Estructura cortical en el Istmo de Tehuantepec, México, usando ondas convertidas
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Abstract
The crustal thickness in the Isthmus of Tehuantepec is estimated on the basis of converted Sp waves. The quality factor Qs for the crust beneath the seismic stations is also evaluated. Data were read from analog smoked paper seismograms, recorded in 1986 as part of a microearthquake field program. Average crustal parameters are as follows: Depth to Conrad Discontinuity: 22 ± 2.3 km; Depth to Moho 36 ± 3.2 km. These results suggest a typical continental structure under the Isthmus of Tehuantepec. Qs was estimated for two different relationships: Qp = Qs and Qp = 2Q8 . Average results are Qs = 76 and Qs = 130, respectively.
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References
AKI, K., 1980. Attenuation of shear waves in the litho-sphere. J. Geophys. Res., 85, 6496-6504. DOI: https://doi.org/10.1029/JB085iB11p06496
BÅTH, M. and R. STEFANSSON, 1966. S-P conversion at the base of the crust. Annali Geofis., XIX, 119-130.
BÅTH, M., 1979. Introduction to Seismology. Second Revised Edition. Birkhauser Verlag, 428 pp. DOI: https://doi.org/10.1007/978-3-0348-5283-8
BURBACH, G. V., C. FROHLICH, W. D. PENNINGTON, y T. MATUMOTO, 1984. Seismicity and Tectonics of the Subducted Cocos. Plate. J. Geophys. Res., 89, 7719-7735. DOI: https://doi.org/10.1029/JB089iB09p07719
CASE, J. E. y T. L. HOLCOMBE, 1980. Geologic-tectonic map of the Caribbean region. U. S. Geological Survey Miscellaneous Investigations, map I-1100.
CASTRO, R. R., 1980. Un modelo de Ia corteza terrestre para el sur de México mediante el uso de sismos profundos. Tesis Profesional, Facultad ·de Ingeniería, UNAM, 75 pp.
CERVENY, V. y R. RAVINDRA, 1971. Theory of seismic head waves. University of Toronto Press, 312 pp. DOI: https://doi.org/10.3138/9781442652668
CHIU, J., B. L. ISACKS y R. K. CARDWELL, 1986. Studies of crustal converted waves using short-period seismograms recorded in the Vanuatu island arc. Bull. Seism. Soc. Am., 76, 177-190. DOI: https://doi.org/10.1785/BSSA0760010177
COOK, K. L., S. T. ALGERMISSEN y J. L. COSTAIN, 1962. The status of Ps converted waves in crustal studies. J. Geophys. Res., 67, 4769-4778. DOI: https://doi.org/10.1029/JZ067i012p04769
DE LA FUENTE, M. E., M. MENA y C. L. V. AIKEN, 1991. Carta gravimétrica de Ia República Mexicana. Escala 1:3,000,000., INEGI, México.
GUZMAN, M., 1985. The triple junction of the North America, Cocos, and Caribbean Plates: seismicity and tectonics. M. Sc. Thesis. The University of Texas at Austin, 67 pp.
JORDAN, T. H. y L. N. FRAZER, 1975. Crustal and upper mantle structure from Sp phases. J. Geophys. Res., 80, 11, 1504-1518. DOI: https://doi.org/10.1029/JB080i011p01504
LEE, W. H. y J. C., LAHR, 1978. A computer program for determining hypocenter, magnitude and first motion pattern of local earthquakes. USGS Open File Report, 7-311.
MILLAN, M., 1989. Atenuación sísmica en el Centro Sur de México. Tesis de Maestría, Posgrado en Geofísica, UACPyP, Instituto de Geofísica, UNAM, 122 pp.
MOLINA, R., J. URRUTIA y R. VAN DER VOO, 1991. Concordant paleomagnetic directions from Tehuantepec Isthmus. Constrains for the Neogene evolution of the North America-Caribbean plate boundary. (Pre-impreso enviado para publicación a Geophys. Res. Lett.).
MOLNAR, P. y L. R. SYKES, 1969. Tectonics of the Caribbean and Middle America regions from local mechanisms and seismicity. Geol. Soc. Am. Bull., 80, 1639-1684. DOI: https://doi.org/10.1130/0016-7606(1969)80[1639:TOTCAM]2.0.CO;2
NUÑEZ-CORNU, F. J., 1988. Oaxaca: Análisis de Ia Estructura y Ia Sismicidad. Serie Investigación No. 4. Comunicaciones Técnicas. Instituto de Geofísica, UNAM.
PACHADZHANOVA, G. N., 1962. Study of transformed waves of Sp type during deep Afghan earthquakes (en ruso). Trudy Akad. Nauk Tadzkih SSR, Dushanbe, 10, 108-124.
PADILLA y SANCHEZ, R., 1986. Post Paleozoic tectonics of norteastern Mexico and its role in the evolution of the Gulf of Mexico. En: J. Urrutia Fucugauchi. Ed., Dynamics and evolution of the lithosphere: results and perspectives of geophysical research in Mexico, part A. Geofísica Internacional, 25, 157-206. DOI: https://doi.org/10.22201/igeof.00167169p.1986.25.1.804
PONCE, L., R. GAULON, G. SUAREZ y E. LOMAS, 1992. Geometry and state of stress of the downgoing Cocos plate in the isthmus of Tehuantepec, Mexico. Geophys. Res Lett., 19, 773-776. DOI: https://doi.org/10.1029/92GL00437
SACKS, I. S. y J. A. SNOKE, 1977. The use of converted phases to infer the depth of the lithosphere-asthenosfere boundary beneath South America. J. Geophys. Res., 82, 2011-2017. DOI: https://doi.org/10.1029/JB082i014p02011
SALVADOR, A., 1988. Late Triassic-Jurasic paleogeography and origin of Gulf of Mexico basin: Reply. Amer. Assoc. Petrol. Geol. Bull., 72, 11, 1419-1422. DOI: https://doi.org/10.1306/703C99BA-1707-11D7-8645000102C1865D
SATO, H., 1990. Unfied approach to amplitude attenuation and coda excitation in the randomly inhomogeneous lithosphere. PAGEOPH, 132. DOI: https://doi.org/10.1007/BF00874359
SMITH, W. D., 1970. S to P conversion as an aid to crustal studies. Geophys. J. R. Astrom. Soc., 19, 513-519. DOI: https://doi.org/10.1111/j.1365-246X.1970.tb00156.x
SUAREZ G. y L. PONCE, 1986. Interplate seismicity and crustal deformation in central Mexico. (abs.) EOS, Trans. Am. Geophys. Union, 67, 1114.
VINIEGRA, F., 1971. Age and evolution of salt basins of southeastern Mexico, Amer. Assoc. Petr. Geol. Bull., 55, 478-494. DOI: https://doi.org/10.1306/5D25CF6B-16C1-11D7-8645000102C1865D
YOUNG, G. B. y L. W. BRAILE, 1976. A computer program for the application of the Zeoppritz's amplitude equations and knott's energy equations. Bull. Seism. Soc. Am., 66, 1881-1885. DOI: https://doi.org/10.1785/BSSA0660061881
YUN-YU, D., 1965. Sp phases and the crustal thickness of China, Acta Geophys. Sinica, 14, 168-172.