Construction of a ground motion flatfile for subduction earthquakes in the Mediterranean area

This work summarizes the procedure for constructing a dataset of accelerometric and velocimetric recordings of earthquakes in the subduction zones of the Mediterranean Basin. The aim is to improve the ground motion characterization of this type of events by calibrating a brand-new predictive model (GMMs) for the next generation of seismic hazard models in Europe. 

The database consists of three components ground-motion recordings from selected earthquakes in subduction zones, collected and processed uniformly through the ESM (Engineering Strong Motion database, https://esm-db.eu/#/home; (Luzi, et al., 2020)) infrastructure. The dataset also includes several supporting data (metadata) relative to source (magnitude estimates and focal mechanisms), path (different distance metrics), and site (VS,30 and soil classification according to the Eurocode 8). The earthquakes are located in the Calabrian Arc, Cyprus Arc, and Hellenic Arc, whose geometries are defined based on studies carried out in the framework of the European Fault-Source Model 2020 (Basili, et al., 2022). The preliminary dataset consists of 9910 records of 475 events with a magnitude range between 2.9 to 6.6. The events that occurred in the subduction zones are classified into interface and intra-slab events, according to different strategies, since their position relative to the slab can induce different near-source. A flag to identify stations in backarc or fore-arc position is also introduced since different rates, propagation characteristics, and characteristics of ground motion attenuation characterize them. The ground motion parameters will also be compared with available datasets for other worldwide subduction zones, such as the NGA-Sub database (Mazzoni, et al., 2021). The dataset will be finally disseminated through a flatfile (parametric table), formatted according to the ESM flatfile specification (Lanzano, et al., 2019).