Quantifying the probability and uncertainty of multiple-structure rupture for Taiwan

This study identifies structure pairs with the potential for simultaneous rupture in a coseismic period and quantifies their rupture recurrence intervals. To assess the potential for a multiple-structure rupture, we calculated the probability of Coulomb stress triggering between seismogenic structures in Taiwan. We assumed that a multiple-structure rupture would occur if two structures could trigger each other by enhancing the plane with thresholds of a Coulomb stress increase and the distance between the structures and identified various sets of seismogenic structure pairs accordingly. We discussed the uncertainty of multiple-structure pair identification from various thresholds of stress change and structure distances, effective friction coefficient, and rotation of rake angles. To estimate the recurrence intervals for multiple-structure ruptures, we implemented a scaling law and the Gutenberg-Richter law in which the slip rate could be partitioned based on the magnitudes of the individual structure and multiple-structure ruptures. Considering that one structure may be involved in multiple cases of multiple-structure ruptures, we developed new formulas for slip partitioning in a complex fault system. By implementing the range of rupture area and slip rate of each structure, the magnitudes and recurrence intervals of multiple-structure ruptures could be estimated. We discussed the epistemic uncertainties of recurrence interval from deviations of slip rate and rupture area, various empirical formula of rupture parameters. The multiple-structure rupture with a larger characteristic magnitude would be crucial for the safety evaluation of infrastructures.