We study the relative importance of interplate and intraslab earthquakes in the seismic hazard of Mexico City by analyzing accelerograms recorded at the hill-zone site of CU (1964–2012) and the lake-bed site of SCT (1985–2012). Amax exceeded 6 gal during 20 earthquakes at CU during this period. Of these, eight were intraslab events so that the exceedance rate of Amax ≥ 6 gal from both types of earthquakes is roughly about the same. The estimated return period of Amax of 30 gal from the two types of earthquakes is ∼100 yrs. If we consider high-frequency (2.5–8.5 Hz) acceleration (AmaxHF) at CU, then the top 7 out of the 20 events are all intraslab earthquakes. Even at the lake-bed site of SCT, the AmaxHF values are, generally, associated with intraslab earthquakes. It follows that the risk from both types of earthquakes to low-rise construction in the city needs careful assessment.

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