Floor that inflates under the sun

We have a floor outdoors mainly consisting of ciment. When it's sunny afternoon we noticed an inflation that looks like a bump. (A line of four meters in length 50 centimeters in width and 10 cm in height). When the sun becomes less aggressive the floor deflates becomes back to normal.
There was a 4.5 earthquake last year and a water leak (very big) three years ago. The floor is 70 years old and this is happening the first time this summer.