Resumen

SORIA-CABALLERO, Diana Cinthia; GOMEZ-CALDERON, Daniel Alberto  y  GARDUNO-MONROY, Víctor Hugo. Paleoseismological analysis of El Malpaso - El Salto fault, north Michoacán, Mexico. Bol. Soc. Geol. Mex [online]. 2021, vol.73, n.2, 00009.  Epub 31-Ene-2022. ISSN 1405-3322.  https://doi.org/10.18268/bsgm2021v73n2a181220.

The El Malpaso - El Salto fault is a structure with en échelon geometry, composed of six main segments which combined has a length of 28 km. This fault belongs to the western sector of the Morelia-Acambay Fault System and affects Miocene - Pleistocene volcanic deposits related to the Cuitzeo ignimbrite and El Tzirate Volcanic Complex (18 and < 1.5 Ma, respectively). The landscape expression of this fault and the recent occurrence of earthquakes of moderate magnitude in the zone indicate that the studied fault could have important tectonic activity. The paleoseismic analysis of this work led us to estimate long-term slip rates (geologic SR) of 0.086 ± 0.015 mm/year and recurrence intervals of 10021 ± 1221 years, considering a total vertical displacement between 80 and 100 cm. According to empirical relationships resolvedfor the MASF, if the fault broke along its entire length, it would have the capacity to produce events with maximum magnitudes (MW) of 6.6 to 7.3, similar to the maximum magnitude reported for other faults in the Morelia- Acambay Fault System. In the study zone, the El Malpaso-El Salto fault has analogous characteristics (such as geometry, dimensions, direction, movement and potentiality) to a neighbor parallel fault named La Alberca-Teremendofault, located3 km southeast of the El Malpaso-El Salto fault trace. Bothfaults are favorably oriented to the current stress field (NW-SE extension) and their listric geometries suggest a probable interaction between them during a rupture event. The interaction with otherfaults of the same system could modify the estimated recurrence interval and maximum expected magnitude; also faults interactions increase the fault's hazard, therefore its study is important for the seismic risk assessment in central México. Also, more detailed studies are necessary to evaluate the activity of the western part of the Morelia Acambay Fault System.

Palabras llave : Paleoseismology; El Malpaso-El Salto fault; Morelia-Acambay Fault System; seismic hazard.

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