Review of methods for characterization of active faults for seismic hazard purposes.

This work presents a review of some methods for seismic hazard assessments based on hybrid source models, composed of active faults and seismic zones. These approaches are applied in a slow deformation area, defined as areas where the slip rate of the active faults is slower than 5 mm/yr.

The introduction of active faults as independent seismic sources in seismic hazard assessment has a great impact on the results that can be obtained in urban areas close to active faults, with respect with those obtained with classical zoning methods (CZM). 

Currently, there are no widely contrasted methodological developments to include zones and the characterized active faults in the source models, especially in slow deforming areas. Even though, some approaches that have used hybrid models (HM) composed of zone-type sources and fault-type sources, revealed that expected ground motion values around main faults may double (on average) those obtained by zoned models, in agreement with observations in recent earthquakes (Rivas-Medina, A., 2018; Gómez-Novell O., 2020).

This presentation compares some methods that address two key aspects: how to quantify the geological information and transfer it to recurrence models, and how to distribute the seismic potential between the two types of sources. Some of these methods are: 1) Moment-rate based method proposed by Bungum (2007), 2) Slip-rate based method also proposed by Bungum (2007), 3) Hybrid method developed by Rivas-Medina et al. (2019).

This study is centered in the Eastern Betics Shear Zone (EBSZ) in southeast Spain, which is a low to moderate seismicity region. These methods were applied in the seismic zones 37 and 55 defined by Garcia-Mayordomo (2015) due to the seismological and geological data availability of the present faults in each zone.