The research aims to investigate the hazard of aftershocks of strong earthquakes occurred in Taiwan (1999/9/21, M7.3 Chi-Chi), China (2008/5/12, M7.9 Wenchuan), Japan (2011/3/31, M9.0 Tohoku) and USA (2019/7/6), respectively. To do so, a modification of the Reasenberg-Jones (RJ) model is proposed for time-related magnitudes. Although the gridding method is usually employed for portraying the spatial hazard, it may not work when a near real-time assessment of the hazard is needed with sparse data. Therefore, spatial distributions of the aftershock epicenters incorporated with tectonic structures are suggested, including single or mixture bivariate distributions. The original or modified RJ model together with spatial distributions then give space-time-magnitude models for the hazard of aftershocks after a strong main shock. The ROC curve-related criterion and probability gain are finally used to evaluate how well the space-time-magnitude models are for alarming forthcoming aftershocks.