Cascadia

Cascadia, a term that derives from the Cascade Range, may refer to:

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Cascadia subduction zone

Coordinates: 45°N 124°W / 45°N 124°W / 45; -124 The Cascadia subduction zone (also referred to as the Cascadia fault) is a convergent plate boundary that stretches from northern Vancouver Island to northern California. It is a very long sloping subduction zone fault that separates the Juan de Fuca and North America plates.

The denser oceanic plate is subducting beneath the less dense continental plate offshore of British Columbia, Washington, Oregon and northern California. The North American Plate moves in a general southwest direction, overriding the oceanic plate. The Cascadia Subduction Zone is where the two plates meet.

Tectonic processes active in the Cascadia subduction zone region include accretion, subduction, deep earthquakes, and active volcanism of the Cascades. This volcanism has included such notable eruptions as Mount Mazama (Crater Lake) about 7,500 years ago, Mount Meager about 2,350 years ago, and Mount St. Helens in 1980. Major cities affected by a disturbance in this subduction zone would include Vancouver and Victoria, British Columbia; Seattle, Washington; and Portland, Oregon.

Subduction

In geology, subduction is the process that takes place at convergent boundaries by which one tectonic plate moves under another tectonic plate and sinks into the mantle as the plates converge. Regions where this process occurs are known as subduction zones. Rates of subduction are typically centimetres per year, with the average rate of convergence being approximately two to eight centimetres per year.

Plates include both oceanic crust and continental crust. Stable subduction zones involve the oceanic lithosphere of one plate sliding beneath the continental lithosphere or oceanic lithosphere of another plate due to the higher density of the oceanic lithosphere. That is, the subducted lithosphere is always oceanic while the over-riding lithosphere may or may not be oceanic. Subduction zones are sites that have a high rate of volcanism, earthquakes, and mountain building.

Orogenesis, or mountain-building, occurs when large pieces of material on the subducting plate (such as island arcs) are pressed into the over-riding plate or when subhorizontal contraction occurs in the over-riding plate. These areas are subject to many earthquakes, which are caused by the interactions between the subducting slab and the mantle, the volcanoes, and (when applicable) the mountain-building related to island arc collisions.

Juan de Fuca

Ioánnis Phokás (Greek: Ιωάννης Φωκάς), better known by the Spanish transcription of his name, Juan de Fuca (born 1536 on the Ionian island of Cefalonia; died there 1602), was a Greek maritime pilot in the service of the King of Spain, Philip II. He is best known for his claim to have explored the Strait of Anián, now known as the Strait of Juan de Fuca, between Vancouver Island (now part of British Columbia, Canada) and the Olympic Peninsula (northwestern Washington State, United States).

Family and early life

Phokás's grandfather, Emmanouíl Phokás (Gr: Εμμανουήλ Φωκάς), fled Constantinople at its fall in 1453, accompanied by his brother Andrónikos (Gr: Ανδρόνικος). The two settled first in the Peloponnese, where Andrónikos remained, but in 1470 Emmanouíl moved to the island of Cefalonia. Iákovos (Gr: Ιάκωβος), Ioánnis's father established himself in the village of Valerianos (Gr: Βαλεριάνος) on the island and came to be known as "the Valeriáno Fokás" (Gr: ο Φωκάς ο Βαλεριάνος) to distinguish him from his brothers.

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