Abstract:Following a destructive earthquake,timely and effective early warning is essential for reducing casualties and mitigating damage. In this study,warning timeliness is defined as the time interval between the onset of the earthquake—or the arrival of the first seismic wave—and the issuance of the initial alert by the earthquake early warning (EEW) system. As a critical metric for evaluating EEW system performance,timeliness directly affects the size of the warning blind zone and the time available for evacuation within the warning region. Thus,minimizing alert latency and optimizing delay control are central technical challenges in EEW systems. This paper investigates the fundamental principles and system architecture of EEW,with particular emphasis on the key factors influencing warning timeliness. Based on this analysis,it proposes strategies and core methodologies for controlling and improving timeliness. Furthermore,practical recommendations and measures are presented to ensure the efficiency and reliability of EEW systems,thereby enhancing their overall effectiveness in disaster risk reduction.