摘要：The Pátzcuaro–Acambay fault system (PAFS), located in thecentral part of the Trans-Mexican Volcanic Belt (TMVB), is delimited by anactive transtensive deformation area associated with the oblique subductionzone between the Cocos and North American plates, with a convergence speed of55mm yr−1 at the latitude of the stateof Michoacán, Mexico. Part of the oblique convergence is transferred tothis fault system, where the slip rates range from 0.009 to 2.78mm yr−1.This has caused historic earthquakes in Central Mexico,such as the Acambay quake (Ms=6.9) on 19 November 1912 with surfacerupture, and another in Maravatío in 1979 with Ms=5.6. Also,paleoseismic analyses are showing Quaternary movements in some faults, withmoderate to large magnitudes. Notably, this zone is seismically active, butlacks a dense local seismic network, and more importantly, its neotectonicmovements have received very little attention. The present researchencompasses three investigations carried out in the PAFS. First, theestimation of the maximum possible earthquake magnitudes, based on 316 faultlengths mapped on a 15m digital elevation model, by means of threeempirical relationships. In addition, the Hurst exponent Hw and itspersistence, estimated for magnitudes Mw (spatial domain) and for32 slip-rate data (time domain) by the wavelet variance analysis.Finally, the validity of the intrinsic definition of active fault proposedhere. The average results for the estimation of the maximum and minimummagnitudes expected for this fault population are 5.5≤Mw≤7.Also, supported by the results of H at the spatial domain, thispaper strongly suggests that the PAFS is classified in three different zones(western PAFS, central PAFS, and eastern PAFS) in terms of their roughness(Hw=0.7,Hw=0.5,Hw=0.8 respectively), showing different dynamics inseismotectonic activity and; the time domain, with a strongpersistence Hw=0.949, suggests that the periodicities of slip rates areclose in time (process with memory). The fractal capacity dimension (Db)is also estimated for the slip-rate series using the box-countingmethod. Inverse correlation between Db and low slip-rate concentrationwas observed. The resulting Db=1.86 is related to a lesser concentrationof low slip-rates in the PAFS, suggesting that larger faults accommodate thestrain more efficiently (length ≥3km). Thus, in terms offractal analysis, we can conclude that these 316 faults are seismicallyactive, because they fulfill the intrinsic definition of active faults forthe PAFS.
