ALBERT

Description: 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. 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. We discussed the uncertainties of multiple-structure rupture pair identification from various thresholds of stress change and structure distances, effective friction coefficient, and rotation of rake angles. Note that since our approach is based on static Coulomb stress change, the possibility of a multiple-structure rupture in a coseismic period might be overestimated. To estimate the recurrence intervals for multiple-structure ruptures, we implemented a scaling law and the Gutenberg-Richter law. Considering that a single structure may be involved in multiple cases of multiple-structure ruptures, we developed new formulas for slip partitioning in a complex fault system. We discussed the uncertainty of recurrence interval from epistemic uncertainties from deviations of slip rate and rupture area, various empirical formula of rupture parameters. Due to a larger characteristic magnitude and a larger displacement of the multiple-structure rupture, the rupture’s recurrence interval could be longer. Therefore, considering the multiple-structure rupture leads to an increase in seismic hazard in a long return period, crucial for the safety evaluation of infrastructures.

Description: The aim of the study is to analyze the existing ground motion prediction equations (GMPEs) applicable in Albania for horizontal peak ground acceleration (PGA) and spectral acceleration (SA). We present four sets of GMPEs evaluated for Albania using a dataset of instrumental strong-motion records from the November 26, 2019, Mw6.4 Durres earthquake. Besides the mainshock, the models are tested for foreshock and aftershock events of magnitude Mw〉5.0. The GMPEs from Boore et al., (2014), Chiou and Youngs (2014), and Kotha et. al., (2020), provide a better fit to the ground-motion attenuation observed for the mainshock at distances up to 400 km, while Akkar et. al., (2014) fit better at a short distance. Along with the seismological aspects of the earthquake, we give an overview of the damages and social consequences, considering the engineering seismology source of data known as “Did You Feel It?” (DYFI) and the 1360 DYFI online citizen responses collected after the Durres event. The DYFI data are higher than instrumentation data, better represented using SA at 0.3s. By integrating the instrumentally observed data with the macroseismic observed data, we explore the importance of human response to the concept of ground shaking, demonstrating how this type of information can indeed reduce the gap in regions with a limited number of near-field stations. Therefore, this study makes a major contribution to the selection of GMPEs and provides a useful reference for the logic tree structure in subsequent seismic hazard assessment on both national and regional scales.