Effects of failure parametrization on pre- and coseismic earthquake rupture

SUMMARY This study investigates the impact of different slip-dependent fault failure parametrizations on the pre-seismic and coseismic phases of the earthquake cycle using 2-D finite element simulations. Various failure laws are considered: linear slip-weakening, double slip-weakening, parabolic cohesive zone and exponential cohesive zone laws. The pre-seismic phase is modelled using a quasi-static approach, while the coseismic phase is modelled dynamically. Results demonstrate the importance of accounting for the different shapes of failure laws during the pre-seismic phase, as they lead to variations in pre-seismic phase duration, associated pre-seismic slip and lateral extent of slip front. Failure laws with gentler initial slopes require more time to initiate dynamic rupture compared to those with steeper initial weakening slopes. The presence of an initial strengthening segment in the failure law affects the amount and lateral extent of pre-seismic slip. During dynamic rupture propagation, the specific details of the failure law become less significant due to the Lorentz contraction of the process zone. However, variations in the duration of the pre-seismic phases result in different dynamic stress drops and, consequently, variations in rupture acceleration times and earthquake magnitudes for different failure laws.