TheTehuantepec Ridge (Tehuantepec Fracture Zone, Tehuntepec Ridge)[2] is a linearundersea ridge located off the west coast of Mexico in the Pacific Ocean. It is the remnant of an oldfracture zone, and not atectonic spreading center ridge (seemid-ocean ridge). It extends from the eastern end of theClipperton fracture zone northeastward toward Mexico intoChiapas andEl Chichón[3] until it is subducted into theMiddle America Trench. It lies within the tectonicCocos plate, separating the lower and older seafloor of the Guatemala Basin which lies southeast of the ridge from higher and younger seafloor which lies to its north-west.
Current research indicates that the ridge was formed as afracture zone andtransform fault along theEast Pacific Rise. As a result of a change in the motion of thePacific plate about 13 million years ago, there was also a change in the orientation of the East Pacific Rise, which in turn reoriented the fracture zone, creating the current alignment that is today's Clipperton Fracture Zone. The Tehuantepec Ridge preserves the previous orientation. To its north the O’Gorman Fracture Zone has a similar orientation.
Some researchers have hypothesized that the subducted portion of the Tehuantepec Ridge under Mexico is responsible for the existence ofEl Chichón volcano as well as the other volcanoes of what is called the Chiapanecan Volcanic Arc. Studies of the 1982 eruption of El Chichón indicated its erupted output was unusual compared to other volcanoes in theTrans-Mexican Volcanic Belt which lies well to the northwest. The anomaly is thought to result from the distinctive composition of the rocks which comprise the Tehuantepec Ridge.[4][5]
12°21′40.8″N97°46′21.5″W / 12.361333°N 97.772639°W /12.361333; -97.772639[2]
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