Tectonic plate motion

Figure 1.1. Outline index map of the Japanese subduction zones. Thick lines with teeth are converging plate boundaries. Arrows indicate relative plate motions. Abbreviations su, Suruga trough sa, Sagami trough sf, South Fossa Magna triple junction och, Off Central Honshu triple junction ISTL, Itolgawa-Shizuoka Tectonic Line KSM, Kashima VLBl station (Uyeda, 1991).

Wallace, W.K. Engebretson, D.C. 1984. Relationships between plate motions and Late Cretaceous to Paleocene magmatism in southwestern Alaska. Tectonics, 3, 295-315. 

Heat transfer due to the movement of matter from one location to another is called convection. You have probably placed your hand over an open flame of one type or another. Even though there is no physical contact between your hand and the flame, you can still feel the warmth of the flame. Uneven heating is generally the cause of convection in a fluid. For example, the air near an open flame will be heated and become less dense than the air higher above the flame. The heated air will rise while the cooler denser air will fall. The rising warm air will subsequently come into contact with your hand and heat it. Convection also causes the motion of the tectonic plates and air circulation patterns of our planet. 

Closer to home, hydrogen maser clocks have been used to track the motion of the Earth s tectonic plates. Erom tracking stations separated by 209 miles along the San Andreas fault, it was learned that over an eleven-week period, the distance between the two stations increased by eight inches. An earthquake occurred shortly after this determination. There is a likely correlation between this plate motion and the earthquake. The east-west dimension of the United States is more stable. Tracking stations in Massachusetts and California remained a relatively constant 154,680,381 1 inches apart over a five-year period. 

First, the fountains of the great deep were broken up. Whether there were immense amounts of water trapped below the earth s surface that were released, or if a huge upward motion of the ocean floor caused much of the water in the ocean to spill onto the land, we don t know. A recently developed scientific model called Catastrophic Plate Tectonics postulates that intense and violent movement in the tectonic plates resulted in the worldwide disaster of the Flood. 

Compared to tectonic earthquakes at the plate boundaries, the intraplate earthquake swarm areas miss the plate motion that could periodically bring the fault to failure. Recent studies have tried to understand the possible triggering mechanisms by probing/imaging anomalous crustal structures within seismic swarms linked to fluids (e.g., Lin and Shearer 2009 Kato et al. 2010). It is assumed that afluid overpressure builds up and acts as a triggering mechanism of earthquake swarms. The subsequent swarm activity is then probably driven both by the fluid flow along the fault zone and stress transfer from previous earthquakes. This idea is based on characteristic features of earthquake swarms that help us to disclose their background mechanisms. 

The solid plates that resulted from the cooling process at the surface of the eanli were able to float on the remaining molten inner portion of the earth. Because of the rotational motion of the earth about its own axis and the earth s motion in the solar system, inertial and gravitational forces have produced great interactive forces between the plates. It is speculated that these interactive forces have led to plate contact and situations where one plate has slid over another. The great forces created by plate tectonics are likely responsible for the forces that have resulted in the folding and faulting of the earth s crust [30j. 

The energy that powers terrestrial processes is derived primarily from the sun and from the Earth s internal heat production (mostly radioactive decay). Solar energy drives atmospheric motions, ocean circulation (tidal energy is minor), the hydrologic cycle, and photosynthesis. The Earth s internal heat drives convection that is largely manifested at the Earth s surface by the characteristic deformation and volcanism associated with plate tectonics, and by the hotspot volcanism associated with rising plumes of especially hot mantle material. 

The changes in stress fields, and intensities of igneous and hydrothermal activities seem to correlate to oscillatory motion of the Pacific plate (Jackson s episodes) (Jackson et al., 1975 Jackson and Shaw, 1975) (Masuda, 1984). Masuda (1984) and Takeuchi (1987) pointed out that the oscillatory motion of Pacific plate during the least 42 Ma correlates with magmatism, the intensity of tectonism, the change of stress field and the history of sedimentary basin in arc-trench system (Fig. 1.147). The above arguments also suggest that the mineralizations in arc and back-arc systems relate to the oscillatory motion of the Pacific plate. 

Figure 1.147. Jackson s curve and arc stress reorientations. Apparent swing motion of Pacific Plate (Jackson et al., 1975) and regional stress orientation at the Northeast Honshu convergent margin are illustrated in order to show their synchronous relationship. Dashed line represents the average trend of the Hawaiian volcanic chain. Pacific plate moves along the direction with fluctuation in reference to Hawaii Hot Spot. Vertically shaded parts of the graph indicate the climax phases of clockwise episodes . Lower part of the figure shows the phases and reversals in orientation of tectonic stress fields on the inner zone of Northeast Honshu Arc (Takeuchi, 1987).

Many properties and characteristics of the Earth are determined by plate tectonics, according to the theory of which the lithosphere is not a closed shell instead it consists of about a dozen large, rigid plates. These are constantly in motion—on a geological timescale. Each of the plates moves as an independent unit and swims on the softer, but more dense, asthenosphere (Press and Siever, 1995). 

Following burial, marine sediments are recycled via two pathways a crustal route or a mantle route. In the crustal route, burial followed by diagenesis, catagenesis, and metagenesis transfers sediments into either sedimentary or metamorphic rocks. These rocks are eventually uplifted onto land by crustal motions associated with plate tectonics. In the mantle recycling route, sediments and sedimentary rocks are subducted at... 

Tectonism Earthquake, volcanic, and other crustal motions associated with the process of plate tectonics. 

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