### Development of an Extended Hara Model for Mw Determination of Moderate-Magnitude Earthquakes

*I Nyoman Sukanta, Widjojo A. Prakoso, Tommy Ilyas, Masyhur Irsyam*

**Abstract**:

This study discusses the evaluation of Hara’s model to

estimate seismic moment magnitude (M_{W}) by using teleseismic waveform

data, and then presents the development of an extended Hara model. Both models

use the maximum amplitude of displacement and epicenter distance, as well as

the duration of high-frequency energy radiation, of the vertical component of

earthquake P-wave records. Nineteen moderate-magnitude (5.0 £ M_{W}£ 7.0), shallow (depths £ 70 km), Sumatra subduction megathrust earthquake data

sets recorded by the KAPI seismograph station (Kappang, South Sulawesi) in 2010

and 2011 were used in this study. The analysis is performed to obtain the

maximum amplitude of displacement, epicenter distance, and the duration of

high-frequency energy radiation on the first arriving P-wave. The main results

show that Hara’s model (2007) overestimates M_{W} to be less than 7.0

compared with that obtained from the Global Centroid Moment Tensor (CMT)

catalog. The extended Hara model was developed with the use of the same basic

equation, and the resulting coefficients are α = 0.538792, β = 0.783840, γ =

0.242616, and δ = 4.929095. The mean and standard deviation of the difference

between the extended Hara model and the Global CMT catalog are 0.01 and 0.14,

respectively.

**Keywords**: Earthquake; Hara’s model; Moment magnitude (Mw); Sumatra subduction megathrust

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#### References

Bormann, P., (Ed.), 2002. IASPEI New Manual of Seismological Observatory Practice (NMSOP), Volume 1 and 2, GeoForschungsZentrum, Potsdam

Bormann, P., Saul, J., 2008. The New IASPEI Standard Broadband Magnitude mB. Seismological Research Letters, Volume 79(5), pp. 699–705

Bormann, P., Saul, J., 2009. A Fast, Non-saturating Magnitude Estimator for Great Earthquakes. Seismological Research Letters, Volume 80, pp. 808–816

Global Centroid Moment Tensor Catalog, Available at http:/ /www.globalcmt.org/

Hanks, T., Kanamori, H.,1979. A Moment Magnitude Scale. Journal of Geophysical Research, Volume 84(B5), pp. 2348–2350

Hara, T., 2007. Measurement of the Duration of High-frequency Energy Radiation and its Application to Determination of the Magnitudes of Large Shallow Earthquakes. Earth Planets Space, Volume 59, pp. 227–231

Kanamori, H., 1977. The Energy Release in Great Earthquakes. Journal of Geophysical Research, Volume 82(20), pp. 2981–2987

Kanamori, H., Rivera, L., 2008. Source Inversion of W phase: Speeding up Seismic Tsunami Warning. Geophysical Journal International, Volume 175(1), pp. 222–238

Lay, T., Wallace, T., 1995. Modern Global Seismology, Academic Press, California, USA

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, Volume 176, pp. 200–214

Meteorology, Climatology, and Geophysics Agency (BMKG), Earthquake Catalog, period 20062012

Tsuboi, S., Abe, K., Takano, K., Yamanaka, Y., 1995. Rapid Determination of Mw from Broadband P Waveforms. Bulletin of the Seismological Society of America, Volume 83, pp. 606–613

US Geological Survey, Available at http://earthquake.usgs.gov/hazards/products/