Two-dimensional empirical rupture simulation: case study and applications to seismic hazard
Ethan Walsh1, Tim Stahl1, Andrew Howell1,2, Tom Robinson1
1 - School of Earth and Environment, University of Canterbury, Christchurch, New Zealand
2 - GNS Science, Avalon, Lower Hutt, New Zealand
Project Number: 3157
Abstract
Databases of historical surface rupturing earthquakes provide empirical constraints on the variables that influence multi-segment and multi-fault earthquakes. Here, we develop a numerical simulation that uses passing probabilities derived from surface rupture databases to characterize different rupture pathways initiating on a seed fault. The empirical rupture simulator (ERS) uses step distance, number of steps, angular change, and kinematic change to compute a combined passing probability for all fault section connections within 10 km of the seed fault and subsequent active ends of the propagating rupture. Ruptures end when all possible active ends fail to pass to the next section and the next iteration begins. We applied the ERS to two seed faults in the region of the 2016 Kaikoura (New Zealand) earthquake and compared the results to independent constraints on paleoseismic magnitude, segmentation, and global estimates of rupture complexity. Rupture set characteristics change dramatically based on seed fault location and indicate that kilometer-scale structural discontinuities serve as persistent barriers to rupture. Length-based magnitudes generally agree with those estimated from paleoseismic single event displacements. Our preferred model reproduces total trace complexity of historical earthquake catalogues and rarely generates ‘Kaikoura-earthquake-type’ events. Where appropriate, this semi-empirical approach may be useful for filtering or weighting on-fault maximum magnitudes in earthquake rupture forecasts. Alternatively, it could be used a straightforward tool for estimating maximum likely magnitudes. Further developments incorporating slip rate-based seeding might allow results to be compared to other established method of rupture simulation.
Published article:
Walsh, E., T. Stahl, A. Howell, and T. Robinson (2022). TwoDimensional Empirical Rupture Simulation: Examples and Applications to Seismic Hazard for the Kaikōura Region, New Zealand, Seismol. Res. Lett. XX, 1–19,
doi: 10.1785/0220220231(external link).