Stress interaction, rate-state friction, and earthquake triggering

Lead Research Organisation: University of Ulster
Department Name: Sch of Environmental Sciences


Over the past 10 years it has become very clear that stress changes due to large earthquakes can increase the likelihood of future large earthquakes. For example, the 26 December 2004 earthquake near Sumatra triggered the 28 March 2005 event near Nias Island and the increase in seismic risk in this area was noted in a paper published 11 days before the earthquake. Although such stress changes can be used to delineate areas of greater risk, it is very questionable as to whether we can say anything meaningful about the probability of earthquake occurrence in such regions. The problem is that the one model that relates stress and probability changes relies on a number of assumptions that may not be justified in reality. Testing the model with real earthquakes is difficult due to the small number of large events and issues with data quality in poorly instrumented areas. Hence, we propose to use a sophisticated seismic simulation model to systematically test whether earthquake probability changes can be related to stress changes.


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Steacy S (2014) A new hybrid Coulomb/statistical model for forecasting aftershock rates in Geophysical Journal International

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Steacy S (2014) Stress triggering and the Canterbury earthquake sequence in Geophysical Journal International

Description We found that there was a correlation between stress changes and the likelihood of triggered earthquakes but it wasn't straight-forward and the magnitude of the stress change did not directly correlate with the change in earthquake likelihood
Exploitation Route These results motivated our move to hybrid statistical / Coulomb models which have subsequently been shown to outperform Coulomb rate state forecasting models. The research on improving these models is continuing.
Sectors Environment

Description Operational earthquake forecasting 
Organisation GNS Science
Country New Zealand 
Sector Public 
PI Contribution Lead on stress interaction aspects of work
Collaborator Contribution Lead on statistical aspects of work
Impact The two GJI papers published in 2013, other papers in preparation, numerous conference presentations, my participation in an expert elicitation panel on Canterbury seismic hazard, my appointment as a visiting scientist at GNS
Start Year 2010