Calibration of IASPEI Standard Broad-band Magnitude mB for Iranian Plateau Earthquakes

Document Type : Research Article


1 Department of Seismology, Institute of Geophysics, University of Tehran, Tehran, Iran. E-mail:

2 Corresponding Author, Department of Seismology, Institute of Geophysics, University of Tehran, Tehran, Iran. E-mail:


Located in Alp-Himalayan belt and an active tectonic plate, Iran is annually struck by major earthquakes. Since shallow earthquakes cause considerable loss of lives and property in this region, using any method to decrease the time of magnitude estimation of great earthquakes is very important for making a prompt decision about what to do. To achieve this aim, mB was computed as a rapid estimator for 38 earthquakes with magnitudes greater than 6 occurred in Iran and adjacent areas (24°-44°N, 42°-66°E) from 1990 to 2018. The magnitudes that estimated by using the calibration function by Saul & Bormann (2007) have a standard error of 0.49 from Mw (in this study). Therefore, mB’s calibration function was modified. As a result, the magnitudes obtained are approximately equal to those of reported Mw (a standard error of 0.18). The calibration function acquired in this study for Iran’s earthquakes is lower than the mB’s global calibration function obtained by Saul & Bormann (2007). Their difference is nearly one unit at short distances, which can be related to the earthquakes located in subduction zones and plates boundaries used by Saul & Bormann (2007) that systemically have lower stress drops than intraplate earthquakes considered here. Thus it is needed to develop improved region-specific calibration functions for mB. However, the difference became smaller at distances greater than 20°. Consequently, this method and new calibration function can be employed to estimate magnitudes as early as possible across Iran plateau.


Main Subjects

Allmann, B.P., & Shearer, P.M. (2009). Global variations of stress drop for moderate to large earthquakes. Journal of Geophysical Research, 114(B01), 310.
Astiz, L., Earle, P., & Shearer, P. (1996). Global stacking of broadband seismograms. Seismological Research Letters, 67 (4), 8–18. doi:
Berberian, M., & Walker, R. (2010). The Rüdbar Mw 7.3 earthquake of 1990 June 20; seismotectonic, coseismic and geomorphic displacements, and historic earthquakes of the western high-Alborz,
Iran. Geophysical Journal International, 182(3), 1577–1602, DOI:10.1111/j.1365-246X.2010.04705.x, URL:
Boatwright, J., & Choy, G.L. (1986). Teleseismic estimates of the energy radiated by shallow earthquakes. Journal of Geophysical Research: Solid Earth, 91(B2), 2095–2112, DOI 10.1029/JB091iB02p02095, URL
Bormann, P., & Dewey, J. W. (2014). The new IASPEI standards for determining magnitudes from digital data and their relation to classical magnitudes. In: Bormann, P. (Ed.), New Manual of Seismological Observatory Practice 2 (NMSOP-2), Potsdam: Deutsches GeoForschungsZentrum GFZ, 1-44.
Bormann, P., & Khalturin, VI. (1975). Relations between different kinds of magnitude determinations and their regional proceedings of the xivth general assembly of the European seismological commission, trieste, sept. 16-22, 1974, ed. H. Stiller, 27-39, Berlin. National komitee for Geodesie und Geophysik bei der Akademie der Wissenschaften der DDR.
Bormann, P., & Saul, J. (2008). The new IASPEI standard broadband magnitude mB. Seismological Research Letters, 79(5), 698–705.
Bormann, P., & Saul, J. (2009). A fast, non-saturating magnitude estimator for great earthquakes. Seismological Research Letters, 80(5), 808–816.
Bormann P., & Wylegalla, K. (2005). Quick estimator of the size of great earthquakes. Eos, Transactions, American Geophysical Union, 86(46), 464.
Bormann, P., Wylegalla, K., & Saul, J. (2006). Near real-time broadband body-wave magnitudes mB and mBc: Automatic procedure for reliable magnitude estimates of strong earthquakes. In: USGS Tsunami Sources Workshop at, Menlo Park,
Bormann, P., Liu, R., Ren, X., Gutdeutsch, R., Kaiser, D., & Castellaro, S. (2007). Chinese national network magnitudes, their relation to NEIC magnitudes, and recommendations for new IASPEI magnitude standards. Bulletin of the Seismological Society of America, 97(1), 114-127.
Chung, D.H., & Bernreuter, D.L. (1980). Regional relationships among earthquake magnitude scales. US Nuclear Regulatory Commission Lawrence Livermore Laboratory: Washington, D. C. 20, 555.
Duputel, Z., Kanamori, H., Tsai, C., Rivera, L., Meng, L., Ampuero, J., & Stock, J., (2012). The 2012 Sumatra great earthquake sequence. Earth and Planetary Science Letters, (351–352), 247-257.
Duputel, Z., & Hayes, G. (2012). W-phase fast source inversion for moderate to large earthquakes (1990 - 2010). Geophysical Journal International, 189(2), 1125–1147.
Dziewonski, A.M., Chou, T.A., & Woodhouse, J.H. (1981). Determination of earthquake source parameters from waveform data for studies of global and regional seismicity. J. Geophysics Res., 86, 2825–2852, DOI 10.1029/JB086iB04p02825.
Ekström, G., Nettles, M., & Dziewonski, A.M. (2012). The global CMT project 2004-2010: Centroid-moment tensors for 13,017 earthquakes. Phys. Earth Planet Inter., 200-201, 1–9, DOI 10.1016/j.pepi.2012.04.002.
Engelder, T. (2014). Stress Regimes in the Lithosphere. Princeton University Press, URL
Evernden, J.F. (1967). Magnitude determination at regional and near regional distances in the United States. Bull. Seism. Soc. Am., 57(4):591-639.
Gutenberg, B., & Richter, C. F. (1956). Magnitude and Energy of Earthquakes. Annals of Geophysics, 9(1), 1-15. doi:10.4401/ag-5590.
Gutenberg, B. (1945). Magnitude determination for deep-focus earthquakes. Bulletin of the Seismological Society of America, 35(3), 117–130. doi:
Hanks, T.C., & Kanamori, H. (1979). A moment magnitude scale. J. Geophysics Res., 84(B5), 2348–2350.
Hayes, G., Rivera, L., & Kanamori, H. (2009). Source Inversion of the W-Phase: Real-time Implementation and Extension to Low Magnitudes. Seismological Research Letters, 80 (5), 817- 822. doi:
IASPEI (2013). Summary of magnitude working group recommendations on standard procedures for determining earthquake magnitudes from digital data P,
Kanamori, H. (1993). W-phase. Geophysical Research Letter, 20 (16), SN  0094-8276, 1691-1694, URL:
Kanamori, H., & Rivera, L. (2008). W-phase. Source inversion of w phase: speeding tsunami warning. Geophysical Journal International, 175(1), 222–238.
Lay, T., & Wallace, C. (1995). Modern global seismology. Academic press, ISBN: 9780127328706.
Lomax, A., & Michelini, A. (2005). Rapid determination of earthquake size for hazard warning. EOS Trans., AGU, 86(19), 185–189.
Lomax, A., & Michelini, A. (2009). Mwpd: A duration amplitude procedure for rapid determination of earthquake magnitude and tsunamigenic potential from p waveforms. Geophysical Journal International, 176(1), 200–214, 2008.03974.x.
Lomax, A., Michelini, A., & Piatanesi, A. (2007). An energy duration procedure for rapid determination of earthquake magnitude and tsunamigenic potential. Geophysical Journal International, 170(3), 1195–1209, DOI 10.1111/j.1365-246X.2007.03469.x, URL:
Newman, A.V., & Okal, E.A. (1998). Teleseismic estimates of radiated seismic energy: the e/m0 discriminant for tsunami earthquakes. J. Geophys. Res., 103(11), 26 885–26 898.
Okal, E.A., & Talandier, J. (1989). Mm: A variable period mantle magnitude. Journal of Geophysical Research: Solid Earth, 94(B4), 4169–4193, DOI 10.1029/JB094iB04p04169, URL-
Oliveira, C.S., Roca, A., & Goula, X. (2006). Assessing and Managing Earthquake Risk: Geo-scientific and Engineering Knowledge for Earthquake Risk Mitigation: developments, tools, techniques (Geotechnical, Geological and Earthquake Engineering). Springer, ISBN: 978-1-4020-3524-1.
Saul, J., & Bormann, P. (2007). Rapid estimation of earthquake size using the broadband P-wave magnitude mB. GeoForschungsZentrum Potsdam, Germany.
Scholz, C.H., Aviles, C.A., & Wesnousky, S.G. (1986). Scaling differences between large interplate and intraplate earthquakes. Bull. Seism. Soc. Am., 76(1), 65–70.
Sipkin, S.A. (1994). Rapid determination of global moment-tensor solutions. Geophysics Res. Lett., 21, 1667–1670.
Stein, S., & Wysession, M. (2002). An Introduction to Seismology, Earthquakes, and Earth Structure. Wiley Blackwell, ISBN: 978-0-86542-078-6.
Tsuboi, S. (2000). Application of Mwp to tsunami earthquake. Geophysical Research Letters, 27(19), 3105–3108, DOI 10.1029/2000GL011735, URL
Tsuboi, S., Abe, K., Takano, K., & Yamanaka, Y. (1995). Rapid determination of mw from broadband P waveforms. Bulletin of the Seismological Society of America, 85(2), 606–613. URL:
Tsuboi, S., Whitmore, PM., & Sokolowski, T.J. (1999). Application of Mwp to deep and teleseismic earthquakes. Bulletin of the Seismological Society of America, 89(5), 1345–1351.
Vassiliou, M.S., & Kanamori, H. (1982). The energy release in earthquakes. Bull. Seism. Soc. Am., 72(2), 371–387.
Weinstein, S.A., & Okal, E.A. (2005). The mantle wave magnitude mm and the slowness parameter theta: five years of real-time use in the context of tsunami warning. Bull. Seism. Soc. Am., 95(3), 779–799.
Wessel, P., & Smith, W.H.F. (1991). Free software helps map and display data. EOS, Transactions American Geophysical Union, 72(41), 441– 446.
Whitmore, P., Sokolowski, T., Tsuboi, S., & Hirshorn, B. (2002). Magnitude-dependent correction for Mwp. Science of Tsunami Hazards, 20(4), 187–192.
Wiemer, S. (2004). Earthquake statistics and earthquake prediction research.