A huge crack has appeared in a road next to the railway line at the Folkestone Warren.
The whole width of the road, which is next to the railway line to Dover, appears to have split.
One driver said she had a scare when her car "bounced down" over the steep drop.
Network Rail had already implemented a 20mph (32kmh) speed limit in the area after an earlier movement of the promenade.
A spokesman for Network Rail said it was "aware of uneven surfaces" at the Folkestone Warren promenade and it had sensors installed to monitor the situation.