A detailed view on the effects of seismic activity on tank structures. As the use of aboveground and underground storage tanks (ASTs and USTs) continues to grow?with approximately 545 thousand in the US alone?the greatest threat to from AST and USTs is the contamination of groundwater, a vital source of drinking water throughout the world and one that close to half of Americans rely upon. These tanks suffer a great deal of strain during an earthquake, as a complicated pattern of stress affects them such that poorly designed tanks have leaked, buckled, or even collapsed during seismic events.