Affected by Helan piedmont fault and the geological structure in the area,the seismic wave forms recorded by Yinchuan station show distortions,and the distortions cause the azimuth anomaly.

• 认为受贺兰山山前断裂构造和震中所在地地质构造的影响，银川台记录到的地震波形发生畸变，而波形畸变又造成了方位异常。