HR: 0800h
AN: V11C-0749    [Abstracts]
TI: A Preliminary Study of Seismicity at Ceboruco, Volcano, Nayarit, Mexico
AU: * Sanchez, J J
EM: jjsanchez@pv.udg.mx
AF: Centro de Sismologia y Volcanologia de Occidente, Univ. de Guadalajara, Av. Universidad 203, Pueto Vallarta, Jal 48280, Mexico
AU: Nunez-Cornu, F J
AF: Centro de Sismologia y Volcanologia de Occidente, Univ. de Guadalajara, Av. Universidad 203, Pueto Vallarta, Jal 48280, Mexico
AU: Suarez-Plascencia, C
AF: Centro de Sismologia y Volcanologia de Occidente, Univ. de Guadalajara, Av. Universidad 203, Pueto Vallarta, Jal 48280, Mexico
AU: Trejo-Gomez, E
AF: Centro de Sismologia y Volcanologia de Occidente, Univ. de Guadalajara, Av. Universidad 203, Pueto Vallarta, Jal 48280, Mexico
AB: Ceboruco Volcano is located northwestern of Tepic-Zacoalco graben (Jalisco, Mexico). Its volcanic activity can be divided in four eruptive cycles differentiated by their volcano explosivity index (VEI) and chemical variations as well. As a result of andesitic effusive activity, during the first cycle the "paleo-Ceboruco" edifice was constructed. The end of this cycle is defined by a plinian eruption (VEI is estimated between 3 and 4) which occurred some 1020 years ago and formed the external caldera. During the second cycle an andesitic dome extruded in the interior of the caldera. The dome, called Dos Equis, collapsed and formed the internal caldera. The third cycle is represented by andesitic lava flows which partially cover the northern and south-southwestern part of the edifice. The last cycle is represented by historic andesitic lava flows located in the southwestern flank of the volcano. In February 2003 as part of an agreement with Nayarit Civil Defense a seismic station was installed in the SW flank of the volcano. The station is equipped with a Marslite (lennartz) digitizer with a 3DLe 1Hz. seismic sensor. Detection system is based on a STA/LTA recording algorithm. More than 2000 small earthquakes have been attributed to various local sources, and some of this earthquakes are possibly located beneath Ceboruco volcano. A preliminary classification separates high frequency and low frequency seismic events. The sources of high frequency earthquakes appear to be distributed as evidenced from waveforms variety and changing S-P arrivals separations. The low frequency seismic events also show varying signatures and some of them exhibit extended coda, including some monochromatic character.
DE: 7280 Volcano seismology (8419)
DE: 8105 Continental margins: divergent (1212, 8124)
DE: 8419 Volcano monitoring (7280)
DE: 8428 Explosive volcanism
DE: 8488 Volcanic hazards and risks
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting