Gaidos and Nimmo say that the tidal forces from Jupiter can cause regions of ice near a fault or defect to move relative to one another. This relative motion causes frictional heating that increases the local temperature of the ice and makes it less viscous. This "warm ice", which is estimated to have a temperature of about 273 K, then flows upwards by a few tens of centimetres over the course of one tidal cycle. "We suggest that such motion over the course of many cycles could be responsible for the formation of structures such as ridge pairs," say the researchers. Their model predicts pockets of liquid water near the moon's surface, which would, however, refreeze within tens of years.