Hypocentral cross-sections and arc-trench curvature
Main Article Content
Abstract
A method is shown for obtaining the center of curvature, or pole, as well as the points of inflection of arcuate features such as trenches, on a spherical Earth. This information is needed, among other things, for projecting hypocenters along the are or perpendicular to it, which is better for depicting the geometry of Wadati-Benioff zones than the traditional straight-line approach. As a reference, the basic expressions for arcuate hypocentral projections are also given. As an example, the poles and points of inflection for the Middle America Trench are obtained. Using these parameters, hypocentral cross-sections projected along the are and perpendicular to it for this region are shown. The advantage of such sections as compared to straight-line sections from thc litcrature is dcmonstrated.
Article Details
This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
References
BENIOFF, H., 1954. Orogenesis and deep crustal structure: Additional evidence from Seismology. Geol. Soc. Am. Bull., 65, 385-400. DOI: https://doi.org/10.1130/0016-7606(1954)65[385:OADCSE]2.0.CO;2
BEVIS, M., 1986. The curvature of Wadati-Benioff zones and the torsional rigidity of subducting plates. Nature, 323, 52-53. DOI: https://doi.org/10.1038/323052a0
BEVIS, M. and B. L. ISACKS, 1984. Hypocentral trend surface analysis: Probing the geometry of Benioff zones. J. Geophys. Res. 89, 6153-6170. DOI: https://doi.org/10.1029/JB089iB07p06153
BURBACH, G. V. C. FROHLICH, W. D. PENNINGTON and T. MATUMOTO, 1984. Seismicity and tectonics of the subducted Cocos Plate. J. Geophys. Res., 89, 7719-7735. DOI: https://doi.org/10.1029/JB089iB09p07719
BURBACH, G. V. and C. FROHLICH, 1986. Intermediate and deep seismicity and lateral structure of subducted lithosphere in the circum-Pacific region. Rev. of Geophys. 24, 833-874. DOI: https://doi.org/10.1029/RG024i004p00833
CAHILL, T. and B. L. ISACKS, 1992. Seismicity and shape of the subducted Nazca Plate. J. Geophys. Res. 97, 17503-17529. DOI: https://doi.org/10.1029/92JB00493
EKSTRÖM, G. and E. R. ENGDAHL, 1989. Earthquake source parameters and stress distribution in the Adak Island region of the Central Aleutian Islands, Alaska. J. Geophys. Res., 94, 15499-15519. DOI: https://doi.org/10.1029/JB094iB11p15499
ENGDAHL, E. R., S. BILLINGTON and C. KISSLINGER, 1989. Teleseismically recorded seismicity before and after the May 7, 1986, Andreanof islands, Alaska, earthquake. J. Geophys. Res., 94, 15481-15498. DOI: https://doi.org/10.1029/JB094iB11p15481
HANUS, V. and J. VANEK, 1978. Subduction of the Cocos Plate and deep active fracture zones of Mexico, Geofísica Internacional, 17, 14-53. DOI: https://doi.org/10.22201/igeof.00167169p.1978.17.1.974
ISACKS, B. L., J. OLIVER and L. R. SIKES, 1968. Seismology and the new global tectonics. J. Geophys. Res., 73, 5855-5899. DOI: https://doi.org/10.1029/JB073i018p05855
ISACKS, B. L. and M. BARAZANGI, 1977. Geometry of Benioff zones: Lateral segmentation and downward bending of the subducted lithosphere. In: M. Talwani and W. C. Pitman III (Editors), Island arcs, deep sea trenches, and back-arc basins. American Geophysical Union, Washington, 470 pp. DOI: https://doi.org/10.1029/ME001p0099
JARRARD, R. D., 1986. Relations among subduction parameters. Rev. Geophys, 24, 217-284. DOI: https://doi.org/10.1029/RG024i002p00217
KAO, H. and W-P. CHEN, 1994. The double seismic zone in Kuril-Kamchatka: The tale of two overlapping single zones. J. Geophys. Res. 99, 6913-6930. DOI: https://doi.org/10.1029/93JB03409
KAWAKATSU, H., 1986. Downdip tensional earthquakes beneath the Tonga Arc: A double seismic zone? J. Geophys. Res., 91, 6432-6440. DOI: https://doi.org/10.1029/JB091iB06p06432
McCAFREY, R., 1992. Oblique plate convergence, slip vectors, and forearc deformation. J. Geophys. Res., 97, 8905-8915. DOI: https://doi.org/10.1029/92JB00483
PARDO, M., 1993. Características sismotectónicas de la subducción de las placas de Rivera y Cocos en el sur de México. Ph. D. dissertation. Universidad Nacional Autónoma de México, México, D.F.
PONCE, L., R. GAULON, G. SUAREZ and E. LOMAS, 1992. Geometry and state of stress of the downgoing Cocos Plate in the Istmus of Tehuantepec, Mexico. Geophys. Res. Let. 19, 773-776. DOI: https://doi.org/10.1029/92GL00437
PRESS, W. H., B. P. FLANNERY, S. A. TEUKOLSKY and W. T. VETTERLING, 1986. Numerical Recipes. Cambridge University Press, Cambridge, U. K., 818 pp.
SUAREZ, G. and D. COMTE, 1993. Comment on "Seismic coupling along the Chilean subduction zone" by B. W. Tichelaar and L. R. Ruff. J. Geophys. Res. 98, 15825-15828. DOI: https://doi.org/10.1029/93JB00234
TAYLOR, B. and G. D. KARNER, 1983. On the evolution of marginal basins. Rev. of Geophys. Spac. Phys. 21, 1727-1741. DOI: https://doi.org/10.1029/RG021i008p01727
TURCOTTE, D. L. and G. SCHUBERT, 1982. Geodynamics applications of continuum physics to geological problems. John Wiley and Sons, New York, 450 pp.
YAMAOKA, K. and Y. FUKAO, 1987. Why do island arcs form cusps at their junction? Geology, 15, 34-36. DOI: https://doi.org/10.1130/0091-7613(1987)15<34:WDIAFC>2.0.CO;2
WESSE, P. and W. H. F. SMITH, 1991. Free software helps map and display data. EOS Trans. AGU, 72, 441, 445-446. DOI: https://doi.org/10.1029/90EO00319
WYLIE, C. R. and L. C. BARRET, 1982. Advanced Engineering Mathematics. McGraw-Hill Book Company, New York, 1103 pp.