On the Relationship between ML and Mw in a Broad Range: An Example from the Apennines, Italy

Brief Report| January 16, 2018 On the Relationship between ML and Mw in a Broad Range: An Example from the Apennines, Italy Luca Malagnini; Luca Malagnini aIstituto Nazionale di Geofisica e Vulcanologia, via di Vigna Murata 605, 00143 Rome, Italy, luca.malagnini@ingv.it, irene.munafo@ingv.it Search for other works by this author on: GSW Google Scholar Irene Munafò Irene Munafò aIstituto Nazionale di Geofisica e Vulcanologia, via di Vigna Murata 605, 00143 Rome, Italy, luca.malagnini@ingv.it, irene.munafo@ingv.it Search for other works by this author on: GSW Google Scholar Author and Article Information Luca Malagnini aIstituto Nazionale di Geofisica e Vulcanologia, via di Vigna Murata 605, 00143 Rome, Italy, luca.malagnini@ingv.it, irene.munafo@ingv.it Irene Munafò aIstituto Nazionale di Geofisica e Vulcanologia, via di Vigna Murata 605, 00143 Rome, Italy, luca.malagnini@ingv.it, irene.munafo@ingv.it Publisher: Seismological Society of America First Online: 16 Jan 2018 Online Issn: 1943-3573 Print Issn: 0037-1106 © Seismological Society of America Bulletin of the Seismological Society of America (2018) 108 (2): 1018–1024. https://doi.org/10.1785/0120170303 Article history First Online: 16 Jan 2018 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Luca Malagnini, Irene Munafò; On the Relationship between ML and Mw in a Broad Range: An Example from the Apennines, Italy. Bulletin of the Seismological Society of America 2018;; 108 (2): 1018–1024. doi: https://doi.org/10.1785/0120170303 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyBulletin of the Seismological Society of America Search Advanced Search Abstract Being tied to a physical quantity, moment magnitude (⁠Mw⁠) should be the reference estimate of earthquake size and used whenever possible. Local magnitude (⁠ML⁠) represents a simple alternative for a reliable estimate of size, its best use being either for quick outcomes or when the computation of Mw is difficult (e.g., for small earthquakes). However, ML and Mw are profoundly different and not interchangeable.Here, we analyze a large set of 1509 ML–Mw data points from earthquakes of the central and northern Apennines (CNA), quantify the empirical scaling, and look for features of global validity. Our data set is made of 449 unpublished Mws from moment tensor solutions of events from the Amatrice‐Visso‐Norcia (AVN) sequence, 170 published Mws from moment tensor solutions of events from the L'Aquila seismic sequence (2009), and 890 published ML–Mw data points from earthquakes of the Altotiberina fault (ATF, 2010–2014; Mws from spectral correction). We integrate our empirical data set by computing the local magnitudes of the events from the AVN and L'Aquila sequences.Our analysis of CNA earthquakes shows that, for earthquakes up to a crossover magnitude MLCO≈4.3⁠: Mw=23ML+C′;C′=1.14.Moreover, for earthquakes with ML>MLCO⁠, up to ML 6.5, our data suggest Mw=bML+C′′;b=1.28;C′′=−1.50,in which b depends on the combined effects of source scaling and crustal attenuation, and C′ and C″ on regional attenuation (⁠G(r)⁠, Q(f )⁠, κ0⁠), focal depth, and rigidity at source.Finally, a synthetic study calibrated on the crustal attenuation and the source characteristics of the AVN data set reproduces the observed scaling between ML and Mw⁠, predicting that MLs in the analyzed region saturate above ML∼6.5⁠. Smooth transitions are predicted between the different regimes. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.