Abstract: Horizontal earthquake load has been generally assumed as the decisive role in damaging structures. According to our field investigation of damage to chimneys, it is shown that this traditional idea is not correct and the vertical seismic load does play the major role in the damage. Besides, the damage mechanism of multiple peripheral cracks on brick chimneys is described. Based on literature 1, both the maximum value of the horizontal seismic load and the minimum value of the vertical seismic load are computed for all damage patterns of chimneys: inclined cracks, dislocation, and fractured section near the top of the chimney in order to show that the vertical seismic load plays a major role in damage to chimneys, as mentioned above. For multiple peripheral cracks of brick chimney, the damage mechanism is also explained by computation.Continuous attenuation of longitudinal wave in transmission is considered, and so its computation formulas are not exactly the same as those in reference 1.