Precursory seismicity of the 1994 eruption of Popocatépetl Volcano,Central Mexico |
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| Authors: | Servando De la Cruz-Reyna Izumi Yokoyama Alicia Martínez-Bringas Esteban Ramos |
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| Institution: | (1) Instituto de Geofísica. C. Universitaria, Universidad Nacional Autónoma de México, Mexico, 04510, DF, Mexico;(2) Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan;(3) Centro Nacional de Prevención de Desastres CENAPRED, Mexico, 04360, DF, Mexico;(4) Dirección General de Protección Civil del Estado de México, Carr. México-Pachuca, km 37, Tecamac, Méx. 55740, Mexico |
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| Abstract: | Popocatépetl Volcano is located in the central Mexican Volcanic Belt, within a densely populated region inhabited by over
20 million people. The eruptive history of this volcano indicates that it is capable of producing a wide range of eruptions,
including Plinian events. After nearly 70 years of quiescence, Popocatépetl reawakened in December 21, 1994. The eruptive
activity has continued up until the date of this submission and has been characterized by a succession of lava dome growth-and-destruction
episodes, similar to events that have apparently been typical for Popocatépetl since the fourteenth century. In this regime,
the episodes of effusive and moderately explosive activity alternate with long periods of almost total quiescence. In this
paper we analyze five years of volcano-tectonic seismicity preceding the initial eruption of the current episode. The evolution
of the V-T seismicity shows four distinct stages, which we interpret in terms of the internal processes which precede an eruption
after a long period of quiescence. The thermal effects of a magma intrusion at depth, the fracturing related to the slow development
of magma-related fluid pathways, the concentration of stress causing a protracted acceleration of this process, and a final
relaxation or redistribution of the stress shortly before the initial eruption are reflected in the rates of V-T seismic energy
release. A hindsight analysis of this activity shows that the acceleration of the seismicity in the third stage asymptotically
forecast the time of the eruption. The total seismic energy release needed to produce an eruption after a long period of quiescence
is related to the volume of rock that must be fractured so imposing a characteristic threshold limit for polygenetic volcanoes,
limit that was reached by Popocatépetl before the eruption. |
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| Keywords: | Popocatépetl volcano Volcano-tectonic earthquakes Reawakening of volcanic activity Accelerating seismic energy release Eruption precursors |
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