Professor Sandy Steacy

Professor Sandy Steacy

Head of School

School of Environmental and Life Sciences

Career Summary

Biography

I'm a geophysicist with a broad background in fundamental geology, rock mechanics, and earthquake physics. I completed my undergraduate degree in geology at the University of North Carolina at Chapel Hill where I mainly focused on hard rock petrology, structural geology, tectonics, and geophysics.

I then did a PhD in geophysics at the University of Southern California. Postgraduate research degrees in the US require coursework and I studied structural petrology, advanced field mapping, and geodynamics as well as seismology, rock mechanics, and advanced mathematics. I also developed a variety of research skills, initially in seismology with Professor Kei Aki, and subsequently in rock mechanics and numerical modelling with Professor Charlie Sammis. My PhD thesis - 'Fractal Fragmentation in Fault Zones' - included research that I published in Nature and in the Journal of Geophysical Research. During that time period I also undertook short term industry employment at Arco Oil and Gas and the California Office of Emergency Services.

After a brief period as a postdoc at USC, I moved to the University of Ulster in Northern Ireland for a 2 year research position modelling mining induced seismicity. The project involved developing statistical numerical models to assess the likely effects of different mining processes on earthquake distributions in Creighton Mine in Sudbury, northern Ontario. The project was extended for a further 2 years and I was subsequently appointed to a research lecturer position at the university.

My research interests changed after this appointment and with a senior colleague I co-led a European Framework V project on the influence of co-seismic (Coulomb) stress changes on aftershock timings and locations. The project involved partners in Italy, Greece, France, Scotland, and the Czech Republic; one significant result was that these stress changes could be computed rapidly enough to inform short term (conditional) seismic hazard. We put this into practice following the 2004 Sumatra earthquake, publishing a paper in Nature suggesting the likelihood of subsequent large events in the region. As it turned out, the M=8.7 Nias earthquake occurred in our region of concern shortly afterwards.

I next became involved in tsunami modelling with colleagues in the UK, Italy, Indonesia, and the US. We developed a novel approach to the earthquake source model with 4 different rupture length scenarios and 25 realistic fractal slip distributions per scenario. We found a linear relationship between co-seismic coastal elevation change and maximum tsunami wave height and published a suite of possible tsunami wave heights that could impact Indonesia and Australia. Subsequently I worked with colleagues at GNS Science in New Zealand to model earthquake triggering in the Canterbury sequence and to develop a new model for operational earthquake forecasting. I was also a member of the Expert Elicitation Panel whose work informed the revision of building codes in Canterbury.

In addition to further work on earthquake forecasting, I currently work with colleagues at Melbourne University on earthquake triggering in Australian sequences. I am also beginning a new collaboration with New Zealand colleagues as part of a major project they are leading to develop a revised seismic hazard map for the country. In 2016 I was an expert witness on earthquake safety for the Citizens' Jury on the Nuclear Fuel Cycle and I did some consulting research on the earthquake hazard associated with the proposed radioactive waste disposal facility.

My first formal leadership role was as Director of the Environmental Sciences Research Institute at the University of Ulster. In this role I contributed strongly to the University's impact submission to the first REF, and I led successful Institute and University initiatives to increase our grant income from highly competitive funders such as Research Councils. I was also a member of the peer review college of the Natural Environment Research Council and of funding panels for Science Foundation Ireland and the European Commission.

I moved to Adelaide in 2015 to become the inaugural Head of the School of Physical Sciences. This strongly research intensive School includes the disciplines of chemistry, earth science, and physics. In ERA 2018, physics maintained its score of straight 5s, chemistry improved to straight 5s, and earth science improved to a 5 at two digit level. In addition, I led the University's impact and engagement submission to ERA 2018, I was a member of the physical sciences and engineering assessment panel for Engagement and Impact in ERA, and I was a member of the ARC College of Experts.


Qualifications

  • Doctor of Philosophy, University of Southern California
  • Bachelor of Science (Geology), University of North Carolina, Chapel Hill

Keywords

  • earthquakes
  • geophysics
  • natural hazards
  • seismic hazard
  • tsunamis

Fields of Research

Code Description Percentage
040402 Geodynamics 20
040499 Geophysics not elsewhere classified 20
040407 Seismology and Seismic Exploration 60

Professional Experience

UON Appointment

Title Organisation / Department
Head of School University of Newcastle
School of Environmental and Life Sciences
Australia

Academic appointment

Dates Title Organisation / Department
1/11/2009 - 31/12/2014 Director The University of Ulster
Environmental Sciences Research Institute
United Kingdom
1/10/2007 - 31/12/2014 Professor of Earthquake Physics The University of Ulster
United Kingdom
1/1/2015 - 3/11/2019 Head of School The University of Adelaide
Physical Sciences
Australia
Edit

Publications

For publications that are currently unpublished or in-press, details are shown in italics.


Journal article (30 outputs)

Year Citation Altmetrics Link
2019 Mohammadi H, Quigley M, Steacy S, Duffy B, 'Effects of source model variations on Coulomb stress analyses of a multi-fault intraplate earthquake sequence', TECTONOPHYSICS, 766 151-166 (2019)
DOI 10.1016/j.tecto.2019.06.007
Citations Scopus - 3Web of Science - 2
2018 Cattania C, Werner MJ, Marzocchi W, Hainzl S, Rhoades D, Gerstenberger M, et al., 'The forecasting skill of physics-based seismicity models during the 2010-2012 canterbury, New Zealand, earthquake sequence', Seismological Research Letters, 89 1238-1250 (2018)

© 2018 Seismological Society of America. All rights reserved. The static coulomb stress hypothesis is a widely known physical mechanism for earthquake triggering and thus a prime ... [more]

© 2018 Seismological Society of America. All rights reserved. The static coulomb stress hypothesis is a widely known physical mechanism for earthquake triggering and thus a prime candidate for physics-based operational earthquake forecasting (OEF). However, the forecast skill of coulomb-based seismicity models remains controversial, especially compared with empirical statistical models. A previous evaluation by the Collaboratory for the Study of Earthquake Predictability (CSEP) concluded that a suite of coulomb-based seismicity models were less informative than empirical models during the aftershock sequence of the 1992 Mw 7.3 Landers, California, earthquake. Recently, a new generation of coulomb-based and coulomb/statistical hybrid models were developed that account better for uncertainties and secondary stress sources. Here, we report on the performance of this new suite of models compared with empirical epidemic-type aftershock sequence (ETAS) models during the 2010-2012 Canterbury, New Zealand, earthquake sequence. Comprising the 2010 M 7.1 Darfield earthquake and three subsequent M = 5:9 shocks (including the February 2011 Christchurch earthquake), this sequence provides a wealth of data (394 M = 3:95 shocks). We assessed models over multiple forecast horizons (1 day, 1 month, and 1 yr, updated after M = 5:9 shocks). The results demonstrate substantial improvements in the coulomb-based models. Purely physics-based models have a performance comparable to the ETAS model, and the two coulomb/statistical hybrids perform better or similar to the corresponding statistical model. On the other hand, an ETAS model with anisotropic (fault-based) aftershock zones is just as informative. These results provide encouraging evidence for the predictive power of coulomb-based models. To assist with model development, we identify discrepancies between forecasts and observations.

DOI 10.1785/0220180033
Citations Scopus - 14Web of Science - 15
2018 Reverso T, Steacy S, Marsan D, 'A Hybrid ETAS-Coulomb Approach to Forecast Spatiotemporal Aftershock Rates', Journal of Geophysical Research: Solid Earth, 123 9750-9763 (2018)

©2018. American Geophysical Union. All Rights Reserved. Aftershock sequences are an ideal testing ground for operational earthquake forecasting models as they contain relatively l... [more]

©2018. American Geophysical Union. All Rights Reserved. Aftershock sequences are an ideal testing ground for operational earthquake forecasting models as they contain relatively large numbers of earthquakes clustered in time and space. To date, most successful forecast models have been statistical, building on empirical observations of aftershock decay with time and earthquake size frequency distributions. Another approach is to include Coulomb stress changes from the mainshock which influence the spatial location of the aftershocks although these models have generally not performed as well as the statistical ones. Here we develop a new hybrid Epidemic-Type Aftershock Sequence (ETAS)/Coulomb model which attempts to overcome the limitations of its predecessors by redistributing forecast rate from negatively to positively stressed regions based on observations in the model learning period of the percentage of events occurring in those positively stressed regions. We test this model against the 1992 Landers aftershock sequence using three different ETAS kernels and five different models for slip in the Landers earthquake. We also consider two variations of rate redistribution, one based on a fixed value and the other variable depending on the percentage of aftershocks observed in positively stressed Coulomb regions during the learning period. We find that the latter model performs at least as well as ETAS on its own in all tests and better than ETAS in 14 of 15 tests in which we forecast successive 24-hr periods. Our results suggest that including Coulomb stress changes can improve operational earthquake forecasting models.

DOI 10.1029/2017JB015108
2016 Sunbul F, Nalbant SS, Simão NM, Steacy S, 'Investigating viscoelastic postseismic deformation due to large earthquakes in East Anatolia, Turkey', Journal of Geodynamics, 94-95 50-58 (2016)

© 2016 Elsevier Ltd. We investigate the postseismic viscoelastic flow in the lower crust and upper mantle due to the 19th and 20th century large earthquakes in eastern Turkey. Thr... [more]

© 2016 Elsevier Ltd. We investigate the postseismic viscoelastic flow in the lower crust and upper mantle due to the 19th and 20th century large earthquakes in eastern Turkey. Three possible rheological models are used in the viscoelastic postseismic deformation analysis to assess the extent to which these events influence the velocity fields at GPS sites in the region. Our models show that the postseismic signal currently contributes to the observed deformation in the eastern part of the North Anatolian fault and northern and middle parts of the East Anatolian Fault Zone, primarily due to the long-lasting effect of the Ms 7.9 1939 earthquake. None of the postseismic displacement generated by the Ms 7.5 1822 earthquake, which is the earliest and the second largest event in the calculations, exceeds observed error range at the GPS stations. Our results demonstrate that a postseismic signal can be identified in the region and could contribute up to 3-25% of the observed GPS measurements.

DOI 10.1016/j.jog.2016.01.002
Citations Scopus - 2Web of Science - 1
2016 Bucholc M, Steacy S, 'Tidal stress triggering of earthquakes in Southern California', Geophysical Journal International, 205 681-693 (2016)

© The Authors 2016. We analyse the influence of the solid Earth tides and ocean loading on the occurrence time of Southern California earthquakes. For each earthquake, we calculat... [more]

© The Authors 2016. We analyse the influence of the solid Earth tides and ocean loading on the occurrence time of Southern California earthquakes. For each earthquake, we calculate tidal Coulomb failure stress and stress rate on a fault plane that is assumed to be controlled by the orientation of the adjacent fault. To reduce bias when selecting data for testing the tide-earthquake relationship, we create four earthquake catalogues containing events within 1, 1.5, 2.5 and 5 km of nearest faults. We investigate the difference in seismicity rates at times of positive and negative tidal stresses/stress rates given three different cases. We consider seismicity rates during times of positive versus negative stress and stress rate, as well as 2 and 3 hr surrounding the local tidal stress extremes. We find that tidal influence on earthquake occurrence is found to be statistically non-random only in close proximity to tidal extremes meaning that magnitude of tidal stress plays an important role in tidal triggering. A non-random tidal signal is observed for the reverse events. Along with a significant increase in earthquake rates around tidal Coulomb stress maxima, the strength of tidal correlation is found to be closely related to the amplitude of the peak tidal Coulomb stress (t p). The most effective tidal triggering is found for t p = 1 kPa, which is much smaller than thresholds suggested for static and dynamic triggering of aftershocks.

DOI 10.1093/gji/ggw045
Citations Scopus - 4Web of Science - 2
2013 Nalbant S, McCloskey J, Steacy S, Nicbhloscaidh M, Murphy S, 'Interseismic coupling, stress evolution, and earthquake slip on the Sunda megathrust', Geophysical Research Letters, 40 4204-4208 (2013)

The extent to which interseismic coupling controls the slip distribution of large megathrust earthquakes is unclear, with some authors proposing that it is the primary control and... [more]

The extent to which interseismic coupling controls the slip distribution of large megathrust earthquakes is unclear, with some authors proposing that it is the primary control and others suggesting that stress changes from previous earthquakes are of first-order importance. Here, we develop a detailed stress history of the Sunda megathrust, modified by coupling, and compare the correlation between slip and stress with that of slip versus coupling. We find that the slip distributions of recent earthquakes are more consistent with the stress field than with the coupling distributions but observe that in places, the stress pattern is strongly dependent on poorly constrained values of slip in historical earthquakes. We also find that of the 13 earthquakes in our study for which we have hypocentral locations, only two appear to have nucleated in areas of negative stress, and these locations correspond to large uncertainties in the slip distribution of pre-instrumental events. Key Points The stress history of the Sunda Trench is computed from 1797 to present Stress and earthquake slip is better correlated than coupling and slip Better methods of estimating pre-instrumental slip are required. © 2013. American Geophysical Union. All Rights Reserved.

DOI 10.1002/grl.50776
Citations Scopus - 13Web of Science - 14
2013 Steacy S, Jiménez A, Holden C, 'Stress triggering and the canterbury earthquake sequence', Geophysical Journal International, 196 473-480 (2013)

The Canterbury earthquake sequence, which includes the devastating Christchurch event of 2011 February, has to date led to losses of around 40 billion NZ dollars. The location and... [more]

The Canterbury earthquake sequence, which includes the devastating Christchurch event of 2011 February, has to date led to losses of around 40 billion NZ dollars. The location and severity of the earthquakes was a surprise to most inhabitants as the seismic hazard model was dominated by an expected Mw > 8 earthquake on the Alpine fault and an Mw 7.5 earthquake on the Porters Pass fault, 150 and 80 km to the west of Christchurch. The sequence to date has included an Mw = 7.1 earthquake and 3 Mw =5.9 events which migrated from west to east. Here we investigate whether the later events are consistent with stress triggering and whether a simple stress map produced shortly after the first earthquake would have accurately indicated the regions where the subsequent activity occurred. We find that 100 per cent of M > 5.5 earthquakes occurred in positive stress areas computed using a slip model for the first event that was available within 10 d of its occurrence. We further find that the stress changes at the starting points of major slip patches of post-Darfield main events are consistent with triggering although this is not always true at the hypocentral locations. Our results suggest that Coulomb stress changes contributed to the evolution of the Canterbury sequence and we note additional areas of increased stress in the Christchurch region and on the Porters Pass fault. © The Authors 2013. Published by Oxford University Press on behalf of The Royal Astronomical Society.

DOI 10.1093/gji/ggt380
Citations Scopus - 15Web of Science - 16
2013 Steacy S, Gerstenberger M, Williams C, Rhoades D, Christophersen A, 'A new hybrid Coulomb/statistical model for forecasting aftershock rates', Geophysical Journal International, 196 918-923 (2013)

Forecasting the spatial and temporal distribution of aftershocks is of great importance to earthquake scientists, civil protection authorities and the general public as these even... [more]

Forecasting the spatial and temporal distribution of aftershocks is of great importance to earthquake scientists, civil protection authorities and the general public as these events cause disproportionate damage and consternation relative to their size. At present, there are two main approaches to such forecasts-purely statistical methods based on observations of the initial portions of aftershock sequences and a physics-based approach based on Coulomb stress changes caused by the main shock. Here we develop a new method which combines the spatial constraints from the Coulomb model with the statistical power of the STEP (short-term earthquake probability) approach. We test this pseudo prospectively and retrospectively on the Canterbury sequence against the STEP model and a Coulomb rate-state method, using data from the first 10 d following each main event to forecast the rate of M = 4 events in the following 100 d. We find that in retrospective tests the new model outperforms STEP for two events in the sequence but this is not the case for pseudo-prospective tests. Further, the Coulomb rate-state approach never performs better than STEP. Our results suggest that incorporating the physical constraints from Coulomb stress changes can increase the forecasting power of statistical models and clearly show the importance of good data quality if prospective forecasts are to be implemented in practice. © The Authors 2013. Published by Oxford University Press on behalf of The Royal Astronomical Society.

DOI 10.1093/gji/ggt404
Citations Scopus - 23Web of Science - 25
2011 Zechar JD, Hardebeck JL, Michael AJ, Naylor M, Steacy S, Wiemer S, Zhuang J, 'Community online resource for statistical seismicity analysis', Seismological Research Letters, 82 686-690 (2011)
DOI 10.1785/gssrl.82.5.686
Citations Scopus - 4Web of Science - 5
2008 McCloskey J, Antonioli A, Piatanesi A, Sieh K, Steacy S, Nalbant S, et al., 'Tsunami threat in the Indian Ocean from a future megathrust earthquake west of Sumatra', Earth and Planetary Science Letters, 265 61-81 (2008)

Several independent indicators imply a high probability of a great (M > 8) earthquake rupture of the subduction megathrust under the Mentawai Islands of West Sumatra. The human... [more]

Several independent indicators imply a high probability of a great (M > 8) earthquake rupture of the subduction megathrust under the Mentawai Islands of West Sumatra. The human consequences of such an event depend crucially on its tsunamigenic potential, which in turn depends on unpredictable details of slip distribution on the megathrust and how resulting seafloor movements and the propagating tsunami waves interact with bathymetry. Here we address the forward problem by modelling about 1000 possible complex earthquake ruptures and calculating the seafloor displacements and tsunami wave height distributions that would result from the most likely 100 or so, as judged by reference to paleogeodetic data. Additionally we carry out a systematic study of the importance of the location of maximum slip with respect to the morphology of the fore-arc complex. Our results indicate a generally smaller regional tsunami hazard than was realised in Aceh during the December 2004 event, though more than 20% of simulations result in tsunami wave heights of more than 5¿m for the southern Sumatran cities of Padang and Bengkulu. The extreme events in these simulations produce results which are consistent with recent deterministic studies. The study confirms the sensitivity of predicted wave heights to the distribution of slip even for events with similar moment and reproduces Plafker's rule of thumb. Additionally we show that the maximum wave height observed at a single location scales with the magnitude though data for all magnitudes exhibit extreme variability. Finally, we show that for any coastal location in the near field of the earthquake, despite the complexity of the earthquake rupture simulations and the large range of magnitudes modelled, the timing of inundation is constant to first order and the maximum height of the modelled waves is directly proportional to the vertical coseismic displacement experienced at that point. These results may assist in developing tsunami preparedness strategies around the Indian Ocean and in particular along the coasts of western Sumatra. © 2007 Elsevier B.V. All rights reserved.

DOI 10.1016/j.epsl.2007.09.034
Citations Scopus - 77Web of Science - 64
2007 McCloskey J, Antonioli A, Piatanesi A, Sieh K, Steacy S, Nalbant SS, et al., 'Near-field propagation of tsunamis from megathrust earthquakes', Geophysical Research Letters, 34 (2007)

We investigate controls on tsunami generation and propagation in the near-field of great megathrust earthquakes using a series of numerical simulations of subduction and tsunamige... [more]

We investigate controls on tsunami generation and propagation in the near-field of great megathrust earthquakes using a series of numerical simulations of subduction and tsunamigenesis on the Sumatran forearc. The Sunda megathrust here is advanced in its seismic cycle and may be ready for another great earthquake. We calculate the seafloor displacements and tsunami wave heights for about 100 complex earthquake ruptures whose synthesis was informed by reference to geodetic and stress accumulation studies. Remarkably, results show that, for any near-field location: (1) the timing of tsunami inundation is independent of slip-distribution on the earthquake or even of its magnitude, and (2) the maximum wave height is directly proportional to the vertical coseismic displacement experienced at that location. Both observations are explained by the dominance of long wavelength crustal flexure in near-field tsunamigenesis. The results show, for the first time, that a single estimate of vertical coseismic displacement might provide a reliable short-term forecast of the maximum height of tsunami waves. Copyright 2007 by the American Geophysical Union.

DOI 10.1029/2007GL030494
Citations Scopus - 17Web of Science - 18
2007 Hetherington A, Steacy S, 'Fault heterogeneity and earthquake scaling', Geophysical Research Letters, 34 (2007)

There is an on-going debate in the seismological community as to whether stress drop is independent of earthquake size and this has important implications for earthquake physics. ... [more]

There is an on-going debate in the seismological community as to whether stress drop is independent of earthquake size and this has important implications for earthquake physics. Here we investigate this question in a simple 2D cellular automaton that includes heterogeneity. We find that when the range of heterogeneity is low, the scaling approaches that of constant stress drop. However, clear deviations from the constant stress drop model are observed when the range of heterogeneity is large. Further, fractal distributions of strength show more significant departures from constant scaling than do random ones. Additionally, sub-sampling the data over limited magnitude ranges can give the appearance of constant stress drop even when the entire data set does not support this. Our results suggest that deviations from constant earthquake scaling are real and reflect the heterogeneity of natural fault zones, but may not provide much information about the physics of earthquakes. Copyright 2007 by the American Geophysical Union.

DOI 10.1029/2007GL030365
Citations Scopus - 2Web of Science - 2
2006 Nalbant SS, Steacy S, Mccloskey J, 'Stress transfer relations among the earthquakes that occurred in Kerman province, southern Iran since 1981', Geophysical Journal International, 167 309-318 (2006)

We explore the possible stress triggering relationship of the M = 6.4 earthquakes that occurred in Kerman Province, southern Iran since 1981. We calculated stress changes due to b... [more]

We explore the possible stress triggering relationship of the M = 6.4 earthquakes that occurred in Kerman Province, southern Iran since 1981. We calculated stress changes due to both coseismic sudden movement in the upper crust and the time-dependent viscous relaxation of the lower crust and/or upper mantle following the event. Four events of M = 6.4 occurred between 1981 and 2005, on and close to the Gowk fault, show a clear Coulomb stress load to failure relationship. The 2003 M = 6.5 Bam earthquake, however, which occurred approximately 95 km SW of the closest Gowk event, shows a very weak stress relation to preceding earthquakes. The coseismic static stress change at the hypocentre of the Bam earthquake is quite small (~0.006 bars). The time-dependent post-seismic stress change could be 26 times larger or 7 times lower than that of coseismic static stress alone depending on the choice of viscoelastic crustal model and the effective coefficient of friction. Given the uncertainties in the viscoelastic earth models and the effective coefficient of friction, we cannot confidently conclude that the 2003 Bam event was brought closer to failure through coseismic or post-seismic stress loading. Interestingly, the southern Gowk segment with a similar strike to that of the Bam fault, experienced a stress load of up to 8.3 bars between 1981 and 2003, and is yet to have a damaging earthquake. © 2006 The Authors Journal compilation © 2006 RAS.

DOI 10.1111/j.1365-246X.2006.03119.x
Citations Scopus - 23Web of Science - 20
2005 Nalbant SS, McCloskey J, Steacy S, 'Lessons on the calculation of static stress loading from the 2003 Bingol, Turkey earthquake', Earth and Planetary Science Letters, 235 632-640 (2005)

The 2003 Bingol earthquake (Mw = 6.4) occurred very close to a region along the east Anatolian fault zone which was identified in 2002 as posing a particularly high seismic risk. ... [more]

The 2003 Bingol earthquake (Mw = 6.4) occurred very close to a region along the east Anatolian fault zone which was identified in 2002 as posing a particularly high seismic risk. This damaging earthquake occurred on a conjugate right-lateral blind fault that was inconsistent with the stress-change field calculated for preceding large earthquakes in the region. In this paper, four reasons which might be responsible for this stress discrepancy are identified and investigated individually. Firstly, co-seismic stress changes are considered. The time frame of the previous stress calculations is extended to include the large earthquakes in the 1780s which were not included in the earlier study. A sensitivity analysis is then conducted on the more recent events since 1822 to examine the effect of errors in their location and sizes. The possibility of the occurrence of a small magnitude event close to the 2003 epicentre is considered. We argue that, barring the occurrence of a low-probability, unmodelled local event, the Bingol earthquake was unlikely to have been triggered by co-seismic stress transfer from any known sequence of previous earthquakes. Finally we examine and modify the secular loading model used in the 2002 study and show that loading which is properly constrained by regional GPS data produces a positive stress change on the 2003 rupture. As a result of our examination of the stressing history of the Bingol hypocentre we argue that it is through a combination of historical seismology, guided and constrained by structural geology, directed paleoseismology in which the locations and extent of historical events are confirmed, and stress modelling which has been informed by detailed GPS data, that an integrated seismic hazard program might have the best chance of success. © 2005 Elsevier B.V. All rights reserved.

DOI 10.1016/j.epsl.2005.04.036
Citations Scopus - 8Web of Science - 6
2005 McCloskey J, Nalbant SS, Steacy S, 'Earthquake risk from co-seismic stress', Nature, 434 291 (2005)
DOI 10.1038/434291a
Citations Scopus - 165Web of Science - 138
2005 Nalbant SS, Steacy S, Sieh K, Natawidjaja D, McCloskey J, 'Seismology: Earthquake risk on the Sunda trench', Nature, 435 756-757 (2005)
DOI 10.1038/nature435756a
Citations Scopus - 121Web of Science - 112
2005 Steacy S, Gomberg J, Cocco M, 'Introduction to special section: Stress transfer, earthquake triggering, and time-dependent seismic hazard', Journal of Geophysical Research: Solid Earth, 110 1-12 (2005)

In this introduction, we review much of the recent work related to stress transfer, earthquake triggering, and time-dependent seismic hazard in order to provide context for the sp... [more]

In this introduction, we review much of the recent work related to stress transfer, earthquake triggering, and time-dependent seismic hazard in order to provide context for the special section on these subjects. Considerable advances have been, made in the past decade, and we we focus on our understanding of stress transfer at various temporal and spatial scales, review recent studies of the role of fluids in earthquake triggering, describe evidence for the connection between volcanism and earthquake triggering, examine observational evidence for triggering at all scales, and finally discuss the link between earthquake triggering and time-dependent seismic hazard. We conclude by speculating on future areas of research in the next decade. Copyright 2005 by the American Geophysical Union.

DOI 10.1029/2005JB003692
Citations Scopus - 176Web of Science - 149
2005 Steacy S, Nalbant SS, McCloskey J, Nostro C, Scotti O, Baumont D, 'Onto what planes should Coulomb stress perturbations be resolved?', Journal of Geophysical Research: Solid Earth, 110 1-14 (2005)

Coulomb stress maps are produced by computing the tensorial stress perturbation due to an earthquake rupture and resolving this tensor onto planes of a particular orientation. It ... [more]

Coulomb stress maps are produced by computing the tensorial stress perturbation due to an earthquake rupture and resolving this tensor onto planes of a particular orientation. It is often assumed that aftershock fault planes are "optimally oriented"; in other words, the regional stress and coseismic stress change are used to compute the orientation of planes most likely to fail and the coseismic stress is resolved onto these orientations. This practice assumes that faults capable of sustaining aftershocks exist at all orientations, an assumption contradicted by the observation that aftershock focal mechanisms have strong preferred orientations consistent with mapped structural trends. Here we systematically investigate the best planes onto which stress should be resolved for the Landers, Hector Mine, Loma Prieta, and Northridge earthquakes by quantitatively comparing observed aftershock distributions with stress maps based on optimally oriented planes (two- and three-dimensional), main shock orientation and regional structural trend. We find that the best model differs between different tectonic regions but that in all cases, models that incorporate the regional stress field tend to produce stress maps that best fit the observed aftershock distributions, although not all such models do so equally well. Our results suggest that when the regional stress field is poorly defined, or in structurally complex areas, the best model may be to fix the strike of the planes upon which the stress is to be resolved to that of the main shock but allow the dip and rake to vary. Copyright 2005 by the American Geophysical Union.

DOI 10.1029/2004JB003356
Citations Scopus - 47Web of Science - 45
2004 Steacy S, Marsan D, Nalbant SS, McCloskey J, 'Sensitivity of static stress calculations to the earthquake slip distribution', Journal of Geophysical Research: Solid Earth, 109 (2004)

The apparent strong correlation between Coulomb stress changes and the spatial distribution of aftershocks suggests the possibility of making near-real-time estimations of areas a... [more]

The apparent strong correlation between Coulomb stress changes and the spatial distribution of aftershocks suggests the possibility of making near-real-time estimations of areas at risk of experiencing off-fault aftershocks. In order to do this in practice a number of issues must first be addressed, including the extent to which the main shock slip must be known in detail before a meaningful stress map can be constructed. Here we investigate this issue by constructing a time-ordered sequence of slip solutions for the Landers earthquake, computing Coulomb stress changes for each solution, and quantitatively comparing the stress field with the observed aftershocks by (1) resolving the Coulomb stress change onto the aftershock nodal planes and calculating the percentage of events consistent with triggering and (2) constructing a two-dimensional map of Coulomb stress and computing the correlation coefficient between the positive and negative areas and the locations of the aftershocks. We find that slip solutions based on empirical relations and either focal mechanism or moment tensor data produce stress fields inconsistent with the observed spatial distribution of aftershocks, whereas slip solutions incorporating the correct rupture geometry but greatly simplified slip produce stress fields consistent with the aftershock distribution when very near-fault events are excluded. We further find that resolving stress perturbations onto earthquake nodal planes and computing the percentage of events experiencing positive Coulomb stress provides a poor measure of success because of the limited range of structures on which events occur and the compatibility of the main shock stress field with these structures. Our results support the hypothesis that Coulomb stress changes affect the spatial distribution of aftershocks and suggest that meaningful calculations of Coulomb stress can be made as soon as an earthquake's rupture geometry is well constrained. Copyright 2004 by the American Geophysical Union.

DOI 10.1029/JB002365
Citations Scopus - 60
2004 Steacy S, Marsan D, Nalbant SS, McCloskey J, 'Sensitivity of static stress calculations to the earthquake slip distribution', JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH, 109 (2004)
DOI 10.1029/2002JB002365
Citations Web of Science - 60
2003 McCloskey J, Nalbant SS, Steacy S, Nostro C, Scotti O, Baumont D, 'Structural constraints on the spatial distribution of aftershocks', Geophysical Research Letters, 30 (2003)

Calculations of static stress changes due to large earthquakes have shown that the spatial distribution of aftershocks is predictable to first order, with aftershocks primarily oc... [more]

Calculations of static stress changes due to large earthquakes have shown that the spatial distribution of aftershocks is predictable to first order, with aftershocks primarily occurring in areas experiencing positive stress changes. Delineation of these areas relies on resolving the stress perturbation onto planes with known orientations; common practice is to use poorly constrained regional stress information to compute optimally oriented failure planes, assuming that they exist everywhere. Here we show that this assumption is not supported by observation but rather that aftershock failure planes are controlled by geological structure. We argue that useful aftershock hazard estimates are better made by replacing information on regional stress with statistical measures of structural orientations.

DOI 10.1029/2003GL017225
Citations Scopus - 51Web of Science - 52
2003 Utkucu M, Nalbant SS, McCloskey J, Steacy S, Alptekin O, 'Slip distribution and stress changes associated with the 1999 November 12, Düzce (Turkey) earthquake (M

The 1999 November 12 Düzce earthquake (Mw = 7.1) was apparently the eastward extension of the August 17, Izmit earthquake (Mw = 7.4). The Düzce event caused heavy damage and fatal... [more]

The 1999 November 12 Düzce earthquake (Mw = 7.1) was apparently the eastward extension of the August 17, Izmit earthquake (Mw = 7.4). The Düzce event caused heavy damage and fatalities in the cities of Düzce and Bolu. Here a finite-fault inversion method with five discrete time windows is applied to derive the co-seismic slip distribution of the Düzce earthquake. The fault plane is best modelled as a 40 × 20 km2 plane, with a strike of 262° and a dip of 65° to the north, and that the majority of slip occurred in two distinct patches on either side of the hypocentre, implying bilateral rupture. The possible triggering of this event by the Izmit earthquake is investigated using Coulomb stress modelling of all large events since 1943 with the inclusion of secular loading. The results show that although the Düzce rupture plane was in a stress shadow prior to the Izmit earthquake, that event caused a significant Coulomb stress load, taking the Düzce fault out of the stress shadow, which probably precipitated failure. A comparison of the mapped Coulomb stress change with the inferred slip shows no correlation between the two. Finally, the stress modelling indicates that the northern branch of the North Anatolian fault zone, beneath the Sea of Marmara towards the city of Istanbul, is presently the most highly loaded segment of the North Anatolian Fault Zone.

DOI 10.1046/j.1365-246X.2003.01904.x
Citations Scopus - 36Web of Science - 37
2002 Nalbant SS, McCloskey J, Steacy S, Barka AA, 'Stress accumulation and increased seismic risk in Eastern Turkey', Earth and Planetary Science Letters, 195 291-298 (2002)

Unlike the North Anatolian fault zone, which has produced 11 large earthquakes since 1939, the East Anatolian fault zone (EAFZ) has been relatively quiescent in the last century w... [more]

Unlike the North Anatolian fault zone, which has produced 11 large earthquakes since 1939, the East Anatolian fault zone (EAFZ) has been relatively quiescent in the last century when compared to historical records and has therefore accumulated significant stresses along its length. Determination of the location and likely magnitude of a future probable earthquake along the EAFZ is of interest both because of this history of large earthquakes, (M ¿ 8), and the density of population in the area. Here we calculate stress evolution along the fault zone due to both seismic and tectonic loading since 1822. A sequence of 10 well constrained historical earthquakes is selected and the resulting stresses are calculated, summed with tectonic loading stresses and resolved onto the mapped active faults. We identify two areas of particular seismic risk, one of which might be expected to yield a large event. Our results are sensitive to the previous history of large earthquakes in the region and indicate a need for detailed investigations to constrain the exact rupture geometries of previous earthquakes on these segments. © 2002 Elsevier Science B.V. All rights reserved.

DOI 10.1016/S0012-821X(01)00592-1
Citations Scopus - 74Web of Science - 68
2000 Marsan D, Bean CJ, Steacy S, McCloskey J, 'Observation of diffusion processes in earthquake populations and implications for the predictability of seismicity systems', Journal of Geophysical Research: Solid Earth, 105 28081-28094 (2000)

Scale invariance, either in space or in time, has been shown in many papers to characterize earthquake distributions. Unfortunately, little work has been dedicated to looking at t... [more]

Scale invariance, either in space or in time, has been shown in many papers to characterize earthquake distributions. Unfortunately, little work has been dedicated to looking at the general space-time scaling invariance of seismicity systems, even though a better understanding of how the two domains (spatial and temporal) link together could help the development of the stochastic dynamical modeling of earthquake populations. In this paper we report the observation of diffusion processes of temporally correlated seismic activity for three different data sets: a mine (Creighton Mine, Canada), the Long Valley Caldera in eastern California, and a 7-year period of recorded seismic activity in southern California. The observed subdiffusion processes are indicative of the general space-time scaling of the system, taking the form of a slow power law growth R(t) ~ tH of the mean distance R(t) between the main event and the temporally correlated afterevents occuring after a delay t. H is found on average to be small (0.1 for Creighton Mine, 0.22 for the Long Valley Caldera, and 0.22 for the southern California main events with magnitude = 1.5) but fluctuates significantly from one main event to the other: the diffusion is found to be intermittent (non-Gaussian) and multiscaling, and except for the Long Valley Caldera, a systematic correlation between the sizes of the main event and subsequent afterevents and the growth exponent H is observed. While classical viscous relaxation models (e.g., elastic listhosphere-plastic asthenosphere coupling, or fluid flow triggered by sudden changes in pore pressure) have been proposed to characterize this relaxation by homogeneous (i.e., nonintermittent) normal (H = 0.5) diffusion processes, the direct implication of the reported results is that seismicity systems, at spatial scales from meters to hundreds of kilometers and small (microearthquakes in a mine) to intermediate magnitudes, relax spatiotemporally in a nonelastic way, revealing the stochastic space-time scale-invariant nature of such systems. Since these diffusion processes correspond to a loss of information with time on the location of the main event, they can be used to investigate the limits of predictability, at all spatial scales, of seismicity systems in terms of the spatiotemporal clustering of temporally correlated earthquakes. Copyright 2000 by the American Geophysical Union.

DOI 10.1029/2000jb900232
Citations Scopus - 46Web of Science - 45
1999 Steacy SJ, McCloskey J, 'Heterogeneity and the earthquake magnitude-frequency distribution', GEOPHYSICAL RESEARCH LETTERS, 26 899-902 (1999)
DOI 10.1029/1999GL900135
Citations Scopus - 21Web of Science - 20
1999 Marsan D, Bean CJ, Steacy S, McCloskey J, 'Spatio-temporal analysis of stress diffusion in a mining-induced seismicity system', Geophysical Research Letters, 26 3697-3700 (1999)

The spatio-temporal correlation of micro-earthquakes occurring in a mining-induced seismic system (Creighton mine, Ontario, Canada) is investigated. It is shown that, when conside... [more]

The spatio-temporal correlation of micro-earthquakes occurring in a mining-induced seismic system (Creighton mine, Ontario, Canada) is investigated. It is shown that, when considering only the after-events correlated to a main event, i.e., not accounting for the uncorrelated regime of `background' activity, the spatial distribution of these after-events occurring at t after the main event change with t. This change takes the form of an expanding pattern, characterized by a typical scale Lc(t) varying as Lc(t) to approximately tH, H being estimated to 0.18. This diffusion exponent is found to increase when considering only a subset of the most energetic events as mainshocks. We interpret this result as the indication of a stress (sub-)diffusion mechanism, involving propagation on the heterogeneous fractal fault network.

DOI 10.1029/1999GL010829
Citations Scopus - 25Web of Science - 26
1998 Steacy SJ, McCloskey J, 'What controls an earthquake's size? Results from a heterogeneous cellular automaton', GEOPHYSICAL JOURNAL INTERNATIONAL, 133 F11-F14 (1998)
DOI 10.1046/j.1365-246X.1998.1331548.x
Citations Scopus - 27Web of Science - 27
1996 Steacy SJ, McCloskey J, Bean CJ, Ren JW, 'Heterogeneity in a self-organized critical earthquake model', GEOPHYSICAL RESEARCH LETTERS, 23 383-386 (1996)
DOI 10.1029/96GL00257
Citations Scopus - 22Web of Science - 24
1992 STEACY SJ, SAMMIS CG, 'A DAMAGE MECHANICS MODEL FOR FAULT ZONE FRICTION', JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH, 97 587-594 (1992)
DOI 10.1029/91JB02338
Citations Scopus - 12Web of Science - 11
1991 STEACY SJ, SAMMIS CG, 'AN AUTOMATON FOR FRACTAL PATTERNS OF FRAGMENTATION', NATURE, 353 250-252 (1991)
DOI 10.1038/353250a0
Citations Scopus - 102Web of Science - 93
Show 27 more journal articles

Conference (3 outputs)

Year Citation Altmetrics Link
2016 Welsh M, Steacy S, Begg S, Navarro DJ, 'A Tale of Two Disasters: Biases in Risk Communication.', CogSci (2016)
1997 Steacy SJ, McCloskey J, Bean CJ, Ren JW, 'Simulating seismicity in Creighton Mine: A 3-D self-organized critical model', ROCKBURSTS AND SEISMICITY IN MINES, KRAKOW, POLAND (1997)
Citations Web of Science - 1
1994 SAMMIS CG, STEACY SJ, 'THE MICROMECHANICS OF FRICTION IN A GRANULAR LAYER', PURE AND APPLIED GEOPHYSICS, SAN FRANCISCO, CA (1994)
DOI 10.1007/BF00876064
Citations Scopus - 46Web of Science - 46
Edit

Grants and Funding

Summary

Number of grants 18
Total funding $2,820,896

Click on a grant title below to expand the full details for that specific grant.


20171 grants / $345,000

Origins and Distributions of Intraplate Earthquakes$345,000

Funding body: ARC (Australian Research Council)

Funding body ARC (Australian Research Council)
Project Team

M.C. Quigley, S. Steacy, and L.N. Moresi

Scheme ARC Discovery
Role Investigator
Funding Start 2017
Funding Finish 2019
GNo
Type Of Funding C1200 - Aust Competitive - ARC
Category 1200
UON N

20112 grants / $296,576

Strategies and Tools for Real Time Earthquake Risk Reduction (REAKT)$231,941

Funding body: European Commission, European Union

Funding body European Commission, European Union
Scheme 7th Research Framework Programme
Role Investigator
Funding Start 2011
Funding Finish 2014
GNo
Type Of Funding C3231 - International Govt - Own Purpose
Category 3231
UON N

Research conference - Continuing Challenges In Earthquake Dynamics – New Methods For Observing and Modelling A Multi-Scale System$64,635

Funding body: European Science Foundation / Austrian Science Fund (FWF)

Funding body European Science Foundation / Austrian Science Fund (FWF)
Project Team

S. Steacy, D. Marsan, S. Hainzl, and A. Christophersen

Scheme European Science Conferences
Role Lead
Funding Start 2011
Funding Finish 2011
GNo
Type Of Funding C3231 - International Govt - Own Purpose
Category 3231
UON N

20101 grants / $70,157

Testing a hybrid Coulomb/statistical model of aftershock occurrence$70,157

Funding body: Natural Environment Research Council

Funding body Natural Environment Research Council
Project Team

S Steacy

Scheme Research grant
Role Lead
Funding Start 2010
Funding Finish 2012
GNo
Type Of Funding C3232 - International Govt - Other
Category 3232
UON N

20083 grants / $246,234

Research conference – New challenges in earthquake dynamics: Observing and modeling a multi-scale system$96,974

Funding body: European Science Foundation / Austrian Science Fund (FWF)

Funding body European Science Foundation / Austrian Science Fund (FWF)
Project Team

D. Marsan, S. Steacy, S. Hainzl, and A. Helmstetter

Scheme European Science Conferences
Role Investigator
Funding Start 2008
Funding Finish 2008
GNo
Type Of Funding C3231 - International Govt - Own Purpose
Category 3231
UON N

Evaluation of historical earthquake interaction and seismic risk to western Sumatra$89,652

Funding body: Natural Environment Research Council

Funding body Natural Environment Research Council
Project Team

J. McCloskey, S. Steacy, and S. S. Nalbant

Scheme Research grant
Role Investigator
Funding Start 2008
Funding Finish 2009
GNo
Type Of Funding C3231 - International Govt - Own Purpose
Category 3231
UON N

Research Fellowship – Rate-state friction and earthquake probabilities$59,608

Funding body: The Leverhulme Trust

Funding body The Leverhulme Trust
Project Team

S Steacy

Scheme Fellowship
Role Lead
Funding Start 2008
Funding Finish 2010
GNo
Type Of Funding C3220 - International Philanthropy
Category 3220
UON N

20073 grants / $682,369

Capability building for the enhanced geophysical interpretation of the dynamics of CO2 sequestration$563,580

Funding body: Griffiths Geoscience Awards

Funding body Griffiths Geoscience Awards
Project Team

J. McCloskey, S. Nalbant, S. Steacy, and R. Cassidy

Scheme Capability grant
Role Investigator
Funding Start 2007
Funding Finish 2013
GNo
Type Of Funding C3231 - International Govt - Own Purpose
Category 3231
UON N

Stress interaction, rate-state friction, and earthquake triggering$63,789

Funding body: Natural Environment Research Council

Funding body Natural Environment Research Council
Project Team

S. Steacy

Scheme Research grant
Role Lead
Funding Start 2007
Funding Finish 2009
GNo
Type Of Funding C3231 - International Govt - Own Purpose
Category 3231
UON N

Urgent assessment of the earthquake and tsunami hazard in western Sumatra following the 09/07 Mentawai Islands earthquake sequence$55,000

Funding body: Natural Environment Research Council

Funding body Natural Environment Research Council
Project Team

J. McCloskey, S. Steacy, and S. S. Nalbant

Scheme Research grant
Role Investigator
Funding Start 2007
Funding Finish 2008
GNo
Type Of Funding C3231 - International Govt - Own Purpose
Category 3231
UON N

20061 grants / $14,205

Assessing tsunami hazard in Sumatra: A Royal Society Summer Science exhibit$14,205

Funding body: Engineering and Physical Sciences Research Council

Funding body Engineering and Physical Sciences Research Council
Project Team

S. Steacy and J. McCloskey

Scheme Science outreach
Role Lead
Funding Start 2006
Funding Finish 2006
GNo
Type Of Funding C3231 - International Govt - Own Purpose
Category 3231
UON N

20053 grants / $244,530

Constrained heterogeneous loading of complex fault networks (CONSTRAIN)$170,848

Funding body: European Commission, European Union

Funding body European Commission, European Union
Project Team

S. Steacy and J. McCloskey

Scheme Marie Curie Actions - IRSES
Role Lead
Funding Start 2005
Funding Finish 2007
GNo
Type Of Funding C3231 - International Govt - Own Purpose
Category 3231
UON N

The influence of viscoelastic relaxation on the effective duration of Coulomb stress perturbations$51,232

Funding body: Natural Environment Research Council

Funding body Natural Environment Research Council
Project Team

S. S. Nalbant, J. McCloskey, and S. Steacy

Scheme Research grant
Role Investigator
Funding Start 2005
Funding Finish 2007
GNo
Type Of Funding C3231 - International Govt - Own Purpose
Category 3231
UON N

Tsunami Risk in the Indian Ocean from threatened M>8 event under Mentawai Islands$22,450

Funding body: Natural Environment Research Council

Funding body Natural Environment Research Council
Project Team

J. McCloskey, S. Steacy, and S. S. Nalbant

Scheme Research grant
Role Investigator
Funding Start 2005
Funding Finish 2006
GNo
Type Of Funding C3231 - International Govt - Own Purpose
Category 3231
UON N

20031 grants / $9,514

Urgent assessment of the location and orientation of the Bingöl rupture by mapping surface breaks$9,514

Funding body: Natural Environment Research Council

Funding body Natural Environment Research Council
Project Team

J. McCloskey, S. Steacy, and S.S. Nalbant

Scheme Research grant
Role Investigator
Funding Start 2003
Funding Finish 2003
GNo
Type Of Funding C3231 - International Govt - Own Purpose
Category 3231
UON N

20021 grants / $117,913

An investigation of the origin and nature of the Gutenberg-Richter relation$117,913

Funding body: Engineering and Physical Sciences Research Council

Funding body Engineering and Physical Sciences Research Council
Project Team

S. Steacy, J. McCloskey, and P. Morrow

Scheme Research Grant
Role Lead
Funding Start 2002
Funding Finish 2004
GNo
Type Of Funding C3231 - International Govt - Own Purpose
Category 3231
UON N

20001 grants / $776,783

Towards practical, real-time estimation of spatial aftershock probabilities: a feasibility study in earthquake hazard (PRESAP)$776,783

Funding body: European Commission, European Union

Funding body European Commission, European Union
Project Team

J. McCloskey and S. Steacy

Scheme Framework V
Role Investigator
Funding Start 2000
Funding Finish 2003
GNo
Type Of Funding C3231 - International Govt - Own Purpose
Category 3231
UON N

19991 grants / $17,615

An investigation of the relation between Coulomb stress perturbations, large aftershocks, and fault structure$17,615

Funding body: Natural Environment Research Council

Funding body Natural Environment Research Council
Project Team

S. Steacy

Scheme Research grant
Role Lead
Funding Start 1999
Funding Finish 2001
GNo
Type Of Funding C3231 - International Govt - Own Purpose
Category 3231
UON N
Edit

Professor Sandy Steacy

Position

Head of School
School of Environmental and Life Sciences
Faculty of Science

Contact Details

Email sandy.steacy@newcastle.edu.au
Phone (02) 4921 5084
Mobile 0488994606
Fax (02) 4921 5472

Office

Room C229
Edit