What does Sbsdnc stand for?

Subsidence

Land sinks into the sea; opposite of uplifting. In weather forecasting terminology, this term refers to sinking motions of air masses. It could also refer to sinking motions within fluids or bodies of water. A downwards movement, especially a movement of foundations. The term is most often used to describe the movement of foundations on clay soil, when the soil shrinks due to becoming drier.