A High-frequency Magnitude Scale (M3HZ): From Instrumental Ground Motions to Historical Earthquake Catalogs
Description:
An accurate characterization of earthquake size is essential for seismology and earthquake engineering, particularly in seismic hazard and risk assessments. Widely used magnitude scales such as Ms and Mw provide robust estimates of overall source size but are not designed to capture variability in high-frequency radiation, which largely controls damaging ground shaking. Conversely, local magnitude (ML) better reflects high-frequency seismic-wave energy but saturates for large earthquakes, limiting its applicability.
Building on the concept of high-frequency magnitude introduced by Atkinson and Hanks (1995), we propose here a novel magnitude scale, m3Hz, which is specifically designed to quantify high-frequency radiation above the source corner frequency. The scale incorporates corrections for crustal structure and site effects. First, we present how m3Hz is computed and applied to instrumentally recorded ground-motion data. Then, we demonstrate its ability to capture high-frequency source effects through comparisons with independent source parameters using datasets from Central Italy and Japan. Finally, we extend the approach to macroseismic intensity data, and illustrate its application to historical earthquakes in Italy. Using macroseismic intensity data from the Italian Macroseismic DataBase Earthquakes (DBMI15), we estimate m3Hz for 1,951 events spanning the period 1117–2020, producing a new high-frequency earthquake catalogue, named ICEM. For each event, we assign a quality index based on the variance-to-mean ratio (VMR) to quantify the robustness of the estimates.
The ICEM catalogue shows how m3Hz complements Mw by providing information on earthquake source complexity and high-frequency radiation relevant to damage potential. It offers a new approach to integrating source properties into seismic hazard and risk assessments.
Session: Advancing Seismic Hazard and Risk Assessment through Multi-Disciplinary Approaches [Poster]
Type: Poster
Date: 4/15/2026
Presentation Time: 08:00 AM (local time)
Presenting Author: Stefano Parolai
Student Presenter: No
Invited Presentation:
Poster Number: 36
Authors
Stefano Parolai Presenting Author Corresponding Author stefano.parolai@units.it University of Trieste |
Daniele Spallarossa daniele.spallarossa@unige.it University of Genova |
Matteo Picozzi mpicozzi@ogs.it National Institute of Oceanography and Applied Geophysics |
Rouhollah Amiri Fard Rouhollah.amirifard@phd.units.it University of Trieste |
Adrien Oth adrien.oth@ecgs.lu European Center for Geodynamics and Seismology |
Dino Bindi dino.bindi@gfz.de GFZ Postdam |
Andrea Rovida andrea.rovida@ingv.it National Institute of Geophysics and Volcanology |
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A High-frequency Magnitude Scale (M3HZ): From Instrumental Ground Motions to Historical Earthquake Catalogs
Category
Advancing Seismic Hazard and Risk Assessment through Multi-Disciplinary Approaches