+ Site Statistics
+ Search Articles
+ PDF Full Text Service
How our service works
Request PDF Full Text
+ Follow Us
Follow on Facebook
Follow on Twitter
Follow on LinkedIn
+ Subscribe to Site Feeds
Most Shared
PDF Full Text
+ Translate
+ Recently Requested

Empirical Calibration of Local Magnitude Data Sets Versus Moment Magnitude in Italy



Empirical Calibration of Local Magnitude Data Sets Versus Moment Magnitude in Italy



Bulletin of the Seismological Society of America 103(4): 2227-2246



Using general orthogonal regressions (GORs), we calibrated local magnitudes, estimated in Italy using various methods in different periods of time from 1981 to 2010, with a set of homogeneous moment magnitudes (Mw). Magnitude uncertainties, necessary for the application of GOR methods, are inferred by a trial-and-error procedure based on a priori information and empirical regression results. We found that local magnitudes determined using real or synthesized Wood–Anderson waveforms (ML) scale 1:1 with Mw in most cases but in general underestimate Mw by about 0.1–0.2 magnitude units. The only significant deviation from the 1:1 scaling concerns the most recent data provided by the online ISIDE bulletin of the Istituto Nazionale di Geofisica e Vulcanologia and is probably due to the use of a distance correction table (–logA0) not fully appropriate for the Italian area. Magnitudes computed from the duration of the seismogram coda (MD) do not generally scale 1:1 with Mw and are also underestimated. The relevant regression coefficients vary significantly from one data set to another depending on the empirical formulas used by different catalogs and bulletins. The derived regression coefficients are used to build a homogenized catalog in terms of Mw that also includes a consistent estimate of uncertainty for all reported magnitudes. The analysis of the frequency–magnitude distribution of the resulting catalog, covering 30 years of data, shows a b-value slightly lower than 1, which is reasonably uniform over the different time intervals and data sets. It also shows a progressive decay of the earthquake rates below the best-fit straight line for Mw>4.5 that might reflect a magnitude distribution truncated or tapered to relatively small maximum magnitudes for some Italian seismic zones with low activity. This behavior also seems to exclude a characteristic earthquake recurrence mechanism for Italy.Online Material: Description of data sets and details of regression and frequency–magnitude distribution analyses.

Please choose payment method:






(PDF emailed within 0-6 h: $19.90)

Accession: 037245075

Download citation: RISBibTeXText

DOI: 10.1785/0120120356


Related references

Comparison of magnitude estimates for New Zealand earthquakes; moment magnitude, local magnitude, and teleseismic body-wave magnitude. Bulletin of the Seismological Society of America 99.3, 2009

Moment magnitude-local magnitude calibration for earthquakes off Canada's west coast. Bulletin of the Seismological Society of America 93(5): 2296-2300, 2003

Moment magnitude-local magnitude calibration for earthquakes in Western Canada. Bulletin of the Seismological Society of America 95(5): 1994-2000, 2005

Empirical relationship between moment magnitude and Nuttli magnitude for small-magnitude earthquakes in southeastern Canada. Seismological Research Letters 76(6): 752-755, 2005

Scaling relations of local magnitude versus moment magnitude for sequences of similar earthquakes in Switzerland. Bulletin of the Seismological Society of America 101.2, 2011

Impact of Magnitude Selection on Aleatory Variability Associated with GroundMotion Prediction Equations: Part ILocal, Energy, and Moment Magnitude Calibration and StressDrop Variability in Central Italy. Bulletin of the Seismological Society of America 108(3A): 1427-1442, 2018

Local and duration magnitudes in northwestern Italy, and seismic moment versus magnitude relationships. Bulletin of the Seismological Society of America 95(2): 592-604, 2005

A local earthquake coda magnitude and its relation to duration, moment M<O) , and local Richter magnitude M<L). Eos, Transactions, American Geophysical Union: 2, Pages 1193. 1977., 1977

Local magnitude, duration magnitude and seismic moment of Dahshour 1992 earthquakes. Annali di Geofisica 43(1): 95-103, 2000

Moment Magnitude MW and Local Magnitude ML Relationship for Earthquakes in Northeast India. Pure and Applied Geophysics 169(11): 1977-1988, 2012

Moment magnitude local magnitude relationship for the earthquakes of the Shillong-Mikir plateau, Northeastern India Region: a new perspective. Geomatics Natural Hazards and Risk 3(4): 365-375, 2012

Large contrast between the moment magnitude of tremor and the moment magnitude of slip in ETS events. Eos, Transactions, American Geophysical Union 90.52, Suppl, 2009

Absolute Magnitude Calibration for Red Giants Based on the Colour–Magnitude Diagrams of Galactic Clusters III Calibration with 2MASS. Publications of the Astronomical Society of Australia 30: e011, 2013

Absolute Magnitude Calibration for Giants Based on the Colour–Magnitude Diagrams of Galactic Clusters II Calibration with SDSS. Publications of the Astronomical Society of Australia 30: e008, 2013

Calibration of a local magnitude relationship for microseismic events using earthquake data. Geophysics 81(2): Ks215-Ks224, 2016