Inversion of site effects and Q factor using spectral ratios
DOI:
https://doi.org/10.3989/egeol.39591.047Keywords:
Earthquakes, Site effects, Attenuation, Amplification, Q factor, Costa RicaAbstract
Site effects and Q factor were inverted using the spectral ratio technique. The study area corresponds to central Costa Rica where the Earthquake Engineering Laboratory (INII-UCR) runs a strong motion network. The technique differs from the usual approach in that it makes use of a reference earthquake instead of a reference site. For that reason, the amplitude of the site effects that are obtained corresponds to the absolute amplification. The results indicate that stations located on soft sediment sites tend to have larger amplification values compared to other stations located on more compacted soils. The Q factor we obtained was frequency dependent with an approximate value of Q(f) = (131,6 ± 0,1)f (1,1 ± 0,2).
Downloads
References
Aki, K. (1967). Scaling Law of seismic spectrum. Journal of Geophysical Research, 72: 729-740. doi:10.1029/JZ072i004p01217
Brune, J.N. (1970). Tectonic stress and the spectra of seismic shear waves from earthquakes. Journal of Geophysical Research, 75: 4997-5009. doi:10.1029/JB075i026p04997
Christeson, G.L.; McIntosh, K.D. & Shipley, T.H. (2000). Seismic attenuation in the Costa Rica margin wedge: amplitude modeling of ocean bottom hydrophone data. Earth and Planetary Sciences Letters, 179: 391-405. doi:10.1016/S0012-821X(00)00118-7
Climent, A.; Taylor, W.; Ciudad Real, M.; Strauch, W.; Santana, G.; Villagran, M.; Dahle, A. & Bungum, H. (1994). Spectral strong motion attenuation in Central America. NORSAR Technical Report, August 1994, 46 pp.
DeShon, H.R, Schwartz, S.Y.; Bilek, S.L.; Dorman, L.M.; González, V.; Protti, J.M.; Flueh, E.R. & Dixon, T.H. (2003). Seismogenic zone structure of the southern Middle American Trench, Costa Rica. Journal of Geophysical Research, 108: 2491. doi:10.1029/2002JB002294
Fernández, M. & Montero, W. (2002). Fallamiento y sismicidad del área entre Cartago y San José, Valle Central de Costa Rica, Revista Geológica de América Central, 26: 25-37.
Goldstein, P.; Dodge, D. & Firpo, M. (1999). SAC2000: Signal processing analysis tools for seismologists and engineers. en: IASPEI International Handbook of Earthquake and Engineering Seismology part B (Lee W.H.K.; Kanamori H.; Jennings P.C. & Kisslinger C., eds.). Elsevier, New York, 1613-1614.
Husen, S.; Quintero, R.; Kissling, E. & Hacker, B. (2003). Subduction-zone structure and magmatic processes beneath Costa Rica constrained by local earthquake tomography and petrological modelling. Geophysical Journal International, 155: 11-32. doi:10.1046/j.1365-246X.2003.01984.x
Iwata, T. & Irikura, K. (1986). Separation of source, propagation, and site effects from observed S-waves. Journal of the Seismological Society of Japan, 39: 155-184.
Laporte, M. (1994). Respuesta dinámica de un depósito típico de la Ciudad de Cartago: comparación de un análisis teórico con observaciones de campo. VI Seminario Nacional de Geotecnia.
Montero, W. & Miyamura, S. (1981). Distribución de intensidades y estimación de los parámetros focales de los terremotos de Cartago de 1910, Costa Rica, América Central. Revista del Instituto Geográfico Nacional, 2: 9-34.
Moya, A.; Schmidt, V.; Segura, C.; Boschini, I. & Atakan, K. (1999). Empirical evaluation of site effects in the metropolitan area of San José, Costa Rica. 1999. Abstracts Volume, Ninth International Conference on Soil Dynamics and Earthquake Engineering. Bergen, Norway.
Moya, A. & Irikura, K. (2003). Estimation of site effects and Q factor using a reference event. Bulletin of the Seismological Society of America, 93: 1730-1745. doi:10.1785/0120020220
Pacheco, J.F.; Quintero, R.; Vega, F.; Segura J.; Jiménez, W. & González, V. (2006). The Mw 6.4 Damas, Costa Rica, Earthquake of 20 November 2004: Aftershocks and Slip Distribution. Bulletin of the Seismological Society of America, 96: 1332-1343. doi:10.1785/0120050261
Protti J.M.; MCnally, K.; Pacheco, J.; González, V.; Montero, C.; Segura, J.; Brenes, J.; Barboza, V.; Malavassi, E.; Güendel, F.; Simila, G.; Rojas, D.; Velasco, A.; Mata, A. & Schillinger, W. (1995): The March 25, 1990 (Mw = 7,0, ML = 6,8) earthquake of the entrance of Nicoya Gula, Costa Rica: Its prior activity, foreshocks, aftershocks, and triggered seismicity. Journal of Geophysical Research, 100: 20.345-20.358
Ramírez, R.; Santana, G. & Chacón, O. (1996). Mapa de amplificación sísmica del Valle Central, Costa Rica. Revista Geológica de América Central, 19: 37-55.
Sallares, V.; Dañobeitia J.J. & Flueh, E.R. (2001). Lithospheric structure of the Costa Rican Isthmus: Effects of subduction zone magmatism on an oceanic plateau. Journal of Geophysical Research, 106: 621-643. doi:10.1029/2000JB900245
Schmidt, V.; Moya, A.; Climent, C.; Rojas, W.; Boschini, I.; Lindholm, C.; Nadim, F.; Bungun, H. & Atakan, K. (2005). Microzonificación Sísmica de San José, Costa Rica. CD-ROM, Editorial Universidad de Costa Rica, San José, Costa Rica.
Schmidt, V.; Dahle, A. & Bungum, H. (1997). Costa Rican Spectral Strong Motion Attenuation. NORSAR Technical Report (RONDICA Project), Kjeller, Noruega. 47 pp.
Steidl, J.H.; Tumarkin, A.G. & Archuleta, R.J. (1996). What is a reference site? Bulletin of the Seismological Society of America, 86: 1733-1748.
Wessel, P. & Smith, W.H.F. (1998). New, improved version of the Generic Mapping Tools released, Eos, Transactions, American Geophysical Union, 79: 579. doi:10.1029/98EO00426
Downloads
Published
How to Cite
Issue
Section
License
Copyright (c) 2009 Consejo Superior de Investigaciones Científicas (CSIC)
This work is licensed under a Creative Commons Attribution 4.0 International License.
© CSIC. Manuscripts published in both the print and online versions of this journal are the property of the Consejo Superior de Investigaciones Científicas, and quoting this source is a requirement for any partial or full reproduction.
All contents of this electronic edition, except where otherwise noted, are distributed under a Creative Commons Attribution 4.0 International (CC BY 4.0) licence. You may read the basic information and the legal text of the licence. The indication of the CC BY 4.0 licence must be expressly stated in this way when necessary.
Self-archiving in repositories, personal webpages or similar, of any version other than the final version of the work produced by the publisher, is not allowed.
