Related Research Articles
Cascadia and Cascadian are terms that derive from the Cascade Range and may refer to:
The Juan de Fuca plate is a small tectonic plate (microplate) generated from the Juan de Fuca Ridge that is subducting beneath the northerly portion of the western side of the North American plate at the Cascadia subduction zone. It is named after the explorer of the same name. One of the smallest of Earth's tectonic plates, the Juan de Fuca plate is a remnant part of the once-vast Farallon plate, which is now largely subducted underneath the North American plate.
A turbidite is the geologic deposit of a turbidity current, which is a type of amalgamation of fluidal and sediment gravity flow responsible for distributing vast amounts of clastic sediment into the deep ocean.
The Cascadia subduction zone is a 960 km (600 mi) fault at a convergent plate boundary, about 100–200 km (70–100 mi) off the Pacific coast, that stretches from northern Vancouver Island in Canada to Northern California in the United States. It is capable of producing 9.0+ magnitude earthquakes and tsunamis that could reach 30 m (98 ft). The Oregon Department of Emergency Management estimates shaking would last 5–7 minutes along the coast, with strength and intensity decreasing further from the epicenter. It is a very long, sloping subduction zone where the Explorer, Juan de Fuca, and Gorda plates move to the east and slide below the much larger mostly continental North American plate. The zone varies in width and lies offshore beginning near Cape Mendocino, Northern California, passing through Oregon and Washington, and terminating at about Vancouver Island in British Columbia.
The Hikurangi Trough is a sea floor feature of the Pacific Ocean off the north-east South Island and the east coast of the North Island of New Zealand. It has been forming for about 25 million years and is turbidite-filled, particularly in its south. This characteristic can be used to distinguish it from the sediment-poor and deeper Kermadec Trench, which is its continuation to the north. Sediment currently passing through the trough represents about 0.5% of the total sediment input to the world oceans. The trough has deep-sea chemosynthetic ecosystems that are unique.
A submarine canyon is a steep-sided valley cut into the seabed of the continental slope, sometimes extending well onto the continental shelf, having nearly vertical walls, and occasionally having canyon wall heights of up to 5 km (3 mi), from canyon floor to canyon rim, as with the Great Bahama Canyon. Just as above-sea-level canyons serve as channels for the flow of water across land, submarine canyons serve as channels for the flow of turbidity currents across the seafloor. Turbidity currents are flows of dense, sediment laden waters that are supplied by rivers, or generated on the seabed by storms, submarine landslides, earthquakes, and other soil disturbances. Turbidity currents travel down slope at great speed, eroding the continental slope and finally depositing sediment onto the abyssal plain, where the particles settle out.
A turbidity current is most typically an underwater current of usually rapidly moving, sediment-laden water moving down a slope; although current research (2018) indicates that water-saturated sediment may be the primary actor in the process. Turbidity currents can also occur in other fluids besides water.
Abyssal fans, also known as deep-sea fans, underwater deltas, and submarine fans, are underwater geological structures associated with large-scale sediment deposition and formed by turbidity currents. They can be thought of as an underwater version of alluvial fans and can vary dramatically in size, with widths from several kilometres to several thousands of kilometres. The largest is the Bengal Fan, followed by the Indus Fan, but major fans are also found at the outlet of the Amazon, Congo, Mississippi and elsewhere.
The Blanco Fracture Zone or Blanco Transform Fault Zone (BTFZ) is a right lateral transform fault zone, which runs northwest off the coast of Oregon in the Pacific Northwest of the United States, extending from the Gorda Ridge in the south to the Juan de Fuca Ridge in the north.
The geology of the Pacific Northwest includes the composition, structure, physical properties and the processes that shape the Pacific Northwest region of North America. The region is part of the Ring of Fire: the subduction of the Pacific and Farallon Plates under the North American Plate is responsible for many of the area's scenic features as well as some of its hazards, such as volcanoes, earthquakes, and landslides.
Abyssal channels are channels in Earth's sea floor. They are formed by fast-flowing floods of turbid water caused by avalanches near the channel's head, with the sediment carried by the water causing a build-up of the surrounding abyssal plains. Submarine channels and the turbidite systems which form them are responsible for the accumulation of most sandstone deposits found on continental slopes and have proven to be one of the most common types of hydrocarbon reservoirs found in these regions.
A contourite is a sedimentary deposit commonly formed on continental rises in lower slope settings, although it may occur anywhere that is below the storm wave base. Countourites are produced by thermohaline-induced deepwater bottom currents and may be influenced by wind or tidal forces. The geomorphology of contourite deposits is mainly influenced by the deepwater bottom-current velocity, sediment supply, and seafloor topography.
The Northwest Atlantic Mid-Ocean Channel (NAMOC) is the main body of a turbidity current system of channels and canyons running on the sea bottom from the Hudson Strait, through the Labrador Sea, and ending at the Sohm Abyssal Plain in the Atlantic Ocean. Contrary to most other such systems which fan away from the main channel, numerous tributaries run into the NAMOC and end there. The density of those tributaries is the highest near the Labrador Peninsula, but the longest tributary, called Imarssuak Mid-Ocean Channel (IMOC), originates in the Atlantic Ocean.
Ocean Networks Canada is a world-leading research and ocean observing facility hosted and owned by the University of Victoria, and managed by the not-for profit ONC Society. ONC operates unparalleled observatories in the deep ocean and coastal waters of Canada’s three coasts–the Arctic, the Pacific and the Atlantic–gathering biological, chemical, geological and physical data to drive solutions for science, industry and society. ONC operates the NEPTUNE and VENUS cabled ocean observatories in the northeast Pacific Ocean and the Salish Sea. Additionally, Ocean Networks Canada operates smaller community-based observatories offshore from Cambridge Bay, Nunavut., Campbell River, Kitamaat Village and Digby Island. These observatories collect data on physical, chemical, biological, and geological aspects of the ocean over long time periods. As with other ocean observatories such as ESONET, Ocean Observatories Initiative, MACHO and DONET, scientific instruments connected to Ocean Networks Canada are operated remotely and provide continuous streams of freely available data to researchers and the public. Over 200 gigabytes of data are collected every day.
Congo Canyon is a submarine canyon found at the end of the Congo River in Africa. It is one of the largest submarine canyons in the world.
The Quinault Canyon is a submarine canyon, off Washington state, in Olympic Coast National Marine Sanctuary.
The Astoria Fan is a submarine fan. It has sediment, radiating asymmetrically southward from the mouth of the Astoria Canyon. From Astoria Canyon's mouth, the fan extends about 100 kilometres (62 mi) to its western end, which is the Cascadia Channel. The fan proper ends 160 kilometres (99 mi) south of the canyon mouth, although its depositional basin extends southward another 150 kilometres (93 mi) to the Blanco Fracture Zone.
Quileute Canyon is a submarine canyon, off of Washington state, United States.
Juan de Fuca Channel is a submarine channel off the shore of Washington state, United States and the Strait of Juan de Fuca.
The Kaikōura Canyon is a geologically active submarine canyon located southwest of the Kaikōura Peninsula off the northeastern coast of the South Island of New Zealand. It is 60 kilometres (37 mi) long, and is generally U-shaped. The canyon descends into deep water and merges into an ocean channel system that can be traced for hundreds of kilometres across the deep ocean floor. At the head of the Kaikōura Canyon, the depth of water is around 30 metres (98 ft), but it drops rapidly to 600 metres (2,000 ft) and continues down to around 2,000 metres (6,600 ft) deep where it meets the Hikurangi Channel. Sperm whales can be seen close to the coast south of Goose Bay, because the deep water of the Kaikōura Canyon is only one kilometre (0.62 mi) off the shoreline in this area.
References
- 1 2 Gary Bruce Griggs. "Cascadia Channel: The Anatomy of a Deep-Sea Channel" (PDF). Retrieved 4 September 2017.
- 1 2 3 4 Brian F. Atwater and Gary B. Griggs (2012). "Deep-Sea Turbidites as Guides to Holocene Earthquake History at the Cascadia Subduction Zone— Alternative Views for a Seismic-Hazard Workshop" (PDF). United States Geological Survey. Retrieved 11 September 2017.
- ↑ Gary B. Griggs (September 20, 1973). "Origin and Development of Cascadia Deep-Sea Channel". Journal of Geophysical Research . 78 (27): 6325–6339. Bibcode:1973JGR....78.6325G. doi:10.1029/JC078i027p06325.
- ↑ G.B.Griggs, A.G.CareyJr., L.D.Kulm (April 1969). "Deep-sea sedimentation and sediment-fauna interaction in Cascadia Channel and on Cascadia Abyssal Plain". Deep Sea Research and Oceanographic Abstracts. 16 (2): 157–166. Bibcode:1969DSRA...16..157G. doi:10.1016/0011-7471(69)90071-0.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ↑ "Turbidite evidence". Pacific Northwest Seismic Reference. Retrieved 14 September 2017.