Magnitudes are an essential parameter for the estimation of source properties and the management of seismic risk, yet they are surprisingly difficult to accurately estimate. In this paper we show the challenges of working with microseismic events, and propose approaches to correct for some of the discrepancies that are commonly observed. Local magnitudes are regularly over-estimated at close hypocentral distances, and we present revised scales to correct for these discrepancy. As the magnitude decreases the frequency content of the source spectra would be expected to increase. This is however demonstrated not to be the case for microseismic events, which has an impact on the calculation of source properties and relationships between Local and Moment magnitude. We overcome this be adapting standard Brune source model to account for a preferential decay of high frequencies. This is used to derive a physics-based ML-MW relationship, and estimate the rupture radius and stress drop of a cluster of seismic events.


Article metrics loading...

Loading full text...

Full text loading...


  1. Bishop, I., Styles, P. & Allen, M.
    , 1993. Mining-induced seismicity in the Nottinghamshire Coalfield. Quarterly Journal of Engineering Geology and Hydrogeology, 26(4), pp.253–279.
    [Google Scholar]
  2. Brune, J.N.
    , 1970. Tectonic stress and the spectra of seismic shear waves from earthquakes. Journal of Geophysical Research, 75(26), pp.4997–5009.
    [Google Scholar]
  3. Butcher, A. et al.
    , 2017. Local Magnitude Discrepancies for Near-Event Receivers: Implications for the U.K. Traffic-Light Scheme. Bulletin of the Seismological Society of America, 107(2), pp.532–541.
    [Google Scholar]
  4. Deichmann, N.
    , 2017. Theoretical Basis for the Observed Break in Ml/ Mw Scaling between Small and Large Earthquakes. Bulletin of the Seismological Society of America, 107(2), pp.505–520.
    [Google Scholar]
  5. Dost, B., Edwards, B. & Bommer, J.J.
    , 2018. The Relationship between M and ML: A Review and Application to Induced Seismicity in the Groningen Gas Field, The Netherlands. Seismological Research Letters
    [Google Scholar]
  6. Hanks, T.C. & Kanamori, H.
    , 1979. A moment magnitude scale. Journal of Geophysical Research, 84(B5), pp.2348–2350.
    [Google Scholar]
  7. Hutton, L.K. & Boore, D.M.
    , 1987. The Ml Scale in Southern California. Bulletin Of The Seismological Society Of America, 77(6), pp.2074–2094.
    [Google Scholar]
  8. Stork, A.L. & Ito, H.
    , 2004. Source parameter scaling for small earthquakes observed at the western Nagano 800-m-deep borehole, Central Japan. Bulletin of the Seismological Society of America, 94(5), pp.1781–1794.
    [Google Scholar]
  9. Verdon, J.P. et al.
    , 2018. Seismicity induced by longwall coal mining at the Thoresby Colliery, Nottinghamshire, U.K.Geophysical Journal International, 212(2), pp.942–954.
    [Google Scholar]

Data & Media loading...

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error