The Performance of the Foreshock Traffic Light System for the Period 2016-2024

Strong earthquakes are followed by countless smaller events, whose number decays with time: a posteriori, we call them aftershocks. Sometimes, this sequence is interrupted by a larger event, and the “aftershocks” turn out to be foreshocks. In 2019, Gulia and Wiemer have proposed traffic light tool, named the Foreshock Traffic Light System (FTLS), that can discriminate between foreshocks and aftershocks, by monitoring the size distribution of events closely. The model successfully passed the first near real-time test (Gulia et al., 2020). A new version of the code, that can run in real-time, has been recently developed; since testing is the essence of the scientific method and is fundamentally important in seismicity forecast evaluation, we here show the performance of the new version of the FTLS through pseudo-prospective and, when possible, real-time tests on the available seismic sequences between 2016 and 2024.