A Proposal for a High-Frequency Earthquake Magnitude (m3Hz) for Seismic Hazard and Rapid Damage Assessment

Abstract Obtaining a size estimate of an earthquake that well represents its potential impact is of primary importance in seismology and earthquake engineering. The magnitude scales currently used in earthquake catalogs, mainly Ms and Mw, are not designed to represent the variability of shaking due to variations in high-frequency radiation. Conversely, ML, which best describes the seismic-wave energy released by an earthquake, is unable to provide an accurate representation of events with magnitudes exceeding approximately 6.5. Therefore, building on and extending the concept of high-frequency magnitude (Atkinson and Hanks, 1995), we propose in this article a new high-frequency magnitude scale m3Hz. This magnitude is estimated by also considering correction factors for the crustal model and site effects. We apply the new magnitude scale m3Hz to two data sets (Central Italy and Japan) and validate its ability to capture high-frequency radiation effects through comparison with available source parameters. Finally, a procedure for estimating m3Hz is also proposed for preinstrumental earthquakes. This procedure addresses a limitation of previous magnitude estimation techniques, such as Me, and is validated for four events for which both macroseismic and instrumental intensity data are available.