Does the ocean lose a great deal of water when a trench is formed?
If a trench suddenly forms a great deal of water does fill in the new volume created. However, the volume of the ocean is so great that the water filling in the trench is miniscule in comparison. Without doing any calculation, I would guess that if a new trench formed that is larger than the largest trench in the ocean, the ocean level might drop less than a millimeter. Also, the earth is in a “steady state,” meaning that for every trench formed, on average there is an equal volume of seafloor mountains created, and thus there would be no overall change in ocean volume. (Giora Proskurowski) How is the depth of a trench measured? In the past oceanographers would hang a big weight over the side of a ship and let it sink until it hit the bottom (when it hits the bottom there would be a change in the tension of the line). The oceanographers would know how much line they had let out, and thus the depth. These types of measurements are much more sophisticated today. Depth measurements can be
