INTERPRETATION OF SMALL TO MODERATE SEISMICITY UNDER IRAZÚ VOLCANO
DOI:
https://doi.org/10.15359/rgac.58-1.7Keywords:
Irazú volcano, seismicity, focal mechanism, normal faultsAbstract
Historically, Irazú volcano has experienced sporadic volcano-tectonic seismicity. Based on this seismic activity, we have calculated a total of 7 focal mechanisms using the polarity of first arrivals, and have calculated stress inversion using the PTB method. The results indicate that the seismic activity is between 0-6 km deep, mainly in the W flank of the volcanic massif. Focal mechanisms show a diverse cinematics, the angles of the planes have an average of 55°, and the direction of inclination is toward the SWW. Stress inversion suggests a pure extension with a value of R’= 0,5. Therefore, the depth of the seismic events and the average angle of the planes makes us suppose that the brittle-ductile transition is above the one theoretically established. We suggest that the seismic source under the Irazú Volcano is directly related to the presence of magma near the surface, which causes the thinning of the crust and the related normal faults.
References
Allmendinger, R., Reilinger, R. y Loveless, J. (2007). Strain and Rotation Rate from GPS in Tibet, Anatolia, and the Altiplano. Tectonics, 26(TC3013), 1-18. doi:10.1029/2006TC002030.
Alvarado, G. E. (1993). Volcanology and Petrology of Irazú Volcano, Costa Rica. Kiel: Univ. Kiel.
Alvarado, G. E. (2011). Los volcanes de Costa Rica: Geología, historia, riqueza natural y su gente. San José: EUNED.
Alvarado, G. E., y Schmincke, H. U. (2013). The 1723 A.D. Violent Strombolian and Phreatomagmatic Eruption at Irazú Volcano, Costa Rica. Revista Geológica de América Central, 48, 41-61.
Alvarado, G. E., Carr, M., Turrin, B., Swisher, C., Schmincke, H., y Hudnut, K. (2006). Recent volcanic history of Irazú volcano, Costa Rica: Alternation and mixing of two magma batches, implying at least two intracrustal chambers. En Rose, W., Bluth, G., Carr, M., Ewert, J., Patino, L., y Vallance, J. Natural Hazards in Central America, 412, pp. 259-276. Geological Society of America Special Paper. doi:10.1130/2006.2412(14).
Anderson, E. M. (1951). The Dynamics of Faulting, Etc. (Revised.). Edinburgh, London.
Angelier, J. (2002). Inversion of earthquake focal mechanisms to obtain the seismotectonic stress IV - a new method free of choice among the nodal planes. Geophysical Journal International, 150, 588-609.
Angelier, J., Bergerat, F., Dauteuil, O. y Villemin, T. (1997). Effective tension-shear relationships in extensional fissure swarms, axial rift zone of northeastern Iceland. Journal of Structural Geology, 19, 673-685. doi:10.1016/S0191-8141(96)00106-X.
Barquero, R., Mora, M., Madrigal, L., Vargas, I., Arias, F. y Soto, G. (1995). Resumen anual de sismos y actividad volcánica en Costa Rica durante 1994. OVSICORI [Informe Interno].
Bott, M. P. (1959). The mechanics of oblique slip faulting. Geological Magazine, 96, 109-117.
Buck, R. W., Einarsson, P. y Brandsdóttir, B. (2006). Tectonic stress and magma chamber size as controls on dike propagation: Constraints from the 1975–1984 Krafla rifting episode. Journal of Geophysical Research, 111(B12404), 1-15. doi:10.1029/2005JB003879.
Carey, E. y Brunier, B. (1974). Analyse théorique d'un modèle mécanique élémentaire aplié à l'étude d'une population de failles. Comptes Rendus de l'Académie des Sciences Paris, 279, 891-894.
Clark, S., Reagan, M., y Trimble, D. (2006). Tephra deposits for the past 2600 years from Irazú volcano, Costa Rica. En Rose, W., Bluth, G., Carr, M., Ewert, J., Patino, L., y Vallance, J. Natural Hazards in Central America, 412, pp. 225-234 Geological Society of America Special Paper. doi:10.1130/2006.2412(12).
Collettini, C. y Sibson, R. H. (2001). Normal faults, normal friction? Geology, 29, 927-930. doi:10.1130/0091-7613(2001)0292.0.CO;2.
Dauteuil, O., Angelier, J., Bergerat, F., Verrier, S. y Villemin, T. (2001). Deformation partitioning inside a fissure swarm of the northern Iceland rift. Journal of Structural Geology, 23, 1359-1372. doi:10.1016/S0191-8141(01)00002-5.
Day, W. C., Dickerson, R. P., Potter, C. J., Sweetkind, D. S., San Juan, C. A., Drake, R. M. y Fridrich, C. J. (1998). Bedrock geologic map of the Yucca Mountain area, Nye County, Nevada. [Mapa]. Escala 1:24000. U.S. Geological Survey Miscellaneo Investigations Series Map. Nevada, EE.UU. I-2627.
Delvaux, D., Moeys, R., Stapel, G., Petit, C., Levi, K., Miroshnichenko, A., Ruzhich, V. y San'kov, V. (1997). Paleostress reconstructions and geodynamics of the Baikal region, central Asia, Part 2. Cenozoic rifting. Tectonophysics, 282(1), 1-38.
Fernández, E., Barquero, J., Barboza, V., Van Der Laat, R., Malavassi, E., Sáenz, R., Marino, T. y Martínez, M. (1994). Estado de los volcanes. Boletín de Vulcanología. OVSICORI-UNA [Informe Interno].
Ferrill, D. A. y Morris, A. P. (2003). Dilational normal faults. Journal of Structural Geology, 25, 183-196. doi:10.1016/S0191-8141(02)00029-9.
Ferrill, D. A., Sims, D. W., Waiting, D. J., Morris, A. P., Franklin, N. y Schultz, A. L. (2004). Structural framework of the Edwards Aquifer recharge zone in south-central Texas. Geological Society of America Bulletin, 116, 407-418. doi:10.1130/B25174.1.
Gephart, J. W. y Forsyth, D. W. (1984). An improved method for determining the regional stress tensor using earthquake focal mechanism data: Application to the San Fernando earthquake sequence. Journal of Geophysical Research, 89, 9305-9320.
Hayward, N. y Ebinger, C. (1996). Variations in the along-axis segmentation of the Afar rift system. Tectonics, 15, 244-257.
Jackson, J. A. y White, N. J. (1989). Normal faulting in the upper continental crust: Observations from regions of active extension. Journal of Structural Geology, 11, 15-36. doi:10.1016/0191-8141(89)90033-3.
Krushensky, R. D. (1972). Geology of Istarú Quadrangle. Washington D.C.: U.S. Geological Survey Bulletin, 1358.
Kusznir, N. J., y Park, R. G. (1984). Intraplate lithosphere deformation and the strength of the lithosphere. Geophysical Journal International, 79(2), 513-538.
Opheim, J. A. y Gudmundsson, A. (1989). Formation and geometry of fractures, and related volcanism, of the Krafla fissure swarm, northeast Iceland. Geological Society of America Bulletin, 101, 1608-1622. doi:10.1130/0016-7606(1989)1012.3.CO;2.
Pacheco, J. P., Muller, C., Avard, G., Cascante, M. y Martínez, M. (2015). Estado de los volcanes. Boletín de Vulcanología. OVSICORI [Informe Interno].
Reston, T. J. y Pérez-Gussinyé, M. (2007). Lithospheric extension from rifting to continental breakup at magma-poor margins: rheology, serpentinisation and symmetry. International Journal of Earth Sciences, 96, 1033-1046.
Rowland, J., Baker, E., Ebinger, C., Keir, D., Kidane, T., Biggs, J., Hayward, D. y Wright, T. (2007). Fault growth at a nascent slow-spreading ridge: 2005 Dabbahu rifting episode, Afar. Geophysical Journal International, 171, 1226-1246.
Ryan, W. F., Carbotte, S. M., Coplan, J. O., O'Hara, S., Melkonian, A., Arko, R., Weissel, R.A., Ferrini, V., Goodwillie, A., Nitsche, F., Bonczkowski, J. y Zemsky, R. (2009). Global Multi-Resolution Topography synthesis. Geochemistry Geophysics Geosystems, 10(Q03014), 1-9. doi:10.1029/2008GC002332.
Shelly, D. R. y Hill, D. P. (2011). Migrating swarms of brittle-failure earthquakes in the lower crust beneath Mammoth Mountain, California. Geophysical Research Letters, 38(L20307), 1-6. doi:10.1029/2011GL049336.
Ulloa, A., Campos-Fernández, C. S. y Rojas, L. (2013). Cueva los minerales, volcán Irazú, Costa Rica: descripción, mineralogía y origen. Revista Geológica de América Central, 48, 169-187.
Walsh, J. J. y Watterson, J. (1988). Dips of normal faults in British Coal Measures and other sedimentary sequences. Journal of the Geological Society, London, 145, 859-873.
Wright, T., Ebinger, C., Biggs, J., Ayele, A., Yirgu, G., Keir, D. y Stork, A. (2006). Magma-maintained rift segmentation at continental rupture in the 2005 Afar dyking episode. Nature, 422, 291-294.
Yamada, Y. y McClay, K. (2003). Application of geometric models to inverted listric fault systems in sandbox experiments. Paper 1: 2D hanging wall deformation and section restoration. Journal of Structural Geology, 25(9), 1551-1560. doi:10.1016/S0191-8141(02)00181-5.
Zoback, M. L. (1992). First- and second-order patterns of stress in the lithosphere: The World Stress Map Project. Journal of Geophysical Research, 97(B8), 11703-11728. doi:10.1029/92JB00132.
Downloads
Published
How to Cite
Issue
Section
License
Proposed policy for journals offering Open Access
Authors publishing their works in the Journal acknowledge and agree to the following terms:
a) Authors retain the copyrights to their works and guarantee the Journal the right to be the first to publish their works, under the Creative Commons License Attribution-NonCommercial-ShareAlike 4.0 International, CC BY-NC-SA 4.0 International (https://creativecommons.org/licenses/by-nc-sa/4.0/deed.es), which allows others to share works upon complying with the acknowledgment of authorship and mention of the Journal as the original publisher of the work.
b) Authors are permitted to separately establish additional agreements for the non-exclusive distribution of the official edition of the work published in the Journal (for example, authors may desire to place the work in an institutional repository or incorporate it into a book that is to published elsewhere) so long they acknowledgment to recognize the Journal as the original publisher. The aforementioned additional agreements must respect the terms of the non-profit character and sharing philosophy of the original license (CC BY-NC-SA 4.0 International, https://creativecommons.org/licenses/by-nc-sa/4.0/deed.es).
c) Authors are encouraged to archive the post-print or editor/PDF version in Open Access repositories.
REVGEO is licensed under https://creativecommons.org/licenses/by-nc-sa/4.0/deed.es
.svg_4.png){kind=logo}
_(1).png){kind=logo}
_(1)_(1)_(1)_1.png){kind=logo}
(2)(1)(1)(1).png){kind=logo}
