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The North American Plate is a tectonic plate covering most of North America, Cuba, the Bahamas, extreme northeastern Asia, and parts of Iceland and the Azores. With an area of 76 million km2 (29 million sq mi), it is the Earth's second largest tectonic plate, behind the Pacific Plate.
The Rivera Triple Junction (RTJ) is a geologic triple junction located on the seafloor of the Pacific Ocean southeast of the southern tip of the Baja California Peninsula. At the RTJ, three tectonic plates intersect: the North American Plate, the Rivera Plate, and the Pacific Plate. The triple junction is often referenced as the southern counterpart of the Mendocino Triple Junction, but it is not as well understood. One research effort describes it as an R-R-R (ridge-ridge-ridge) type junction which lies along the segment of the East Pacific Rise which runs between the Rivera Transform Fault and the Tamayo Fault, although the third axis of the junction is not clearly defined. Part of the problem in describing the Rivera Triple Junction is that if it were truly analogous to the Mendocino Triple Junction, then it would exist at the junction of the East Pacific Rise, the Tamayo Fault, and the Middle America Trench. But thus far, there does not appear to be any evidence that the Tamayo Fault or the East Pacific Rise intersect the Middle America Trench at all, thus presenting a possible example of a diffuse triple junction.
The Rivera Transform Fault, also referred to as the Rivera Fracture Zone, is a right lateral-moving (dextral) transform fault which lies along the seafloor of the Pacific Ocean off the west coast of Mexico just south of the mouth of the Gulf of California. It runs between two segments of the East Pacific Rise, forming the southwest boundary of the small Rivera Plate. The fault is broken into two segments, bisected by a short rifting zone.
The Imperial Fault Zone is a system of geological faults located in Imperial County in the Southern California region, and adjacent Baja California state in Mexico. It cuts across the border between the United States and Mexico.
The Cerro Prieto Fault is a transform fault located in far northern Baja California. It runs between the Cerro Prieto spreading center located southwest of Mexicali, and the Wagner Basin, another spreading center which lies under the Gulf of California. These spreading centers are part of the East Pacific Rise, the northern leg of which has formed the Gulf of California by steadily rifting the Baja California Peninsula away from the mainland of Mexico.
The Delfin Basin is a pair of interconnected submarine depressions located on the seabed of the northern Gulf of California. The northernmost of these is called the Upper Delfin Basin while the southernmost is called the Lower Delfin Basin. Both of these features are areas of subsidence caused by extensional forces imparted by a spreading center associated with the East Pacific Rise. The two basins are linked by a short transform fault which was the apparent source of an earthquake of magnitude 5.5 on November 26, 1997.
The Consag Basin is a submarine depression in the far northern part of the Gulf of California associated with the East Pacific Rise. It lies south of the Wagner Basin with which it is closely linked. The depression is a result of subsidence caused by the extensional forces probably imparted by the same spreading center which has produced the Wagner Basin. Both basins are bounded on their eastern side by the Wagner Fault, a primarily normal fault which dips approximately 60 degrees to the northwest. The western side of the basin is bounded by another normal fault, the Consag Fault which dips in a direction opposite the Wagner Fault. The seabed between these faults is sinking.
The Ballenas Fault is a transform fault located on the seabed of the Gulf of California, extending through the Canal de Ballenas which separates the Isla Ángel de la Guarda from the Baja California Peninsula. The fault is an integral part of the East Pacific Rise, linking the Delfin Basin in the north with a smaller spreading center to the south. The fault is considered the northernmost member of a grouping of four transform faults called the Guaymas Transform Fault System.
The Guaymas Fault, named for the city of Guaymas, Sonora, Mexico, is a major right lateral-moving transform fault which runs along the seabed of the Gulf of California. It is an integral part of the Gulf of California Rift Zone, the northern extremity of the East Pacific Rise. The Guaymas Fault runs from the San Pedro Martir Basin located at the southern end of the San Lorenzo Fault, and extends southward to the Guaymas Basin, a heavily sedimented rift which includes both continental and oceanic crust and contains numerous hydrothermal vents.
The Gulf of California Rift Zone (GCRZ) is the northernmost extension of the East Pacific Rise which extends some 1,300 km (800 mi) from the mouth of the Gulf of California to the southern terminus of the San Andreas Fault at the Salton Sink.
The Alarcon Basin is a submarine depression located on the seabed at the southern end of the Gulf of California. The basin results from the activity of the southernmost spreading center in the Gulf. This spreading center has also produced the southernmost oceanic rift in the Gulf of California Rift Zone, the Alarcon Rise. The basin and rise are linked to the Tamayo Fault to the south, and the Pescadero Fault in the north.
The Carmen Fault is a right lateral-moving transform fault located on the seafloor of the southern Gulf of California. It links the Guaymas Basin to the north with the Carmen Basin to the south. All these features are part of the Gulf of California Rift Zone, the northern extension of the East Pacific Rise.
The Farallon Fault is a right lateral-moving transform fault located on the seafloor of the southern Gulf of California. It links the Carmen Basin to the north with the Farallon Basin to the south. All these features are part of the Gulf of California Rift Zone, the northern extension of the East Pacific Rise.
The Pescadero Fault is a right lateral-moving transform fault located on the seafloor of the southern Gulf of California. It links the Pescadero Basin to the north with the Alarcon Basin to the south. All these features are part of the Gulf of California Rift Zone, the northern extension of the East Pacific Rise.
The Atl Fault is a right lateral-moving transform fault located on the seafloor of the southern Gulf of California. It links the Farallon Basin to the north with the Pescadero Basin to the south. All these features are part of the Gulf of California Rift Zone, the northern extension of the East Pacific Rise.
The Salton Trough is an active tectonic pull-apart basin, or graben. It lies within the Imperial, Riverside, and San Diego counties of southeastern California and extends south of the Mexico–United States border into the state of Baja California.
The 1892 Laguna Salada earthquake occurred at 23:20 Pacific Standard Time on February 23. It had an estimated moment magnitude of 7.1–7.2 and a maximum perceived intensity of VIII (Severe). The shock was centered near the Mexico–United States border and takes its name from a large dry lake bed in Baja California, Mexico. There were no reported casualties, but the event affected the then largely-uninhabited areas of northern Mexico and Southern California.
The San Quintín Volcanic Field is a collection of ten or eleven volcanic cinder cones situated along the Pacific coast of the Baja California peninsula in Mexico. The field formed by repeated eruptions beginning in the Pleistocene and ending about 3000 years ago. It is one of several known Quaternary period volcanic fields in Baja. The lava shields appear to have first grown as subaqueous volcanoes that emerged as islands.
References
- The Tamayo transform fault in the mouth of the Gulf of California, Kastens et al (1979)
- Tectonics at the Intersection of the East Pacific Rise with Tamayo Transform Fault, Gallo et al (1983)
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