Control of asperities size and spacing on seismic behavior of subduction megathrusts. Issue 16 (19th August 2017) - Corbi, Fabio
Abstract: The majority of the largest subduction megathrust earthquakes share the common characteristic of rupturing more than one asperity along strike of the margin. Understanding the factors that control coseismic failure of multiple asperities, and thus maximum magnitude, is central for seismic hazard assessment. To investigate the role of asperities size and spacing on maximum magnitude, seismicity rate, and percentage of synchronized ruptures, we use analog models simulating along‐strike rupture behavior of megathrust earthquakes. We found negative correlations between the barrier‐to‐asperity length ratio Db/Da and maximum magnitude and seismicity rate. Db/Da also controls the process of asperities synchronization along the megathrust. A permanent barrier behavior is observed for Db/Da > 0.5. Comparing our experimental results to the Nankai Trough historical seismicity, we propose that the distribution of megathrust frictional heterogeneities likely explains the diversity of earthquakes which occurred there. Key Points: We use analog models simulating along‐strike rupture behavior of megathrust earthquakes, including asperities synchronization The barrier‐to‐asperity length ratio negatively correlates with maximum magnitude and seismicity rate The barrier‐to‐asperity length ratio controls the process of asperities synchronization and in turn the maximum earthquake magnitude