HR: 0800h
AN: T41B-02    [Abstracts]
TI: Macroseismological And Paleoseismological Studies In The Active Segments Of The Morelia Acambay Fault System, Mexico
AU: * Garduño-Monroy, V H
EM: vgmonroy@zeus.umich.mx
AF: Departamento de Geologia y Mineralogia-Universidad Michoacana de San Nicolas de Hidalgo, Edif. U, Ciudad Universitaria, Morelia, Mic 58060, Mexico
AU: Rodriguez-Pascua, M A
EM: marodpas@ceu.es
AF: Universidad de San Pablo CEU, Ctra.Boadilla del Monte, Km.5300, Madrid, 28668, Spain
AU: Israde-Alcantara, I
EM: aisrade@zeus.umich.mx
AF: Departamento de Geologia y Mineralogia-Universidad Michoacana de San Nicolas de Hidalgo, Edif. U, Ciudad Universitaria, Morelia, Mic 58060, Mexico
AU: Hernandez- Madrigal, V M
EM: vittoriomanuel@yahoo.it
AF: Departamento de Geologia y Mineralogia-Universidad Michoacana de San Nicolas de Hidalgo, Edif. U, Ciudad Universitaria, Morelia, Mic 58060, Mexico
AB: Paleoseismological studies along several faults of the Morelia-Acambay system show clear evidence of its seismicity. In the Acambay region, four seismic events were identified during the Pliocene Pleistocene; two linked to large sub aquatic landslides, and two to liquefaction processes. The two seismic events associated to slumps were also recognized in the Ixtlahuaca, Mexico, region; meaning these were relevant seismic events at a regional level. Their magnitudes were above 5 degrees. Because these latter events are located in the same column, they could be of aid in knowing recurrence periods. In the southern portion of the Lake of Patzcuaro region a collapse was identified generating a rock avalanche nearly 29,000 years ago. This collapse is associated to an earthquake of magnitude above 7 degrees, which decreased the lake's extension and resulted in morphology of small hummocks. The Purhepecha term Jaracuaro means "place that emerges" and is the name of a former island where Pre Hispanic settlements occurred. The island is exclusively made up of lacustrine sequences that rose above 50m in height, georadar and vertical electrical signal (VES) studies do not reveal intrusive bodies associated to this deformation. Isosists of the 1845 and 1858 seismic events were reconstructed in the modified Mercalli scale through several historical studies in a number of municipalities in the State of Michoacan. The results indicate isosistes of IX degrees in Patzcuaro, where the earthquake caused the collapse of the basilica. During the 1858 earthquake the water level in the southern portion of the Lake of Patzcuaro raised over 2m and the destruction of 120 adobe houses is related to the generation of a tsunami. This seismic event is being characterized in wells and ditches dugs around Patzcuaro Lake. The region of Patzcuaro has experienced a number of magmatic and tectonic events that undoubtedly modified the conditions of the lake regarding its sedimentology and anthropogenic development.
DE: 7221 Paleoseismology (8036)
DE: 8036 Paleoseismology (7221)
SC: Tectonophysics [T]
MN: 2007 Joint Assembly