Abstract

Dascher‐Cousineau et al. (2020) apply the so‐called foreshock traffic‐light system (FTLS) model proposed by Gulia and Wiemer (2019) to two earthquake sequences that occurred after the submission of the model: the 2019 Ridgecrest (Mw 7.1) and the 2020 Mw 6.4 Puerto Rico earthquakes. We show in this comment that the method applied by Kelian Dascher‐Cousineau et al. (2020) deviates in at least six substantial and not well‐documented aspects from the original FTLS method. As a consequence, they used for example in the Ridgecrest case only 1% of the data available to estimate b‐values and from a small subvolume of the relevant mainshock fault. In the Puerto Rico case, we document here substantial issues with the homogeneity of the magnitude scale that in our assessment make a meaningful analysis of b‐values impossible. We conclude that the evaluation by Dascher‐Cousineau et al. (2020) is misrepresentative and a not a fair test of the FTLS hypothesis.

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