The growth rate of the tearing mode instability excited by the lower hybrid and/or ion cyclotron turbulence at the Earth's magnetopause has been reinvestigated on the basis of recent observations. The growth time of the tearing mode is found to be of the order of 10 s in the case of lower hybrid turbulence, whereas it becomes 2 s in case of ion cyclotron background turbulence. Thus the background turbulence, as an external driving source, can efficiently produce rapid and variable reconnection rates. ¿ American Geophysical Union 1992