Recipient organisationCardiff UniversitySource-published name: Cardiff University
Funding£2.0M
PeriodApr 2024 — Apr 2029
In plain English
AI plain-English summary
Tectonic faults can either rupture in destructive earthquakes or creep silently, and scientists do not fully understand why one fault slips one way while another slips another. This matters because current earthquake forecasting models rely on lab experiments with single rock types, which cannot capture how real faults behave over kilometres and multiple earthquake cycles. The ASPERITY project will collect geological evidence from ancient fault zones preserved in rocks, link those observations to lab experiments, and build computer models that span from microscopic deformation to entire plate boundaries. The central hypothesis is that the interaction between earthquake-generating patches—called asperities—and the surrounding fault rock determines whether a fault slips violently or creeps. If successful, the research could transform earthquake forecasting from empirical guesswork into physics-based predictions. Engineers and planners could better assess which fault segments pose the greatest seismic hazard, informing building codes and infrastructure resilience in earthquake-prone regions. The work is fundamental science, but understanding why some faults creep harmlessly while others rupture catastrophically has direct implications for public safety and infrastructure protection.
View original technical description
Where and why tectonic faults produce earthquakes or slip aseismically is a critical Earth Science question that remains unanswered, despite representing prerequisite knowledge for probabilistic earthquake forecasting. It is known that earthquakes are typically generated by frictional failure, which initiates where stress is high or strength is low relative to bulk fault zone strength. Fault zones therefore have earthquake-generating patches ('asperities') surrounded by areas likely to creep aseismically. This varied behaviour has been ascribed to variation in fault zone properties. Current models for the spectrum of fault slip styles, however, are based on laboratory-scale observations, typically in single rock types, described by sophisticated empirical constitutive laws. These laws lack insights into underlying physical properties and interaction of multiple materials over km-scales and multiple earthquake cycles. This is a critical knowledge gap that prevents development of realistic earthquake models - ASPERITY will bridge this gap. ASPERITY proposes a generalised model for natural faults where 'asperities' are defined as areas where, over an earthquake cycle, the amount of co-seismic slip exceeds the magnitude of aseismic creep. This model raises the specific hypothesis that interaction between asperities and surrounding fault rock determines fault slip style. To test this hypothesis, we will collect quantitative geological evidence from the rock record, link natural and laboratory deformation microstructures, and develop numerical models to bridge the scale to plate boundary faults. This will lead to specific scenarios that forecast where earthquakes, creep, and slow earthquakes occur in terms of variables that can be quantified in nature. This outcome is a step-change from empirical to physical understanding of where and why some tectonic faults move in episodic, potentially damaging earthquakes, while others creep silently and pseudo-continuously.
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