores and dissipate the stored elastic strain energy... Read More about Fracture Energy and Breakdown Work During Earthquakes.

Nucleation of Laboratory Earthquakes: Quantitative Analysis and Scalings (2023)
Journal Article
Marty, S., Schubnel, A., Bhat, H. S., Aubry, J., Fukuyama, E., Latour, S., …Madariaga, R. (2023). Nucleation of Laboratory Earthquakes: Quantitative Analysis and Scalings. Journal of Geophysical Research. Solid Earth, 128(3), Article e2022JB026294. https://doi.org/10.1029/2022jb026294

In this study we use the precursory acoustic emission (AE) activity during the nucleation of stick-slip instability as a proxy to investigate foreshock occurrence prior to natural earthquakes. We report on three stick-slip experiments performed on cy... Read More about Nucleation of Laboratory Earthquakes: Quantitative Analysis and Scalings.

Frictional power dissipation in a seismic ancient fault (2023)
Journal Article
Lazari, F., Castagna, A., Nielsen, S., Griffith, A., Pennacchioni, G., Gomila, R., Resor, P., Cornelio, C., & Di Toro, G. (2023). Frictional power dissipation in a seismic ancient fault. Earth and Planetary Science Letters, 607, Article 118057. https://doi.org/10.1016/j.epsl.2023.118057

Determination of Parameters Characteristic of Dynamic Weakening Mechanisms During Seismic Faulting in Cohesive Rocks (2022)
Journal Article
Cornelio, C., Spagnuolo, E., Aretusini, S., Nielsen, S., Passelègue, F., Violay, M., Cocco, M., & Di Toro, G. (2022). Determination of Parameters Characteristic of Dynamic Weakening Mechanisms During Seismic Faulting in Cohesive Rocks. Journal of Geophysical Research. Solid Earth, 127(7), https://doi.org/10.1029/2022jb024356

While sliding at seismic slip-rates of ∼1 m/s, natural faults undergo an abrupt decrease of shear stress called dynamic weakening. Asperity-scale (<<mm) processes related to flash heating and weakening and, meso-scale (mm-cm) processes involving shea...

Coseismic fault lubrication by viscous deformation (2021)
Journal Article
Pozzi, G., De Paola, N., Nielsen, S., Holdsworth, R., Tesei, T., Thieme, M., & Demouchy, S. (2021). Coseismic fault lubrication by viscous deformation. Nature Geoscience, 14(6), 437-442. https://doi.org/10.1038/s41561-021-00747-8

Despite the hazard posed by earthquakes, we still lack fundamental understanding of the processes that control fault lubrication behind a propagating rupture front and enhance ground acceleration. Laboratory experiments show that fault materials dram... Read More about Coseismic fault lubrication by viscous deformation.

Thermal weakening friction during seismic slip experiments and models with heat sources and sinks (2021)
Journal Article
Nielsen, S., Spagnuolo, E., Violay, M., & Di Toro, G. (2021). Thermal weakening friction during seismic slip experiments and models with heat sources and sinks. Journal of Geophysical Research. Solid Earth, 126(5), Article e2020JB020652. https://doi.org/10.1029/2020jb020652

Experiments that systematically explore rock friction under crustal earthquake conditions reveal that faults undergo abrupt dynamic weakening. Processes related to heating and weakening of fault surfaces have been invoked to explain pronounced veloci... Read More about Thermal weakening friction during seismic slip experiments and models with heat sources and sinks.

Scaling Seismic Fault Thickness From the Laboratory to the Field (2021)
Journal Article
Ferrand, T. P., Nielsen, S., Labrousse, L., & Schubnel, A. (2021). Scaling Seismic Fault Thickness From the Laboratory to the Field. Journal of Geophysical Research. Solid Earth, 126(3), Article e2020JB020694. https://doi.org/10.1029/2020jb020694

Pseudotachylytes originate from the solidification of frictional melt, which transiently forms and lubricates the fault plane during an earthquake. Here, we observe how the pseudotachylyte thickness a scales with the relative displacement D both at t... Read More about Scaling Seismic Fault Thickness From the Laboratory to the Field.

The Humbly Grove, Herriard and Hester’s Copse Fields, UK onshore (2020)
Journal Article
Gluyas, J., De-Paola, N., Imber, J., Jezierski, T., Jones, R., Jordan, P., McCaffrey, K., Nielsen, S., Pongthunya, P., Satterley, A., Sowter, A., Wilkinson, M., & Moors, A. (2020). The Humbly Grove, Herriard and Hester’s Copse Fields, UK onshore. Memoirs, 52, 74-81. https://doi.org/10.1144/m52-2018-78

The Humbly Grove Field has, for the UK, a unique development history. It was discovered as an oilfield in May 1980 and produced as an oilfield until 2000 along with small satellite fields Herriard (developed) and Hester's Copse (not developed). Peak... Read More about The Humbly Grove, Herriard and Hester’s Copse Fields, UK onshore.

A bigger splat: The catastrophic geology of a 1.2-b.y.-old terrestrial megaclast, northwest Scotland (2020)
Journal Article
Killingback, Z., Holdsworth, R., Walker, R., Nielsen, S., Dempsey, E., & Hardman, K. (2020). A bigger splat: The catastrophic geology of a 1.2-b.y.-old terrestrial megaclast, northwest Scotland. Geology, 49(2), 180-184. https://doi.org/10.1130/g48079.1

Rockfalls are relatively little described from the ancient geological record, likely due to their poor preservation potential. At Clachtoll, northwest Scotland, a megaclast (100 m × 60 m × 15 m) of Neoarchean Lewisian gneiss with an estimated mass of... Read More about A bigger splat: The catastrophic geology of a 1.2-b.y.-old terrestrial megaclast, northwest Scotland.

Storage Coefficients and Permeability Functions for Coal-Bed Methane Production Under Uniaxial Strain Conditions (2019)
Journal Article
Mathias, S. A., Nielsen, S., & Ward, R. L. (2019). Storage Coefficients and Permeability Functions for Coal-Bed Methane Production Under Uniaxial Strain Conditions. Transport in Porous Media, 130(2), 627-636. https://doi.org/10.1007/s11242-019-01331-w

The porosity and permeability of coal change with pore pressure, due to changes in effective stress and matrix swelling due to gas adsorption. Three analytical models to describe porosity and permeability change in this context have been presented in... Read More about Storage Coefficients and Permeability Functions for Coal-Bed Methane Production Under Uniaxial Strain Conditions.

Coseismic ultramylonites: An investigation of nanoscale viscous flow and fault weakening during seismic slip (2019)
Journal Article
Pozzi, G., De Paola, N., Holdsworth, R. E., Bowen, L., Nielsen, S. B., & Dempsey, E. D. (2019). Coseismic ultramylonites: An investigation of nanoscale viscous flow and fault weakening during seismic slip. Earth and Planetary Science Letters, 516, 164-175. https://doi.org/10.1016/j.epsl.2019.03.042

Faults weaken during the propagation of earthquakes due to the onset of thermally-activated mechanisms, which vary depending on the rock type. Recent experimental work suggests that carbonate-hosted faults are lubricated by viscous flow in nano-granu... Read More about Coseismic ultramylonites: An investigation of nanoscale viscous flow and fault weakening during seismic slip.

Mechanical behaviour of fluid-lubricated faults (2019)
Journal Article
Cornelio, C., Spagnuolo, E., Di Toro, G., Nielsen, S., & Violay, M. (2019). Mechanical behaviour of fluid-lubricated faults. Nature Communications, 10, Article 1274. https://doi.org/10.1038/s41467-019-09293-9

Fluids are pervasive in fault zones cutting the Earth's crust; however, the effect of fluid viscosity on fault mechanics is mainly conjectured by theoretical models. We present friction experiments performed on both dry and fluid-permeated silicate a... Read More about Mechanical behaviour of fluid-lubricated faults.

Closed-form equation for subsidence due to fluid production from a cylindrical confined aquifer (2019)
Journal Article
Jayeoba, A., Mathias, S. A., Nielsen, S., Vilarrasa, V., & Bjørnarå, T. I. (2019). Closed-form equation for subsidence due to fluid production from a cylindrical confined aquifer. Journal of Hydrology, 573, 964-969. https://doi.org/10.1016/j.jhydrol.2019.03.041

Ground surface subsidence due to groundwater production is a significant problem. Many attempts have been made to develop analytical models to forecast subsidence rates as a consequence of groundwater production. Previous analytical solutions either... Read More about Closed-form equation for subsidence due to fluid production from a cylindrical confined aquifer.

A new interpretation for the nature and significance of mirror-like surfaces in experimental carbonate-hosted seismic faults (2018)
Journal Article
Pozzi, G., De Paola, N., Nielsen, S., Holdsworth, R., & Bowen, L. (2018). A new interpretation for the nature and significance of mirror-like surfaces in experimental carbonate-hosted seismic faults. Geology, 46(7), 583-586. https://doi.org/10.1130/g40197.1

Highly reflective, continuous smooth surfaces, known as "mirror-like surfaces" (MSs), have been observed in experimental carbonate-hosted faults, which were sheared at both seismic and aseismic velocities. MSs produced during high-velocity friction e... Read More about A new interpretation for the nature and significance of mirror-like surfaces in experimental carbonate-hosted seismic faults.

Tsunamigenic earthquake simulations using experimentally derived friction laws (2018)
Journal Article
Murphy, S., Di Toro, G., Romano, F., Scala, A., Lorito, S., Spagnuolo, E., Aretusini, S., Festa, G., Piatanesi, A., & Nielsen, S. (2018). Tsunamigenic earthquake simulations using experimentally derived friction laws. Earth and Planetary Science Letters, 486, 155-165. https://doi.org/10.1016/j.epsl.2018.01.011

Seismological, tsunami and geodetic observations have shown that subduction zones are complex systems where the properties of earthquake rupture vary with depth as a result of different pre-stress and frictional conditions. A wealth of earthquakes of... Read More about Tsunamigenic earthquake simulations using experimentally derived friction laws.

Earthquake Nucleation Size: Evidence of Loading Rate Dependence in Laboratory Faults (2018)
Journal Article
Guérin‐Marthe, S., Nielsen, S., Bird, R., Giani, S., & Di Toro, G. (2018). Earthquake Nucleation Size: Evidence of Loading Rate Dependence in Laboratory Faults. Journal of Geophysical Research. Solid Earth, 124(1), 689-708. https://doi.org/10.1029/2018jb016803

Recent GPS observations of major earthquakes such as the 2014 Chile megathrust show a slow pre‐slip phase releasing a significant portion of the total moment (Ruiz et al., 2014). Despite advances from theoretical stability analysis (Rubin & Ampuero,... Read More about Earthquake Nucleation Size: Evidence of Loading Rate Dependence in Laboratory Faults.

Past seismic slip-to-the-trench recorded in Central America megathrust (2017)
Journal Article
Vannucchi, P., Spagnuolo, E., Aretusini, S., Di Toro, G., Ujiie, K., Tsutsumi, A., & Nielsen, S. (2017). Past seismic slip-to-the-trench recorded in Central America megathrust. Nature Geoscience, 10(12), 935-940. https://doi.org/10.1038/s41561-017-0013-4

The 2011 Tōhoku-Oki earthquake revealed that co-seismic displacement along the plate boundary megathrust can propagate to the trench. Co-seismic slip to the trench amplifies hazards at subduction zones, so its historical occurrence should also be inv... Read More about Past seismic slip-to-the-trench recorded in Central America megathrust.

From slow to fast faulting: recent challenges in earthquake fault mechanics (2017)
Journal Article
Nielsen, S. (2017). From slow to fast faulting: recent challenges in earthquake fault mechanics. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 375(2103), Article 20160016. https://doi.org/10.1098/rsta.2016.0016

Faults—thin zones of highly localized shear deformation in the Earth—accommodate strain on a momentous range of dimensions (millimetres to hundreds of kilometres for major plate boundaries) and of time intervals (from fractions of seconds during eart... Read More about From slow to fast faulting: recent challenges in earthquake fault mechanics.

Earthquake nucleation on rough faults (2017)
Journal Article
Harbord, C. W., Nielsen, S. B., De Paola, N., & Holdsworth, R. E. (2017). Earthquake nucleation on rough faults. Geology, 45(10), 931-934. https://doi.org/10.1130/g39181.1

Earthquake nucleation is currently explained using rate and state stability analysis, which successfully models the behavior of laboratory simulated faults with constant thickness gouge layers. However, roughness is widely observed on natural faults... Read More about Earthquake nucleation on rough faults.