Análisis de los esfuerzos tectónicos de la crisis sísmica
de 2010 en Haití
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Publication date
2014
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Sociedad Geológica de España
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Abstract
El evento de Mw=7 del 12 de enero 2010 provocó una crisis sísmica en el sur de Haití, que duró 3 meses. Se ha realizado un análisis de inversión de esfuerzos de los mecanismos focales del evento principal y 50 réplicas. El evento principal fue generado por un falla de buzamiento 64ºN y dirección N084Eº con una componente principal de deslizamiento lateral-izquierda y una componente inversa. Las réplicas se han generado por fallas inversas puras ENE-OSO situadas en la zona de interacción entre estructuras compresivas orientadas NO-SE y de desgarre orientadas E-O. Estas réplicas han sido activadas por un régimen de esfuerzos compresivo uniaxial muy homogéneo orientado con σ1 horizontal según N017ºE ±10º. La ausencia de ruptura en superficie indica que el origen de las réplicas son fallas ciegas orientadas N097º-117ºE. Los datos de deformación superficial intersísmica obtenidos a partir de velocidades derivadas de GPS para la zona epicentral muestran una desviación angular de ≈30º respecto a la orientación de σ1 obtenidos del análisis de esfuerzos. Esta desviación sugiere que una parte significativa de la energía elástica acumulada a lo largo de las estructuras de tendencia E-O no fue liberada durante la crisis sísmica de 2010.
The Mw=7 event of the January 12th, 2010 triggered a seismic crisis in the southern Haiti that continued for 3 months. The epicenter was located in an E-W oriented transpressive plate boundary where E-W trending left-lateral strike-slip and NW-SE trending compressive structures coexist (i.e., strain partitioning).We carried out the stress inversion analysis over the focal mechanisms of the main event and 50 aftershocks. The main event was generated by a N084Eº 64º N-dipping fault with both a main left-lateral slip component and a reverse component. The aftershocks have been generated by ENEWSW pure reverse faults located in the area of interaction between the NWSE compressive structures and E-W strike-slip structures. These aftershocks have been activated by a very homogeneous uniaxial compressive stress regime with a σ1 horizontal trending 017º±10º. The absence of surface rupture indicates that the sources of the aftershocks are blind thrusts oriented 097º-117º. The interseismic surface convergence, derived from GPS velocities, shows an angular deviation of ≈30° related to the orientation of σ1 derived from the stress inversion analysis. This deviation strongly suggests that a significant part of the elastic energy accumulated along the E-W trending structures was not released during seismic crisis of 2010.
The Mw=7 event of the January 12th, 2010 triggered a seismic crisis in the southern Haiti that continued for 3 months. The epicenter was located in an E-W oriented transpressive plate boundary where E-W trending left-lateral strike-slip and NW-SE trending compressive structures coexist (i.e., strain partitioning).We carried out the stress inversion analysis over the focal mechanisms of the main event and 50 aftershocks. The main event was generated by a N084Eº 64º N-dipping fault with both a main left-lateral slip component and a reverse component. The aftershocks have been generated by ENEWSW pure reverse faults located in the area of interaction between the NWSE compressive structures and E-W strike-slip structures. These aftershocks have been activated by a very homogeneous uniaxial compressive stress regime with a σ1 horizontal trending 017º±10º. The absence of surface rupture indicates that the sources of the aftershocks are blind thrusts oriented 097º-117º. The interseismic surface convergence, derived from GPS velocities, shows an angular deviation of ≈30° related to the orientation of σ1 derived from the stress inversion analysis. This deviation strongly suggests that a significant part of the elastic energy accumulated along the E-W trending structures was not released during seismic crisis of 2010.