NESS2.0: An Updated Version of the Worldwide Dataset for Calibrating and Adjusting Ground-Motion Models in Near Source

Abstract

We present an extended and updated version of the worldwide NEar‐Source Strong‐motion (NESS) flat file, which includes an increased number of moderate‐to‐strong earthquakes recorded in epicentral area, new source metadata and intensity measures, comprising spectral displacements and fling‐step amplitudes retrieved from the extended baseline correction processing of velocity time series. The resulting dataset consists of 81 events with moment magnitude≥5.5 and hypocentral depth shallower than 40 km, corresponding to 1189 three‐component waveforms, which are selected to have a maximum source‐to‐site distance within one fault length. Details on the flat files, metadata, and ground‐motion parameters, processing scheme, and statistical findings are presented and discussed. The analysis of these data allows recognizing the presence of distinctive features (such as pulse‐like waveforms, large vertical components, and hanging‐wall effects) that can be exploited to assess their impact on near‐source seismic motion. As an example, we use the NESS2.0 dataset for calibrating an empirical correction factor of a regional ground‐motion model (GMM) mainly based on far‐field records. In this way, we can adjust the median predictions to account for near‐source effects not fully captured by the reference model. The final goal of this work is to promote the use of the NESS2 flat file as a tool to disseminate qualified and referenced near‐source data and metadata in the light of improving the constraints of GMMs (both empirical and physics‐based) close to the source.