Sinkhole urban areas due to water main breaks or sewer collapses when old pipes give way. They can also occur from the overpumping and extraction of groundwater and subsurface fluids. Sinkholes can also form when natural water-drainage patterns are changed and new water-diversion systems are developed. Some sinkholes form when the land surface is changed, such as when industrial and runoff-storage ponds are created; the substantial weight of the new material can trigger a collapse of the roof of an existing void or cavity in the subsurface, resulting in development of a sinkhole. Sinkholes tend to occur in karst landscapes. Karst
The Heart Is a Lonely Hunter (Once Upon a Time) that Graham helped fill a void for her character, commenting that his loss "was not easy for [Regina]. That’s why, when she crushes his heart, there’s a tear coming out of her eye. She didn’t want to do it, but she had no choice — almost like how she had no choice to kill her father. I’m not saying I agree with it, but for the character, it’s what she had to do." Parrilla also cited "The Heart Is a Lonely Hunter" as the first episode where viewers see "how the two worlds collided," a reference to Regina's ability to