Azores–Gibraltar transform fault: Difference between revisions
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The '''Azores–Gibraltar Transform Fault''' ('''AGFZ'''), also called a [[fault (geology)|fault zone]] and a [[fracture zone]], is a major seismic fault in the Central [[Atlantic Ocean]] west of the [[Strait of Gibraltar]]. |
The '''Azores–Gibraltar Transform Fault''' ('''AGFZ'''), also called a [[fault (geology)|fault zone]] and a [[fracture zone]], is a major seismic fault in the Central [[Atlantic Ocean]] west of the [[Strait of Gibraltar]]. It is the product of the complex interaction between the [[African Plate|African]], [[Eurasian Plate|Eurasian]], and [[Iberian Plate|Iberian]] plates.<ref name="Rich-etal">{{Harvnb|Richardson|Musson|Horsburgh|2006|loc=Appendix A, Tectonics of the Azores-Gibraltar fault zone, pp. 94–97}}</ref> |
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Forming the Atlantic segment of the boundary between the |
Forming the Atlantic segment of the boundary between the African and Eurasian plates, the AGFZ is largely dominated by compressional forces between these converging (3.8–5.6 mm/yr) plates, but it is subject of a dynamic tectonic regime also involving extension, transcurrent, and compression. The [[oceanic crust|oceanic]] [[lithosphere]] in the area is one of the oldest preserved on Earth directly related to the [[opening of the North Atlantic Ocean]].<ref name="MartLori-intro">{{Harvnb|Martínez‐Loriente|Sallarès|Gràcia|Bartolome|2014|loc=Introduction, p. 127}}</ref> |
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It runs eastward from the eastern end of the [[Terceira Rift]] in the [[Azores]] and extends east through the Strait of Gibraltar and into the [[Mediterranean Sea]]. The section east of Gibraltar is poorly understood and is currently regarded as a "diffuse" boundary. Many geologists believe the fault connects with a [[subduction zone]] where the African Plate is slowly subducting beneath the Eurasian Plate somewhere in the vicinity of the [[Italian Peninsula]]. |
It runs eastward from the eastern end of the [[Terceira Rift]] in the [[Azores]] and extends east through the Strait of Gibraltar and into the [[Mediterranean Sea]]. The section east of Gibraltar is poorly understood and is currently regarded as a "diffuse" boundary. Many geologists believe the fault connects with a [[subduction zone]] where the African Plate is slowly subducting beneath the Eurasian Plate somewhere in the vicinity of the [[Italian Peninsula]].<ref name="Rich-etal" /> |
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The western end of the AGFZ, the [[Azores Triple Junction]] on the [[Mid-Atlantic Ridge]] (MAR), is where the North American, African, and Eurasian plates meet. Spreading in the MAR is faster south of the AGFZ than north of it, which results in a [[transform fault|trancurrent]] movement along the AGFZ at about {{convert|4|mm/yr|abbr=on}}.<ref name="Rich-etal" /> |
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The fault is described as a right-lateral [[transform fault]], moving about {{convert|4|mm|in|abbr=on}} per year, but eastern segments of the fault show evidence of compression as well. |
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The eastern segment of the fault is complex and characterised by a series of seamounts and ridges separating the [[Tores Abyssal Plain|Tores]] and [[Horseshoe Abyssal Plain|Horseshoe]] abyssal plains. The active compressional deformation in this segment is an extremely rare example of compression between two oceanic litospheres.<ref name="Rich-etal" /> |
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The AGFZ produced the large-magnitude [[1755 Lisbon earthquake|1755 Lisbon]] and [[1969 Portugal earthquake|1969 Horseshoe]] earthquakes and, consequently, a number of tsunamis.<ref name="MartLori-intro" /> |
The AGFZ produced the large-magnitude [[1755 Lisbon earthquake|1755 Lisbon]] and [[1969 Portugal earthquake|1969 Horseshoe]] earthquakes and, consequently, a number of tsunamis.<ref name="MartLori-intro" /> |
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Revision as of 11:15, 29 October 2016
The Azores–Gibraltar Transform Fault (AGFZ), also called a fault zone and a fracture zone, is a major seismic fault in the Central Atlantic Ocean west of the Strait of Gibraltar. It is the product of the complex interaction between the African, Eurasian, and Iberian plates.[1]
Forming the Atlantic segment of the boundary between the African and Eurasian plates, the AGFZ is largely dominated by compressional forces between these converging (3.8–5.6 mm/yr) plates, but it is subject of a dynamic tectonic regime also involving extension, transcurrent, and compression. The oceanic lithosphere in the area is one of the oldest preserved on Earth directly related to the opening of the North Atlantic Ocean.[2]
It runs eastward from the eastern end of the Terceira Rift in the Azores and extends east through the Strait of Gibraltar and into the Mediterranean Sea. The section east of Gibraltar is poorly understood and is currently regarded as a "diffuse" boundary. Many geologists believe the fault connects with a subduction zone where the African Plate is slowly subducting beneath the Eurasian Plate somewhere in the vicinity of the Italian Peninsula.[1]
The western end of the AGFZ, the Azores Triple Junction on the Mid-Atlantic Ridge (MAR), is where the North American, African, and Eurasian plates meet. Spreading in the MAR is faster south of the AGFZ than north of it, which results in a trancurrent movement along the AGFZ at about 4 mm/a (0.0050 in/Ms).[1] The eastern segment of the fault is complex and characterised by a series of seamounts and ridges separating the Tores and Horseshoe abyssal plains. The active compressional deformation in this segment is an extremely rare example of compression between two oceanic litospheres.[1]
The AGFZ produced the large-magnitude 1755 Lisbon and 1969 Horseshoe earthquakes and, consequently, a number of tsunamis.[2]
References
- ^ a b c d Richardson, Musson & Horsburgh 2006, Appendix A, Tectonics of the Azores-Gibraltar fault zone, pp. 94–97
- ^ a b Martínez‐Loriente et al. 2014, Introduction, p. 127
Sources
- Martínez‐Loriente, S.; Sallarès, V.; Gràcia, E.; Bartolome, R.; Dañobeitia, J. J.; Zitellini, N. (2014). "Seismic and gravity constraints on the nature of the basement in the Africa‐Eurasia plate boundary: New insights for the geodynamic evolution of the SW Iberian margin" (PDF). Journal of Geophysical Research: Solid Earth. 119 (1): 127–149. doi:10.1002/2013JB010476. Retrieved 29 October 2016.
{{cite journal}}: Invalid|ref=harv(help) - Richardson, S.; Musson, R.; Horsburgh, K. (2006). Tsunamis–Assessing the hazard for the UK and Irish coast (PDF (7.8Mb)). 41st Defra Flood and Coastal Management Conference. York, UK. Retrieved 29 October 2016.
{{cite conference}}: Invalid|ref=harv(help)
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