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
A Void constraint to the original, avoiding the most commonly used letter of the alphabet. This precludes the use of words normally considered essential such as "je" ("I"), "et" ("and") and "le" (masculine "the") in French, as well as "me," "be," and "the" in English. The Spanish version contains no "a", which is the second most commonly used letter in the Spanish language (first being "e"), while the Russian version contains no о. The Japanese version does not use い ("i") at all. "A Void"'s plot follows a group of individuals looking for a missing companion, Anton Vowl. It is in part