How useful are earthquake early warnings? The case of the 2017 earthquakes in Mexico city

The paper presents the results of a cross-sectional study regarding participants' perception on the SASMEX system performance following the two earthquakes that hit Mexico City on 7 and 19 September in 2017. The approach has been the application of questionnaires to a sample size of n = 2400. The survey was conducted from 4 October-20 November 2017. The questions included in the questionnaire were based on the criteria of the effectiveness of early warning systems proposed by the United Nations-International Strategy for Disaster Reduction (UN-ISDR). Some of the key conclusions were the following: {a}. Deficiencies have been highlighted in relation to ‘risk knowledge’, ‘monitoring and warning’, ‘dissemination & communication’, and ‘response capability’ of the system; {b}. The results have highlighted the need to issue the warning time to the residents of the city (i.e., the time between the moment the siren sounds and the actual ground shaking); knowing the warning time may be of great value to people during the seismic emergency, at least for the case of Mexico City, however, this may require further research; {c}. More generally, the SASMEX and any earthquake early warning (EEW) system should be people-centred.