What does the seabed landform look like?

Just like on land, the underwater world has mountains, plains, and deep canyons. This world is not as peaceful and peaceful as people imagine or as it appears on the surface. On the contrary, it is the most active and turbulent area on earth. Earthquakes and volcanic activities are frequent, forming high mountains and ridges, but everything is hidden under the sea.

The topography of the seabed is the same as that of land, including mountains, plateaus, basins, hills, etc. The seafloor landforms can be roughly divided into three parts: continental shelf, continental slope and ocean floor according to the undulating morphological characteristics of the ocean floor. The continental shelf refers to the flat, shallow seabed extending from land to ocean. The continental slope is the steeper slope between the continental shelf and the deep seafloor. The ocean floor is the main part of the ocean, with positive topography such as ocean ridges, ridges, and submarine plateaus; and negative topography such as trenches, troughs, and deep-sea basins.

Ocean basin: The main part of the ocean. A basin in which the ocean floor is concave and divided by ridges or seafloor rises. It has a large area, a round or oval shape, a flat bottom, and a depth of 3,000-6,000 meters (mostly 4,000-5,000 meters). Covered by deep-sea sediments, mainly chemical sedimentation and biological sedimentation.

Undersea mountain range: also known as "sea ridge" or "sea ridge". A long and narrow plateau at the bottom of the deep sea. The length can reach tens of thousands of kilometers, the width is 1,000-3,000 kilometers, and the height is 2,000-4,000 meters. Individual peaks emerge from the water and become islands, such as the Azores Islands in the Atlantic Ocean and Ascension Island in the South Atlantic Ocean. The submarine mountain range in the central Atlantic Ocean runs from north to south. The direction of the mountain range is consistent with the outline of the ocean, forming an S-shape. The Pacific Ridge is distributed in the central part, stretching for more than 10,000 kilometers from north to south. The Indian Ocean ridges are distributed in a herringbone shape.

Trench: A long and narrow depression zone in the ocean with a water depth of more than 6,000 meters. It can be thousands of kilometers long, generally about a hundred kilometers wide, and has steep slopes on both sides. Trench is often distributed together with ocean ridge. The ridges emerge from the water and become islands. In the western and northern Pacific Ocean, a series of islands are arc-shaped and form island arcs. Trench is generally on the convex surface of an island arc, adjacent to the coastal mountains of the mainland or close to the island, on the edge of the ocean. Most trenches are located in the Pacific Ocean, especially on the west coast. The deepest trench in the world is the Mariana Trench southeast of the Mariana Islands in the Western Pacific. It is 11,034 meters deep, 2,550 kilometers long, and has an average width of 70 kilometers. The trench distribution area is the most unstable zone in the earth's crust, with frequent volcanoes and earthquakes. Xiangshan Port is located in the north of Xiangshan County, Zhejiang Province, extending into the land from northeast to southwest, with a length of about 50 kilometers and a width of only 6 kilometers. There are Liuheng Islands outside the harbor as a barrier. The situation is dangerous and it is one of the excellent harbors.

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