| Abstrakt: |
We investigate the relationship between the seismogenic behavior of global megathrusts and various subduction parameters. We performed a parametric approach by implementing three decision tree‐based Machine Learning (ML) algorithms to predict the b‐value of the frequency‐magnitude relationship of seismicity as a non‐linear combination of subduction variables (subducting plate age and roughness, slab dip, convergence speed and azimuth, distance to closest ridge and plate boundary). Using the Shapley Additive exPlanations (SHAP) to interpret the ML results, we observe that plate age and subduction dip are the most influential variables. The results suggest that older, shallow‐dipping plates contribute to low b‐values, indicating higher megathrust stress. This pattern is attributed to the higher rigidity of older plates, increasing flexural strength, and generating a shallow penetration angle, increasing the frictional interplate area and intensifying the megathrust stress. These findings offer new insights into the non‐linear complexity of seismic behavior at global scale. Plain Language Summary: We carried out a study to investigate how certain characteristics of subduction zones, where one tectonic plate slides under another, influence the earthquakes behavior. Using different machine learning algorithms we examined how different variables in these zones affect the relative amount of small versus large earthquakes, parameterized by the slope of a log‐normal relationship between frequency and magnitude of events, known as the b–value. Our analysis showed that the age of the subducting plate and the angle at which it dips under another plate are the most influential factors in earthquake behavior. In particular, we found that older plates with shallow subduction angles are associated with higher stress at the subduction interface, which in turn, increases the probability of large earthquakes, decreasing the b‐value. This is because older, colder plates are more rigid than young and hot plates, which increases their resistance to bending, augmenting the contact area between the plates and the friction between them. These findings shed light on the complex dynamics of seismic activity on a global scale and provide valuable information for understanding the earthquake behavior worldwide. Key Points: The non‐linear relationship between subduction parameters and seismogenic behavior, as represented by the b‐value, is exhibitedPlate age and subduction angle are shown as the most impactful parameters in megathrust stress worldwideOlder subducting plates with lower subduction angles are associated with lower b‐values, implying higher megathrust stress, and viceversa [ABSTRACT FROM AUTHOR] |
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