The Commander Basin (alternately Komandorsky Basin) is located between the Shirshov Ridge and the Kamchatka Peninsula. Its southern boundary is the Aleutian arc (see figure) and occupies the western part of the Bering Sea. The Kamchatka Strait provides a deep water access to the basin from the southwest.
The basins sedimentary cover is less than 2 km thick. In the southwestern portion of the basin near the Ulakahn Fault, linear magnetic anomalies associated with the Early Miocene have been identified. The magnetic anomalies support a sequential opening of the Commander Basin resulting from stresses on the interface between the Eurasian and Pacific plates. The structures of the Bering Sea floor at the Commander Basin were created 17 to 21 Million years before the present. [1]
The Commander Basin floor is a horizontal plain 3800–3900 m deep. It is covered with 2000–6000 m of sediment overlying an oceanic crust which is 12–14 km thick. [2] Active spreading in the Commander Basin occurred between 40 and 10 Myr ago, with subduction of the basin floor along the Ulakhan fault underneath the Kamchatka peninsula. There are four major fracture zones in the basin and magnetic lineations have been detected in the basin. Except in the southern end of the basin, the spreading center has been subducted. [3]
The water in the basin circulates in a cyclonic gyre, with the western Kamchatka Current flowing southward along the Kamchatka Peninsula. The northward leg of the gyre is outside of the Commander Basin, and is carried by the Bering Slope Current, which flows along the edge of the continental shelf at the eastern edge of the Aleutian Basin. To the south, the Commander Basin connects to the North Pacific through the 4.4 km wide, 4,420 meter deep Kamchatka Strait and the 2.0 km wide, 2,000 meter deep Near Strait. [4]
The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about 85,133,000 km2 (32,870,000 sq mi). It covers approximately 17% of Earth's surface and about 24% of its water surface area. It is known to separate the "Old World" of Africa, Europe, and Asia from the "New World" of the Americas in the European perception of the World.
The Bering Sea is a marginal sea of the Northern Pacific Ocean. It forms, along with the Bering Strait, the divide between the two largest landmasses on Earth: Eurasia and the Americas. It comprises a deep water basin, which then rises through a narrow slope into the shallower water above the continental shelves. The Bering Sea is named after Vitus Bering, a Danish navigator in Russian service, who, in 1728, was the first European to systematically explore it, sailing from the Pacific Ocean northward to the Arctic Ocean.
The Commander Islands, Komandorski Islands, or Komandorskie Islands are a series of islands in the Russian Far East located about 175 km (109 mi) east of the Kamchatka Peninsula in the Bering Sea. Treeless and sparsely populated, the islands consist of Bering Island, Medny Island and fifteen islets and rocks. The largest of the latter are Tufted Puffin Rock (Kamen Toporkov or Ostrov Toporkov), 15 ha, and Kamen Ariy, which are between 3 km (1.9 mi) and 13 km (8.1 mi) west of the only settlement, Nikolskoye. Administratively, the Commanders compose the Aleutsky District of the Kamchatka Krai in Russia.
The Alaska Peninsula is a peninsula extending about 497 mi (800 km) to the southwest from the mainland of Alaska and ending in the Aleutian Islands. The peninsula separates the Pacific Ocean from Bristol Bay, an arm of the Bering Sea.
The Kuril–Kamchatka Trench or Kuril Trench is an oceanic trench in the northwest Pacific Ocean. It lies off the southeast coast of Kamchatka and parallels the Kuril Island chain to meet the Japan Trench east of Hokkaido. It extends from a triple junction with the Ulakhan Fault and the Aleutian Trench near the Commander Islands, Russia, in the northeast, to the intersection with the Japan Trench in the southwest.
Many major earthquakes have occurred in the region of the Kamchatka Peninsula in far eastern Russia. Events in 1737, 1923 and 1952, were megathrust earthquakes and caused tsunamis. There are many more earthquakes and tsunamis originating from the region.
The Aleutian Trench is an oceanic trench along a convergent plate boundary which runs along the southern coastline of Alaska and the Aleutian islands. The trench extends for 3,400 kilometres (2,100 mi) from a triple junction in the west with the Ulakhan Fault and the northern end of the Kuril–Kamchatka Trench, to a junction with the northern end of the Queen Charlotte Fault system in the east. It is classified as a "marginal trench" in the east as it runs along the margin of the continent. The subduction along the trench gives rise to the Aleutian Arc, a volcanic island arc, where it runs through the open sea west of the Alaska Peninsula. As a convergent plate boundary, the trench forms part of the boundary between two tectonic plates. Here, the Pacific Plate is being subducted under the North American Plate at a dip angle of nearly 45°. The rate of closure is 7.5 centimetres (3 in) per year.
The Kamchatka Current is a cold-water current flowing southwestward from the Bering Strait, along the Siberian Pacific coast and the Kamchatka Peninsula. A portion of this current then becomes the Oyashio Current while the remainder joins the warmer North Pacific Current.
The 2006 Kamchatka earthquake occurred on April 21, 2006 at 12:25 PM local time. This shock had a moment magnitude of 7.6 and a maximum Mercalli intensity of X (Extreme). The hypocenter was located near the coast of Koryak Autonomous Okrug at an estimated depth of 22 km, as reported by the International Seismological Centre. This event caused damage in three villages and was followed by a number of large aftershocks. Two M6.6 earthquakes struck on April 29 at 16:58 UTC and again on May 22 at 11:12 UTC. These earthquakes caused no deaths; however, 40 people were reported injured.
The following outline is provided as an overview of and introduction to Oceanography.
The Temperate Northern Pacific is a biogeographic region of the Earth's seas, comprising the temperate waters of the northern Pacific Ocean.
The Aleutian Basin is an oceanic basin located beneath the southwestern Bering Sea. While the northeastern half of the Bering Sea is situated over the North American Plate in relatively shallow waters, the Aleutian Basin comprises an oceanic plate, which is the remaining portion of the Kula Plate that was predominantly subducted beneath the North American Plate.
The Aleutian Islands, also called the Aleut Islands or Aleutic Islands and known before 1867 as the Catherine Archipelago, are a chain of 14 large volcanic islands and 55 smaller islands. Most of the Aleutian Islands belong to the U.S. state of Alaska, but some belong to the Russian federal subject of Kamchatka Krai. They form part of the Aleutian Arc in the Northern Pacific Ocean, occupying a land area of 6,821 sq mi (17,666 km2) and extending about 1,200 mi (1,900 km) westward from the Alaska Peninsula toward the Kamchatka Peninsula in Russia, and act as a border between the Bering Sea to the north and the Pacific Ocean to the south. Crossing longitude 180°, at which point east and west longitude end, the archipelago contains both the westernmost part of the United States by longitude and the easternmost by longitude. The westernmost U.S. island in real terms, however, is Attu Island, west of which runs the International Date Line. While nearly all the archipelago is part of Alaska and is usually considered as being in the "Alaskan Bush", at the extreme western end, the small, geologically related Commander Islands belong to Russia.
The Shirshov Ridge is located on the eastern border of the Commander Basin below the Kamchatka Peninsula. It extends directly southward for a distance of 750 km toward the Aleutian arc in the eastern part of the Bering Sea.
The Pacific Ocean evolved in the Mesozoic from the Panthalassic Ocean, which had formed when Rodinia rifted apart around 750 Ma. The first ocean floor which is part of the current Pacific Plate began 160 Ma to the west of the central Pacific and subsequently developed into the largest oceanic plate on Earth.
The South China Sea Basin is one of the largest marginal basins in Asia. South China Sea is located to the east of Vietnam, west of Philippines and the Luzon Strait, and north of Borneo. Tectonically, it is surrounded by the Indochina Block on the west, Philippine Sea Plate on the east, Yangtze Block to the north. A subduction boundary exists between the Philippine Sea Plate and the Asian Plate. The formation of the South China Sea Basin was closely related with the collision between the Indian Plate and Eurasian Plates. The collision thickened the continental crust and changed the elevation of the topography from the Himalayan orogenic zone to the South China Sea, especially around the Tibetan Plateau. The location of the South China Sea makes it a product of several tectonic events. All the plates around the South China Sea Basin underwent clockwise rotation, subduction and experienced an extrusion process from the early Cenozoic to the Late Miocene.
The Aleutian subduction zone is a 2,500 mi (4,000 km) long convergent boundary between the North American Plate and the Pacific Plate, that extends from the Alaska Range to the Kamchatka Peninsula. Here, the Pacific Plate is being subducted underneath the North American Plate and the rate of subduction changes from west to east from 7.5 to 5.1 cm per year. The Aleutian subduction zone includes two prominent features, the Aleutian Arc and the Aleutian Trench. The Aleutian Arc was created via volcanic eruptions from dehydration of the subducting slab at ~100 km depth. The Aleutian Trench is a narrow and deep morphology that occurs between the two converging plates as the subducting slab dives beneath the overriding plate.
The Kamchatka-Aleutian triple junction is a triple junction of tectonic plates of the Fault-Fault-Trench type where the Pacific Plate, the Okhotsk Plate, and the North American Plate meet. It is located east of the Kamchatka Mys peninsula and west of Bering Island. Meiji Seamount is located to the southeast of the junction.
On July 17 2017, an earthquake struck near the Komandorski Islands, east of the Kamchatka Peninsula in the Bering Sea at. Although there were no casualties from this earthquake, it was notable for a rare characteristic known as supershear, and is one of the few times a large supershear earthquake has been observed. It was preceded by a few foreshocks months earlier, and aftershocks that continued for nearly six months.