Source Functions and Path Effects from Earthquakes in the Farallon Transform Fault Region, Gulf of California, Mexico that Occurred on October 2013
We determined source spectral functions, Q and site effects using regional records of body waves from the October 19, 2013 (Mw = 6.6) earthquake and eight aftershocks located 90 km east of Loreto, Baja California Sur, Mexico. We also analyzed records from a foreshock with magnitude 3.3 that occurred 47 days before the mainshock. The epicenters of this sequence are located in the south-central region of the Gulf of California (GoC) near and on the Farallon transform fault. This is one of the most active regions of the GoC, where most of the large earthquakes have strike–slip mechanisms. Based on the distribution of the aftershocks, the rupture propagated northwest with a rupture length of approximately 27 km. We calculated 3-component P- and S-wave spectra from ten events recorded by eleven stations of the Broadband Seismological Network of the GoC (RESBAN). These stations are located around the GoC and provide good azimuthal coverage (the average station gap is 39◦). The spectral records were corrected for site effects, which were estimated calculating average spectral ratios between horizontal and vertical components (HVSR method). The site-corrected spectra were then inverted to determine the source functions and to estimate the attenuation quality factor Q. The values of Q resulting from the spectral inversion can be approximated by the relations Q P = 48.1 1±1f 0:880:04 and QS = 135:4 1:1f ±0:580:03 and are consistent with previous estimates reported by Vidales-Basurto et al. (Bull Seism Soc Am 104:2027–2042, 2014) for the south-central GoC. The stress drop estimates, obtained using the ω2 model, are below 1.7 MPa, with the highest stress drops determined for the mainshock and the aftershocks located in the ridge zone. We used the values of Q obtained to recalculate source and site effects with a different spectral inversion scheme. We found that sites with low S-wave amplification also tend to have low P-wave amplification, except for stations BAHB, GUYB and SFQB, located on igneous rocks, where the P-wave site amplification is higher.
KeywordsEarthquakes in the Gulf of California source and path effects Farallon transform fault
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The operation of the RESBAN network has been possible thanks to the financial support of the Mexican National Council for Science and Technology (CONACYT) (projects CB-2011-01-165401(C0C059), G33102-T and 59216). This paper was prepared while the first author (RRC) was on sabbatical year in Caltech. We thank Prof. Gurnis for the support provided. Dr. Lenin Avila-Barrientos facilitated part of the spectral records used to calculate the site functions. Antonio Mendoza Camberos pre-process the data from the RESBAN network and Arturo Perez Vertti maintains and operates the stations. We thank Dr. Edwards and the anonymous reviewer for their careful revisions, comments and suggestions which help us to improve the manuscript. We also acknowledge the Editor, Dr. Thomas H.W. Goebel.
- Adams, D. A., & Abercrombie, R. E. (1998). Seismic attenuation above 10 Hz in southern California from coda waves recorded in the Cajon Pass borehole. Journal Geophysical Research, 103, 24257–24270.Google Scholar
- Aki, K. (1967). Scaling law of seismic spectrum. Journal Geophysical Research, 72, 1217–1231.Google Scholar
- Anderson, J. G. (1991). A preliminary descriptive model for the distance dependence of the spectral decay parameter in southern California. Bulletin of the Seismological Society of America, 81, 2186–2193.Google Scholar
- Anderson, J. G., & Hough, S. E. (1984). A model for the shape of the Fourier amplitude spectrum of acceleration at high frequencies. Bulletin of the Seismological Society of America, 74, 1969–1993.Google Scholar
- Andrews, D.J. (1986). Objective determination of source parameters and similarity of earthquakes of different size. In S. Das, J. Boatwright, C. H. Sholz (Eds.) Earthquake source mechanics. Washington, DC: American Psychological Union. doi: https://doi.org/10.1029/GM037p0259
- Atwater, T., & Stock, J. (1998). Pacific-North America plate tectonics of the Neogene Southwestern United States: An update. International Geologiy Review, 40, 375–402.Google Scholar
- Avila-Barrientos, L., & Castro, R. R. (2015). Site response of the NARS-Baja and RESBAN broadband networks of the Gulf of California, Mexico. Geoísica International, 55, 131–154.Google Scholar
- Boore, D. M. (1986). Short-period P- and S-wave radiation from large earthquakes: implications for spectral scaling relations. Bulletin of the Seismological Society of America, 76, 43–64.Google Scholar
- Brune, J. N. (1970). Tectonic stress and the spectra of seismic shear waves from earthquake. Journal Geophysical Research, 75, 4997–5009.Google Scholar
- Carbotte, S. M., Arko, R., Chayes, D. N., Haxby, W., Lehnert, K., O’Hara, S., et al. (2004). New integrated data management system for Ridge 2000 and MARGINS research. EOS Transactions, AGU, 85(51), 553. doi: https://doi.org/10.1029/2004EO510002.
- Castro, R. R., Anderson, J. G., & Singh, S. K. (1990). Site response, attenuation and source spectra of S waves along the Guerrero, México, subduction zone. Bulletin of the Seismological Society of America, 80, 1481–1503.Google Scholar
- Castro, R. R., & Avila-Barrientos, L. (2015). Estimation of the spectral parameter kappa in the region of the Gulf of California, Mexico. Journal of Seismology 19, 809–829. doi: https://doi.org/10.1007/s10950-015-9496-x.
- Castro, R. R., Pacor, F., Bindi, D., Franceschina, G., & Luzi, L. (2004). Site response of strong motion stations in the Umbria, Central Italy, region. Bulletin of the Seismological Society of America, 94, 576–590.Google Scholar
- Castro, R. R., Pacor, F., Puglia, R., Ameri, G., Letort, J., Massa, M., & Luzi, L. (2013). The 20 May, 2012 Emilia earthquake, Italy and the main aftershocks: S-wave attenuation, acceleration source functions, and site effects. Geophysical Journal International,. doi: https://doi.org/10.1029/2004GL019808.
- Castro, R. R., Pérez-Vertti, A., Mendez, I., Mendoza, A., & Inzunza, L. (2011a). Location of moderate size earthquakes recorded by the NARS-Baja array in the Gulf of California region between 2002 and 2006. Pure and Applied Geophysics, 168, 1279–1292.Google Scholar
- Castro, R. R., Valdes-Gonzalez, C., Shearer, P., Wong, V., Astiz, L., Vernon, F., et al. (2011b). The 3 August 2009 Mw 6.9 Canal de Ballenas region, Gulf of California, earthquake and its aftershocks. Bulletin of the Seismological Society of America, 101, 929–939.Google Scholar
- Clayton, R. W., Trampert, J., Rebollar, C. J., Ritsema, J., Persaud, P., Paulssen, H., et al. (2004). The NARS-Baja array in the Gulf of California R ift Zone. Margins Newsletter, 13, 1–4.Google Scholar
- Edwards, B., Michel, C., Poggi, V., & Fah, D. (2013). Determination of site amplification from regional seismicity: Application to the Swiss National Seismic Networks. Seismological Research Letters, 84, 611–621. doi: https://doi.org/10.1785/0220120176.
- Fenby, S. S., & Gastil, R.G. (1991). Geologic-Tectonic map of the Gulf of California and surrounding áreas. In J. P. Dauphin & B. T. Simoneit (Eds.), The Gulf and Penninsular provinces of the Californias (Vol. 47, pp. 79–83). Tulsa:American Association of Petroleum Geologist.Google Scholar
- Goff, J. A., Bergman, E. A., & Solomon, S. C. (1987). Earthquake source mechanism and transform fault tectonics in the Gulf of California. Journal Geophysical Research, 92, 10485–10510.Google Scholar
- Hauksson, E., & Shearer, P. M. (2006). Attenuation models (QP and QS) in three dimensions of the southern California crust: Inferred fluid saturation at seismogenic depths. Journal Geophysical Research, 111, B05302. doi: https://doi.org/10.1029/2005JB003947.
- Langston, C. A. (1977). Corvallis, Oregon, crustal and upper mantle receiver structure from teleseismic P and S waves. Bulletin of the Seismological Society of America, 67, 713–724.Google Scholar
- Lermo, J., & Chávez-García, F. J. (1993). Site effect evaluation using spectral ratios with only one station. Bulletin of the Seismological Society of America, 83, 1574–1594.Google Scholar
- Lizarralde, D., Axen, G. J., Brown, H. E., Fletcher, J. M., Gonzalez- Fernandez, A., Harding, A. J., et al. (2007). Variation in styles of rifting in the Gulf of California. Nature,. doi: https://doi.org/10.1038/nature06035.
- Lonsdale, P. F. (1989). Geology and tectonic history of the Gulf of California. The Eastern Pacific Ocean and Hawaii, Decade of North American geology (Vol. N, pp. 499–521). Denver, CO, USA: Geol. Soc. Am.Google Scholar
- López-Pineda, L., & Rebollar, C. J. (2005). Source characteristics of the Mw 6.2 Loreto earthquake of 12 march 2003 that occurred in a transform fault in the middle of the Gulf of California, Mexico. Bulletin of the Seismological Society of America, 95, 419–430.Google Scholar
- Munguía, L., Reichle, M., Reyes, A., Simons, R., & Brune, J. (1977). Aftershocks of the 8 July, 1975 Canal de las Ballenas, Gulf of California, earthquake. Geophysical Reseach Letters, 4, 507–509.Google Scholar
- Nagy, E. A., & Stock, J. M. (2000). Structural control on the continent-ocean transition in the Northern Gulf of California. Journal Geophysical Research, 105, 16251–16269.Google Scholar
- Nakamura, Y. (1989). A method for dynamic characteristics estimation of subsurface using microtremor on the ground surface. Report Railway Technical Research Institute, 30, 25–33.Google Scholar
- Nava-Sánchez, E. H., Gorsline, D. S., & Molina-Cruz, A. (2001). The Baja California peninsula borderland: structural and sedimentological characteristics. Sedimentary Geology, 144, 63–82. doi: https://doi.org/10.1016/S0037-0738(01)00135-X.
- Pacheco, J. F., & Sykes, L. R. (1992). Seismic moment catalog of large shallow earthquakes, 1900 to 1989. Bulletin of the Seismological Society of America, 82, 1306–1349.Google Scholar
- Phillips, W. S., & Aki, K. (1986). Site amplification of coda waves from local earthquakes in central California. Bulletin of the Seismological Society of America, 76, 627–648.Google Scholar
- Raoof, M., Hermann, R. B., & Malagnini, L. (1999). Attenuation and excitation of three-component ground motion in southern California. Bulletin of the Seismological Society of America, 89, 888–902.Google Scholar
- Rebollar, C. J., Quintanar, L., Castro, R. R., Day, S. M., Madrid, J., Brune, J. N., et al. (2001). Source characteristics of a 5.5 magnitude earthquake that occurred in the transform fault system of the Delfin Basin in the Gulf of California. Bulletin of the Seismological Society of America, 91, 781–791.Google Scholar
- Rebollar, C. J., Traslosheros, C., & Alvarez, R. (1985). Estimates of seismic wave attenuation in northern Baja California. Bulletin of the Seismological Society of America, 75, 1371–1382.Google Scholar
- Rodriguez-Lozoya, H. E., Quintanar, L., Ortega, R., Rebollar, C. J., & Yagi, Y. (2008). Rupture process of four medium-size earthquakes that occurred in the Gulf of California. Journal Geophysical Research, 113, B10301. doi: https://doi.org/10.1029/2007JB005323.
- Schlotterbeck, B. A., & Abers, G. A. (2001). Three-dimensional attenuation variations in southern California. Journal Geophysical Research, 106, 30719–30735.Google Scholar
- Singh, S. K., Apsel, R. J., Fried, J., & Brune, J. N. (1982). Spectral attenuation of SH waves along the Imperial fault. Bulletin of the Seismological Society of America, 72, 2003–2016.Google Scholar
- Stein, S., & Pelayo, A. (1991). Seismological constraints on stress in the oceanic lithosphere. Philosophical Transactions of the Royal Society of London A, 337, 53–72.Google Scholar
- Stock, J. M., & Hodges, K. V. (1989). Pre-Pliocene extension around the Gulf of California and the transfer of Baja California to the Pacific plate. Tectonics, 8, 99–115.Google Scholar
- Sumy, D. F., Gaherty, J. B., Kim, W.-Y., Diehl, T., & Collins, J. A. (2013). The mechanism of earthquakes and faultingin the southern Gulf of California. Bulletin of the Seismological Society of America, 103, 487–506.Google Scholar
- Tanioka, Y., & Ruff, L. (1997). Source time functions. Seismological Research Letters, 68, 386–400.Google Scholar
- Trampert, J., Paulsen, H., Van Wettum, A., Ritsema, J., Clayton, R., Castro, R., et al. (2003). New array monitors seismic activity near the Gulf of California in México, EOS. Transactions American Geophysical Union, 84, 29–32.Google Scholar
- Van Houtte, C., Ktenidou, O. J., Larkin, T., & Holden, C. (2014). Hard-site K0 (Kappa) calculations for Christchurch, New Zealand, and comparison with local ground motion prediction models. Bulletin of the Seismological Society of America, 104, 1899–1913.Google Scholar
- Vidales-Basurto, C. A., Castro, R. R., Huerta, C. I., Sumy, D. F., Gaherty, J. B., & Collins, J. A. (2014). An attenuation study of body-waves in the south-central region of the Gulf of California, México. Bulletin of the Seismological Society of America, 104, 2027–2042.Google Scholar
- Wessel, P., & Smith, W. H. F. (1998). New, improved version of generic mapping tools released. EOS Transactions, AGU, 79(47), 579.Google Scholar
- Winkler, K. W., & Nur, A. (1982). Seismic attenuation: effects of pore fluids and frictional sliding. Geophysics, 47, 1–15.Google Scholar
- Zhang, X., Paulsen, H., Lebedev, S., & Meier, T. (2007). Surface wave tomography of the Gulf of California. Geophysical Reseach Letters, 34, L15305. doi: https://doi.org/10.1029/2007GL030631.