Eltanin Fault System Explained

The Eltanin Fault System (Eltanin Fracture Zone) is a series of six or seven dextral transform faults that offset the Pacific-Antarctic Ridge, a spreading zone between the Pacific Plate and the Antarctic Plate. This is extending by up to 7.93cm/year. It was named after the oceanographic ship USNS Eltanin.

Description

The affected zone of the Pacific-Antarctic Ridge is about 800km (500miles) long, between 56° S, 145° W and 54.5° S, 118.5° W,^[1] southwest of Easter Island, and about as far as one can get from land on planet Earth (48°52.6′S 123°23.6′W).^[2] However, the total offset is about 1600 km. The two major faults in the Eltanin Fracture Zone are the Heezen transform fault and the Tharp transform fault, usually known as fracture zones as they extend inactively from the Pacific-Antarctic Ridge. A third named after Hollister, which is the shortest to the south, also exists and its active transform region has been linked to the other transform regions of the Eltanin Fault System. They are about 1000km (1,000miles) long and have been in the last 50 years the location of many earthquakes of up to . One segment of the Heezen transform has ruptured with an average repeat interval of 4 years. Others related faults include the Vacquier Transform Fault, the Menard Transform Fault, and the Udintsev Fault.^[3]

To the northwest, in an almost linear fashion as seafloor features, are the Hollister Ridge and the Louisville Seamount Chain.

See also

• Hollister Ridge

Sources

• Sykes . Lynn R. . Ekstörm . Göran. 2011. Earthquakes along Eltanin transform system, SE Pacific Ocean: fault segments characterized by strong and poor seismic coupling and implications for long-term earthquake prediction. Geophysical Journal International. 188. 2. 421 - 434. 10.1111/j.1365-246X.2011.05284.x. 2012GeoJI.188..421S . free.

Further reading

• Beutel, Erin K. . Okal, Emile A.. 2003. Strength asperities along oceanic transform faults: a model for the origin of extensional earthquakes on the Eltanin transform system. Earth and Planetary Science Letters. 216. 1/2. 27 - 41. 10.1016/S0012-821X(03)00484-9. 2003E&PSL.216...27B .
• Kashintsev, G.L. . Frikh-khar, D.. 1978. Structure of the oceanic crust in the Eltanin Fault Zone (Pacific Ocean) based on petrographic data. Oceanology. 18. 39 - 42.
• Lonsdale, Peter. 1986. Tectonic and magmatic ridges in the eltanin fault system, South Pacific. Marine Geophysical Researches. 8. 3. 203 - 242. 10.1007/BF00305484. 1986MarGR...8..203L .
• Lonsdale, Peter. 1994. Structural geomorphology of the Eltanin fault system and adjacent transform faults of the Pacific-Antarctic plate boundary. Marine Geophysical Researches. 16. 2. 105 - 143. 10.1007/BF01224756. 1994MarGR..16..105L .
• Okal, Emile A. . Langenhorst, Amy R.. 2000. Seismic properties of the Eltanin Transform System, South Pacific. Physics of the Earth and Planetary Interiors. 119. (3/4. 185 - 208. 10.1016/S0031-9201(99)00169-7. 2000PEPI..119..185O .
• Stewart, Lisa M. . Okal, Emile A.. 1983. Seismicity and Aseismic Slip Along the Eltanin Fracture Zone. Journal of Geophysical Research. 88. B12. 10,495 - 10,507. 10.1029/jb088ib12p10495. 1983JGR....8810495S .

Notes and References

1. Lonsdale, Peter. 1994. Structural geomorphology of the Eltanin fault system and adjacent transform faults of the Pacific-Antarctic plate boundary. Marine Geophysical Researches. 16. 2. 105 - 143. 10.1007/BF01224756. 1994MarGR..16..105L .
2. Because of the generally remote character of the epicentral area (the Eltanin Fracture Zone is indeed close to the point at sea farthest away from any land shore) page 10.497, Stewart, Lisa M. . Okal, Emile A.. 1983. Seismicity and Aseismic Slip Along the Eltanin Fracture Zone. Journal of Geophysical Research. 88. B12. 10,495 - 10,507. 10.1029/jb088ib12p10495. 1983JGR....8810495S .
3. Dosso, L.. 2005. The Pacififi c-Antarctic Ridge between 41°15'S and 52°45'S: Survey and sampling during the PACANTARCTIC 2 cruise. InterRidge News. 14. 1 - 4. etal.