A High‐Resolution Seismic Catalog for the Southern Apennines (Italy) Built Through Template‐Matching

Abstract

The incompleteness of earthquake catalogs is a well-known issue caused by our technical limitation in detecting the small-to very small-magnitude seismicity falling near or below the background seismic noise. The detection of small-magnitude events is fundamental for improving our knowledge of geometry and kinematics of seismogenic sources and the spatio-temporal characteristics of seismicity, thus leading to better models for seismic hazard. Template-matching (TM) is a powerful technique that, based on similarity measure (cross-correlation) of seismic waveforms, allows to detect hidden earthquakes that are similar to known events (called templates). The high computational effort often limits such technique to small areas and for short time frames (less than 1 year). In this work, we present the first application of template-matching at regional scale for the Italian Peninsula, focusing on the Southern Apennines. We use about 3,600 high-quality events as templates, scanning 6-year long continuous recordings (2009–2014), at more than 180 stations of the INGV network. About 20,000 new events are found, showing a comparable quality to the template catalog in terms of hypocentral solution, reaching a decrease of the magnitude of completeness of about one unit. To highlight the improved quality of the TM catalog, we report two main examples regarding the Sannio-Matese area, where TM allowed us to unravel relevant details on the spatio-temporal distribution of the local seismicity.