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# Poles oce 661 oce 661 oce 661 h flat earth plate

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Unformatted text preview: changes Poles. Poles. OCE 661 OCE 661 OCE 661 h Flat Earth Plate Geometry Simple vector addition can be used to approximate motion of plates on a sphere for a local area. Spherical trig solutions are needed for global solutions. OCE 661 The east African Rift is The part of a RRR triple junction junction OCE 661 The motion of a plate can be described by a The rotation about a virtual axis which passes through the center of the sphere (Euler's Theorem). In terms of the Earth this implies that motions of plates on a sphere can be described by an angular velocity vector originating at the center of the globe. velocity The most widespread parameterization of such a vector is using latitude, longitude, describing the location where the rotation axis cuts the surface of the Earth, and a rotation rate that corresponds to the magnitude of the angular velocity (degrees per m.y. or microradians per year). The latitude and longitude of the angular velocity vector are called the “Euler Euler pole”. pole Because angular velocities behave as vectors, the Because motion of a plate can be expressed as a rotation w= w k, where w is the angular velocity, k is a unit vector along the rotation axis, w the rotation rate. The motion of individual plates can be described by an absolute motion angular velocity. The motion angular The between two plates, which have different absolute motion poles, can be expressed by an angular velocity of relative motion. Plate tectonic theory was velocity developed by determining relative motion between developed plates, which - in general - is easier to measure than their absolute motions. their OCE 661 ω= angular velocity, also called Euler vector angular Euler ω = rotation rate at point on sphere, measured in radians/year (rad/yr) (rad/yr) r = vector pointing to a position on sphere. The magnitude of this vector corresponds to the radius of the sphere, measured in meters (m). meters v = linear velocity vector at r v = speed at r, measured in millimeter...
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