Thanks for the response,
No the water didn’t flow over the pond edge, it was about 4 ft from the top edge when the crevice formed. I had put sod down around the edge of the pond to slow water but it was not established as it had only been down 2 days. I have graded the area where the water flow occurred to attempt to mitigate future issues. The soil is vary porous where I live, I had the clay trucked in to line the pond. I filled the crevice post rain, I went out in the morning after the rain and found the issue and got out the hoe and rake to fill it. We’ve had a moderate rain since the issue and I found no sign of water intrusion at the same location so I might have succeeded in my grading fix.