Abstract
S wave amplitude spectra from shallow earthquakes with magnitudes ranging between 4.2 and 6.2 in the Zagros region of Iran that occurred between 1998 and 2008 are used to examine source parameters and site response of S waves. A generalized inversion scheme has been used to separate the source, propagation path, and local site effects from S wave spectra. For removing the trade-off between source and site terms and propagation effects (including geometric and anelastic attenuation), the spectral amplitudes of the records used were corrected for attenuation and geometrical spreading function using a path model proposed by Zafarani and Soghrat (Bull Seism Soc Am 102:2031–2045, 2012) for the region. We assume a Brune’s point source model to retrieve source parameters like corner frequency, moment magnitude, and high-frequency fall off coefficient, for each event. When the source spectra are interpreted in terms of Brune’s model, the average stress drops obtained are about 7.1 and 5.9 MPa (71 and 59 bars), respectively for the eastern and western Zagros regions. Stress drops range from 1.4 to 35.0 MPa (14 to 350 bars), with no clear dependence on magnitude. The results in terms of stress drop and S wave seismic energy indicate that the Zagros events are more similar to interplate earthquakes of western North America than to intraplate events of eastern North America. The method also provides us with site responses for all 40 stations individually and is an interesting alternative to other methods, such as the H/V method. A new empirical relationship between body-wave magnitudes and moment magnitude has been proposed for the Iranian plateau using derived seismic moment from the inversion.
Similar content being viewed by others
References
Aki K (1967) Scaling law of seismic spectrum. J Geophys Res 72:1217–1231
Ambraseys NN, Melville CP (1982) A history of Persian earthquakes. Cambridge University Press, London, p 219 pp
Anderson J, Hough S (1984) A model for the shape of the Fourier amplitude spectrum of acceleration at high frequencies. Bull Seism Soc Am 74:1969–1993
Andrews DJ (1986) Objective determination of source parameters and similarity of earthquakes of different size, earthquake source mechanics. American Geophysical Union, Washington, pp 259–67
Ansari A, Noorzad A, Zafarani H, Vahidifard H (2010) Correction of highly noisy strong motion records using modified wavelet de-noising method. Soil Dyn Earthq Eng 30:1168–181
Berberian M (1995) Master ‘blind’ thrust faults hidden under the Zagros folds: active basement tectonics and surface morphotectonics. Tectonophysics 241:193–224
Boatwright J, Fletcher J, Fumal T (1991) A general inversion scheme for source, site, and propagation characteristics using multiply recorded sets of moderate-sized earthquakes. Bull Seism Soc Am 81:1754–1782
Boore DM (2003) Simulation of ground motion using the stochastic method. Pure Appl Geophys 160:635–675
Brune J (1970) Tectonic stress and the spectra of seismic shear waves from earthquakes. J Geophys Res 75:4997–5009
Brune J (1971) Correction to Brune (1970). J Geophys Res 76:5002
Buiding and Housing Research Center (BHRC). Available from http://www.bhrc.ac.ir/portal/. Accessed May 2011
Castro R, Anderson JG, Singh SK (1990) Site response, attenuation, and source spectra of S waves along the Guerrero, Mexico subduction zone. Bull Seism Soc Am 80:1481–1503
Chen SZ, Atkinson GM (2002) Global comparisons of earthquake source spectra. Bull Seism Soc Am 92:885–95
Drouet S, Chevrot S, Cotton F, Souriau A (2008) Simultaneous inversion of source spectra, attenuation parameters, and site responses: application to the data of the French accelerometric network. Bull Seism Soc Am 98:198–219
Dutta U, Martirosyan A, Biswas N, Papageorgiou A, Combellick R (2001) Estimation of S-wave site response in Anchorage, Alaska, from weak-motion data using generalized inversion method. Bull Seism Soc Am 91:335–346
Dutta U, Biswas N, Martirosyan A, Papageorgiou A, Kinoshita S (2003) Estimation of earthquake source parameters and site response in Anchorage, Alaska from strong-motion network data using generalized inversion method. Phys Earth Planet Inter 137:13–29
Engdahl ER, Jackson JA, Myers SC, Bergman EA, Priestley K (2006) Relocation and assessment of seismicity in the Iran region. Geophys J Int 167:761–78
Harmsen SC (1997) Determination of site amplification in the Los Angeles Urban Area from inversion of strong-motion records. Bull Seism Soc Am 87:866–87
Hartzell S (1992) Site response estimation from earthquake data. Bull Seism Soc Am 82:2308–27
Harvard Seismology (2011) Centroid Moment Tensor (CMT) catalog search. www.seismology.harvard.edu/. Accessed May 2011
Hassani B, Zafarani H, Farjoodi J, Ansari A (2011) Estimation of site amplification, attenuation and source spectra of S-waves in the East-Central Iran. Soil Dyn Earthq Eng 31:1397–1413
Husid P (1967). Gravity effects on the earthquake response of yielding structures. Report of Earthquake Engineering Research Laboratory, California Institute of Technology, Pasadena, California
Iwata T, Irikura K (1988) Source parameters of the 1983 Japan Sea earthquake sequence. J Phys Earth 36:155–84
Lermo J, Chavez-Garcia F (1993) Site effect evaluation using spectral ratios with only one station. Bull Seism Soc Am 83:1574–94
Madariaga R (1976) Dynamics of an expanding circular fault. Bull Seism Soc Am 66:639–666
McCann MWJ, Shah HC (1979) Determining strong motion duration of earthquakes. Bull Seism Soc Am 69:1253–1265
Mirzaei Alavijeh, H. & Farzanegan, E., 1998. Specifications of the Iranian Accelerograph Network Stations Building and Housing, Research Center, Publication No. B-280.
Mirzaei Alavijeh H, Sinaiean F, Farzanegan E, Sadeghi Alavijeh ME (2007). Iran Strong Motion Network (ISMN) prospects and achievements. In: Proceedings of the fifth international conference on seismology and earthquake engineering, Tehran
Motazedian D (2006) Region-specific key seismic parameters for earthquakes in Northern Iran. Bull Seism Soc Am 96:1383–95
Mousavi M, Zafarani H, Noorzad A, Ansari A, Bargi KH (2007) Analysis of Iranian strong motion data using the specific barrier model. J Geophys Eng 4:1–14
National Earthquake Information Centre (NEIC). Available from http://earthquake.usgs.gov/regional/neic/. Accessed May 2011
Nowroozi A (2010) Probability of peak ground horizontal and peak ground vertical accelerations at Tehran and surrounding areas. Pure Appl Geophys 167:1459–1474
Ramsey LA, Walker RT, Jackson J (2008) Fold evolution and drainage development in the Zagros Mountains of Fars province, SE Iran. Basin Research 20:23–48
Salazar W, Sardina V, Cortina JD (2007) A hybrid inversion technique for the evaluation of source, path, and site effects employing S-wave spectra for subduction and upper-crustal earthquakes in El Salvador. Bull Seism Soc Am 97:208–221
Scholz CH, Aviles CA, Wesnousky SG (1986) Scaling differences between large interplate and intraplate earthquakes. Bull Seism Soc Am 76:65–70
Scordilis EM (2006) Empirical global relations converting MS and m b to moment magnitude. J Seismology 10:225–236
Shoja-Taheri J, Niazi M (1981) Seismicity of Iranian plateau and bordering regions. Bull Seism Soc Am 71:477–489
Shoji Y, Kamiyama M (2002) Estimation of local site effects by a generalized inversion scheme using observed records of ‘Small-Titan’. Soil Dyn Earthq Eng 22:855–864
Siddiqqi J, Atkinson GM (2002) Ground-motion amplification at rock sites across Canada as determined from the horizontal-to-vertical component ratio. Bull Seism Soc Am 92:877–884
Silva WJ, Abrahamson N, Toro G, Costantino C (1997). Description and validation of the stochastic ground motion model. Final report. Brookhaven National Laboratory, Associated Universities, Inc., Upton, New York
Sokolov VY, Bonjer KP, Oncescu M, Rizescu M (2005) Hard rock spectral models for intermediate-depth Vrancea (Romania) earthquakes. Bull Seism Soc Am 95:1749–1765
Soghrat MR, Khaji N, Zafarani H (2012) Simulation of strong ground motion in northern Iran using the specific barrier model. Geophys J Int 188:645–679
Talebian M, Jackson J (2004) A reappraisal of earthquake focal mechanisms and active shortening in the Zagros mountains of Iran. Geophys J Int 156:1–21
Trifunac MD, Lee VW (1973). EERL 73-03, Earthquake Engineering Research Laboratory, California Institute of Technology Pasadena, 1973-10 (370/T72/1973). 360 pp
Tramelli A, Galluzzo D, Del Pezzo E, Di Vito MA (2010) A detailed study of the site effects in the volcanic area of Campi Flegrei using empirical approaches. Geophys J Int 182:1073–1086
Vassiliou MS, Kanamori H (1982) The energy release in earthquake. Bull Seism Soc Am 72:371–387
Vernant F, Nilforoushan F, Hatzfeld D, Abbassi MR, Vigny C, Masson F, Bayer R, Nankali H, Martinod J, Ashtiani A, Tavakoli RF, Chery J (2004) Present-day crustal deformation and plate kinematics in the Middle East constrained by GPS measurements in Iran and northern Oman. Geophys J Int 157:381–398
Zafarani H, Mousavi M, Noorzad A, Ansari A (2008) Calibration of the specific barrier model to Iranian plateau earthquakes and development of physically based attenuation relationships for Iran. Soil Dyn Earthq Eng 28:550–76
Zafarani H, Noorzad A, Ansari A, Bargi K (2009) Stochastic modeling of Iranian earthquakes and estimation of ground motion for future earthquakes in Greater Tehran. Soil Dyn Earthq Eng 29:722–41
Zafarani H, Hassani B, Ansari A (2012) Estimation of earthquake parameters in the Alborz seismic zone, Iran using generalized inversion method. Soil Dyn Earthq Eng 42:197–218
Zafarani H, Soghrat MR (2012) Simulation of ground motion in the Zagros, Iran using the specific barrier model and stochastic method. Bull Seism Soc Am 102:2031–2045
Zare M, Bard PY, Ghafory-Ashtiany M (1999) Site characterizations for the Iranian strong motion network. Soil Dyn Earthq Eng 18:101–23
Acknowledgment
The authors acknowledge the Building and Housing Research Centre of Iran for providing them with the accelerograms and shear-wave velocities used in the current study.
Author information
Authors and Affiliations
Corresponding author
Appendices
Appendix A
Appendix B
Rights and permissions
About this article
Cite this article
Zafarani, H., Hassani, B. Site response and source spectra of S waves in the Zagros region, Iran. J Seismol 17, 645–666 (2013). https://doi.org/10.1007/s10950-012-9344-1
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10950-012-9344-1