Large low-shear-velocity provinces

Large Low-Shear-Velocity Provinces (or "LLSVPs") are big, slowly-moving regions deep inside the Earth's mantle. The Earth's mantle is the layer of rock between the crust (the surface of the Earth that we live on) and the core. When you shake one end of a tube filled with water, the water has to travel all the way down the tube before the other end shakes. This is like how the LLSVPs move—if there's a big earthquake in one part of the world, it takes a while before the LLSVPs move in response to that earthquake.