A performance evaluation of the detection and classification algorithm for earthquake early warning 2(tS–tP) was conducted to test its reliability and robustness. The Seismic Alert System of Mexico (SASMEX) has used this algorithm since 1991. The algorithm estimates the rate of seismic energy released during two times the (tS–tP) period. Based on the energy released, it estimates an empirical magnitude range related to mb. Depending on the estimated mb, either preventive or public alerts are issued. In this article, post facto tests are presented for 61 earthquakes for which SASMEX issued an alert. The algorithm was also tested on 31 earthquakes (Mw>6.0) that occurred in the Mexican subduction zone from 1985 to 2014. These earthquakes occurred outside the coverage of the SASMEX instruments at the time. This dataset includes the 19 September 1985 Mw 8.1 Michoacán earthquake and the 9 October 1995 Mw 8.0 Colima event. The algorithm was tested also on two great earthquakes: the 22 February 2010 Mw 8.8 Maule, Chile, earthquake and the 11 March 2011 Mw 9.0 Tohoku, Japan, event. The results of the evaluation of 144 acceleration records of the 61 earthquakes detected from the SASMEX network indicate that 92% of the accelerograms of earthquakes with mb>6.0 have errors in the prediction of magnitude of less than ±0.5, and 83% for mb>5.5. Also, the tests conducted on the 59 acceleration records of 31 earthquakes with Mw≥6.0 indicate that in all cases, with the exception of one strong‐motion record, the events are classified as Mw≥6.0. Thus, the algorithm shows a high level of reliability and robustness. Although the algorithm underestimates the magnitudes of large earthquakes, these events are identified and classified as Mw≥6.0. Thus, an alert would be issued for these great earthquakes.
Electronic Supplement:Table of earthquake parameters, performance of Seismic Alert System of Mexico (SASMEX), and specific performance evaluation of the 2(tS–tP) algorithm.