Cascadia Subduction Zone

Information about Cascadia Subduction Zone

Structure of the Cascadia subduction zone

Area of the Cascadia subduction zone

The Cascadia subduction zone is a very long sloping fault that stretches from northern Vancouver Island to northern California.

Geography

The zone separates the Juan de Fuca, Explorer, Gorda and the North American Plate. Here, the oceanic crust of the Pacific Ocean is pushed toward and beneath the continent at a rate of 40 mm/yr.

The width of the Cascadia subduction zone fault varies along its length, depending on the temperature of the subducted oceanic plate, which heats up as it is pushed deeper beneath the continent. As it becomes hotter and more molten, it eventually loses the ability to store mechanical stress and generates earthquakes.

Earthquakes

Because of the very large fault area, the Cascadia subduction zone can produce very large earthquakes, magnitude 9.0 or greater, if rupture occurred over its whole area. When the "locked" zone stores up energy for an earthquake, the "transition" zone, although somewhat plastic, can rupture. Thermal and deformation studies indicate that the locked zone is fully locked for 60 kilometers (about 40 miles) downdip from the deformation front. Further downdip, there is a transition from fully locked to aseismic sliding. (Nedimovic, et al., 2003)

In 1999, a group of Continuous Global Positioning System sites registered a brief reversal of motion of approximately 2 centimeters (0.8 inches) over a 50 kilometer by 300 kilometer (about 30 mile by 200 mile) area. The movement was the equivalent of a 6.7 magnitude earthquake. (Dragert, et al., 2001) The motion did not trigger an earthquake and was only detectable as silent, non-earthquake seismic signatures. (Rogers & Dragert, 2003)

The last known great earthquake in the northwest was in January of 1700, the Cascadia Earthquake. Geological evidence indicates that great earthquakes may have occurred at least seven times in the last 3,500 years, suggesting a return time of 300 to 600 years. There is also evidence of accompanying tsunamis with every earthquake, and one line of evidence for these earthquakes is tsunami damage, and through Japanese records of tsunamis.

A future rupture of the Cascadia Subduction Zone would cause widespread destruction throughout the Pacific Northwest.

Other similar subduction zones in the world usually have such earthquakes every 100–200 years; the longer interval here may indicate unusually large stress buildup and subsequent unusually large earthquake slip.

Volcanoes

The volcanoes within the subduction zone include:

References

Atwater, BF (1987). "Evidence for great Holocene earthquakes along the outer coast of Washington State". Science 236 (4804): 942-44.
Nedimovic MR, Hyndman RD, Ramachandran K, Spence GD (2003). "Reflection signature of seismic and aseismic slip on the northern Cascadia subduction interface". Nature 424 (6947): 416-20. PMID 12879067.
Dragert G, Wang K, James TS (2001). "A silent slip event on the deeper Cascadia subduction interface". Science 292 (5521): 1525-8. PMID 11313500.
Rogers G, Dragert H (2003). "Episodic tremor and slip on the Cascadia subduction zone: the chatter of silent slip". Science 300 (5627): 1942-3. PMID 12738870.

External links

Giant Earthquakes Beneath Canada's West Coast. Geological Survey of Canada - Pacific Division. Retrieved on 2006-06-10.

fault or fault line is a planar rock fracture, which shows evidence of relative movement. Large faults within the Earth's crust are the result of shear motion and active fault zones are the causal locations of most earthquakes.
..... Click the link for more information.

..... Click the link for more information.

Editing of this page by unregistered or newly registered users is currently disabled due to vandalism.
If you are prevented from editing this page, and you wish to make a change, please discuss changes on the talk page, request unprotection, log in, or .
..... Click the link for more information.

The Juan de Fuca Plate, named after the explorer, is a tectonic plate arising from the Juan de Fuca Ridge, and subducting under the northerly portion of the western side of the North American Plate.
..... Click the link for more information.

The Explorer Plate is an oceanic tectonic plate beneath the Pacific Ocean off the west coast of Vancouver Island, Canada.

To the east, the Explorer Plate is being subducted under the North American Plate.
..... Click the link for more information.

The Gorda Plate, located beneath the Pacific Ocean off the coast of northern California, is one of the northern remnants of the Farallon Plate. It is sometimes referred to (by, for example, publications from the USGS Earthquake Hazards Program [1] ) as simply the
..... Click the link for more information.

North American Plate is a tectonic plate covering most of North America, extending eastward to the Mid-Atlantic Ridge and westward to the Cherskiy Range in East Siberia.
..... Click the link for more information.

Oceanic crust is the part of Earth's lithosphere that surfaces in the ocean basins. Oceanic crust is primarily composed of mafic rocks, or sima. It is thinner than continental crust, or sial, generally less than 10 kilometers thick, however it is more dense, having a mean density
..... Click the link for more information.

Earth's oceans
(World Ocean)

Arctic Ocean
Atlantic Ocean
Indian Ocean
Pacific Ocean
Southern Ocean

The Pacific Ocean (from the Latin name Mare Pacificum
..... Click the link for more information.

1 millimetre =
SI units
010⁻³ m 0 cm
US customary / Imperial units
010⁻³ ft 010⁻³ in

The millimetre (American spelling: millimeter, symbol mm
..... Click the link for more information.

A year (from Old English gēr) is the time between two recurrences of an event related to the orbit of the Earth around the Sun. By extension, this can be applied to any planet: for example, a "Martian year" is the time in which Mars completes its own orbit.
..... Click the link for more information.

In geology, aseismic creep is measurable surface displacement along a fault in the absence of notable earthquakes.

An example is along the Calaveras fault in Hollister, California.
..... Click the link for more information.

Global Positioning System (GPS) is the only fully functional Global Navigation Satellite System (GNSS). Utilizing a constellation of at least 24 medium Earth orbit satellites that transmit precise microwave signals, the system enables a GPS receiver to determine its
..... Click the link for more information.

16th century - 17th century - 18th century
1670s 1680s 1690s - 1700s - 1710s 1720s 1730s
1697 1698 1699 - 1700 - 1701 1702 1703

:
Subjects: Archaeology - Architecture -
..... Click the link for more information.

1700 Cascadia Earthquake was a magnitude 8.7 – 9.2 megathrust earthquake that occurred in the Cascadia subduction zone in 1700. The earthquake involved the Juan de Fuca Plate underlying the Pacific ocean, from mid-Vancouver Island in southwest Canada off British Columbia to
..... Click the link for more information.

Oceanic crust 0-20 Ma
..... Click the link for more information.

tsunami (IPA: /(t)sʊˈnɑːmi/) is a series of waves created when a body of water, such as an ocean, is rapidly displaced.
..... Click the link for more information.

Pacific Northwest, abbreviated PNW, or PacNW is a region in the northwest of North America. There are several partially overlapping definitions but the term Pacific Northwest should not be confused with the Northwest Territory (aka the Great Northwest) or the
..... Click the link for more information.

Mount Silverthrone (officially gazetted as Silverthrone Mountain) is a circular 20 km (12 mi) wide, deeply dissected caldera complex in Regional District of Mount Waddington, British Columbia, in the Pacific
..... Click the link for more information.

Mount Meager (sometimes mistakenly spelled Meagre or Meagher) is a potentially active complex volcano in the Pacific Ranges of the Coast Mountains of British Columbia, Canada, above the west flank of the Lillooet River and just south of the Lillooet Icecap.
..... Click the link for more information.

Mount Cayley is an eroded stratovolcano in southwestern British Columbia, Canada. It is located 11 km (7 mi) southwest of Callaghan Lake and 24 km (15 mi)
..... Click the link for more information.

Mount Garibaldi is a dormant stratovolcano in the southernmost Coast Mountains of British Columbia. This heavily eroded dome complex is located within Garibaldi Provincial Park overlooking the town of Squamish, about 65 kilometres (40 mi) north of Vancouver.
..... Click the link for more information.

Mount Baker (elevation 10,778 feet, 3,285 m) is a glaciated andesitic stratovolcano in the Cascade Volcanic Arc and the Cascades of Washington State in the United States about 30 mi (48 km)
..... Click the link for more information.

Glacier Peak (known in the Sauk Indian dialect of Lushootseed as "Tda-ko-buh-ba" or "Takobia" ^[2]) is the most remote of the five major volcanoes in the Cascade Volcanic Belt in Washington.
..... Click the link for more information.

Mount Rainier is an active^[1] stratovolcano in Pierce County, Washington, located 54 miles (87 km) southeast of Seattle, Washington, in the United States.
..... Click the link for more information.

For the mountain in California, see .

Mount St. Helens is an active stratovolcano in Skamania County, Washington, in the Pacific Northwest region of the United States.
..... Click the link for more information.

Mount Adams may refer to any of four mountains in the United States and one in New Zealand:

Mount Adams (Colorado), near the Crestones of the Sangre de Cristo Range
Mount Adams (New Hampshire), in the White Mountains
Mount Adams (Washington)

..... Click the link for more information.

Mount Hood (called Wy'east by the Multnomah tribe), is a stratovolcano in the Cascade Volcanic Arc in northern Oregon, in the Pacific Northwest region of the United States.
..... Click the link for more information.

Mount Jefferson is a common name for mountains in the United States, usually referring to Thomas Jefferson, the country's third president. The mountains include:

Name State County Coordinates USGS 7.
..... Click the link for more information.

This article is copied from an article on Wikipedia.org - the free encyclopedia created and edited by online user community. The text was not checked or edited by anyone on our staff. Although the vast majority of the wikipedia encyclopedia articles provide accurate and timely information please do not assume the accuracy of any particular article. This article is distributed under the terms of GNU Free Documentation License.

Herod_Archelaus

iPedia Free Information Center