Retrospective Estimation of the Hypocentre and Possible Early Warning for the November 12, 2017 Mw 7.3 Sarpol-e Zahab Earthquake in Western Iran

An effective Earthquake Early Warning System (EEWS) has to provide accurate estimates of the location and magnitude of an earthquake that has the potential to cause destructive ground motions. All this must happen within a few seconds after the first P-wave is detected by recording stations and before the arrival of strong S and surface waves. The largest earthquake (Mw 7.3) of the past century in the Zagros region (Iran) occurred on November 12, 2017 and was felt in several neighbouring countries; nevertheless, no EEWS was operating in the region. In this short article, an evolutionary real-time location estimation method (but retrospectively examined in the current study) based on the combination of the Voronoi diagram and Kalkan [1-3] algorithms has been used to simulate the potential of an EEWS to estimate the Sarpol-e Zahab earthquake's hypocentre. The employed algorithms use information on the successive triggering of stations by the P wave, from the first station (for which the estimate has low accuracy) up to a maximum of three stations (for which the estimate has acceptable accuracy). The depth of the earthquake is then determined using the arrival time of the S wave. The estimated hypocentre is in good agreement with offline reports by BHRC [4]. Moreover, an EEWS would ensure a meaningful warning time. As the main finding of the present study, for many locations and major cities, a time alert of more than 20 s for strong shaking (macroseismic intensity VI or above) locations and many tens of seconds for weaker shaking are estimated. Therefore, the establishment of an EEWS should be