Abstract：Phase velocity error caused by position error of microtremor observation array is computed under different conditions such as two different dispersive phase velocity models of Rayleigh wave, three kinds of radius, 19 kinds of observation position mode and 6 types of position error. The results show that phase velocity error exists even when it is free of position error for limited number of observation sites. The maximum error is almost 3 times as large as the minimum one. The effect of position error is not so clear when it is less than 1%.The phase velocity error from 1% position error is about 0.4% while it increases almost proportionally to position error in the range of 1% and 10% with a ratio of 2.5.
