Researchers at Caltech made the animations below which show the seasonal deformation and subsidence of Earth’s surface, respectively, as a result of groundwater extraction and refilling. This occurs when soil and earth layers are compacted and undergo subsidence due to the decrease of upward hydrostatic pressure balancing the weight of the layers.
Surface deformation and subsidence of Earth’s surface is measured using Interferometric Synthetic Aperture Radar (ISAR). ISAR is also used for natural hazard assessment. This includes applications to regions of volcanic, tectonic (e.g. faults and mountains), and construction activities.
So far the only way to get any information about the interior of rocky planets was from the moment of inertia which is related to a planets mass distribution. This only allowed to estimate if a planet has a mantle and what the estimated thicknesses of the core and mantle are. Of course, other (remote sensing) methods like potential (gravity and magnetic) fields can also give more information about a planets interior. However, the only solid way to determine the layer interface and their depth and thicknesses is seismic imaging, a popular technique used to image Earth’s subsurface and interior.
One can notice the depth of the ocean floor, on a global scale, ranges between -2000 and -6000 meters. In some regions though like the Pacific exceed this range and reach 11 kilometers below the sea surface. One such region is the deepest point on Earth, the Mariana trench as shown below followed by a map for a perspective of its location.