The segment of the Hollister transform between -635 and -650 km (Fig. Cumulative seismic moment release for shocks of Mw > 5.55 from 1976 to 2010 along two segments of Hollister transform fault as indicated in Fig. which two plates create the eltanin fracture zone quizlet The flow of NADW through the Romanche and Chain Fracture Zones may serve as a conduit for larval transport from the western North Atlantic to the eastern South Atlantic. The three sets of large events have a repeat time of 13 yr and a COV of 0.13. Of the 84 earthquakes from 1976 to 1989, we rejected seven CMT solutions. Nine earthquakes from 1969 to 1975 are shown at their body wave locations of the International Seismological Centre (ISC). Earthquakes of Mw > 5.55 were included in each computation. Clearly, a gradient in the maximum size of earthquakes and seismic coupling occurs between the eastern and western ends of the Heezen transform. We obtained a CMT solution for an additional earthquake of Mw 6.15 in 1979. Fig. The San Andreas fault is part of a fault zone known as a transform Earthquakes were not found along nearby fast spreading ridges at that resolution. J.H. The horizontal axis is parallel to computed transform directions; the vertical is perpendicular to it. We have combined shipboard and Seasat altimeter derived data in an intergrated geological and geophysical study of the Louisville Ridge; a 3500kmlong seamount chain extending from the Tonga trench to the Eltanin Fracture Zone. In discriminating the signals of earthquakes from those of underground nuclear explosions low excitation of Rayleigh waves in the narrow period band used for determining Ms may result in a few earthquakes appearing to be explosions. Map view of CMT locations of earthquakes along Tharp transform from 1976 to 2010. Behn 5) are characterized by shocks of Mw= 5.9 but about half of its length is not. The affected zone of the Pacific-Antarctic Ridge is about 800kmlong, 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 (4852.6S 12323.6W). The experiment suggests that when the CMT depth is larger than the true depth, the estimated Mo is too high by a small amount. 7, several of which are aftershocks and foreshocks, are considered to be noise in ascertaining the quasi-periodic behaviour of the larger shocks. Gregg R. They were generally too small to generate stable CMT results. We determined a few CMT mechanisms for which PDE or ISC did not compute hypocentres, for which we relied on detections and locations based on intermediate-period surface waves (Ekstram 2006). Tromp However, a major offset developed on this transform between 60 and 80 Ma, prior to the oldest dated rocks from the ridge. Subsequent locations of earthquakes and mapping of bathymetry and magnetic anomalies showed that the Eltanin zone consisted of three en echelon transforms (Molnar et al. The Antarctic-Pacific Plate boundary, while characterized by somewhat slower rates than segments of the East Pacific Rise farther north, contains three nearby transform faults-the Heezen, Tharp and Hollister-that together are about 1000 km long and have been the sites of numerous earthquakes of moment magnitude, Mw, 5-6.4 during the past 50 years. (1975) obtained strike-slip mechanisms for them and another event in 1967. When Sykes showed his results to M. Ewing, the latter arranged with NSF (US National Science Foundation) for the Research Vessel Eltanin to map the region. The affected zone of the Pacific-Antarctic Ridge is about 800kmlong, 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 (4852.6S 12323.6W). For LNADW and AABW, the Romanche and Chain Fracture Zones (just south of the equator) are the only deep passages in the MAR where interbasin exchange is possible. Seabeam and SeaMARC II swath-mapping surveys, with ancillary magnetic and gravity profiling, describe the fast-slipping (84-86 mm year1) 380 km-long Heezen transform (56 S) and the 145 km-long Raitt transform (54 S), together with the youngest parts of their rise-flank fracture zones. Lamont-Doherty Earth Observatory Contribution 7505. The combined three Eltanin transform faults are much more active at the Mw~ 6 level than a comparable length of either the San Andreas Fault in California or other transform systems on land. Thesaurus Terms | GeoScienceWorld The surface wave catalogue (Ekstram 2006) starts in 1990, and the magnitude that is associated with events in that catalogue is usually very close to the Mw obtained in a CMT analysis. The transverse ridge separates the present trench from an 800km (500mi)-long aseismic valley where the Romanche transform was located until about 108 Ma. The synthetic waveforms used in the CMT inversion are corrected for lateral heterogeneity using the whole-mantle model of Dziewonski & Woodward (1992) for the body waves and long-period mantle waves, and the phase-velocity maps of Ekstrm et al. Fracture Zones : Mendocino Fracture Zone, Murray Fracture Zone, Molokai Fracture Zone, Clarion Fracture Zone, Clipperton Fracture Zone, Challenger Fracture Zone, Eltanin Fracture Zone, Udintsev Fracture Zone Other Pacific Ocean ocean maps Physiography of the Pacific Ocean Countries and islands of the Pacific Region 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. 'dextrally' (also known as right-laterally) which means if you Dotted lines denote approximate locations of ridge segments. Show that the equation is dimensionally correct. The coefficient of variation (COV), the standard deviation, SD, divided by the average repeat time, is 0.26. 8) includes three events that are much larger than the others in that series. According to the normal scenario for the opening of the South Atlantic, it is spreading at a rate of 1.75cm/year (0.69in/year) and began forming about 50 Ma. M.S. . As in Fig. The smaller events in Fig. We did not use the ISC catalogue for events after 1999. S. Carbotte (written communication, 2011 July 22) notes that the concentration of earthquakes at the eastern end of the Heezen transform corresponds with the region where the inside Corner Rift' of Lonsdale (1994) is found to the north. The along strike dimensions and perhaps the downdip widths of asperities must be small for parts of the three Eltanin faults that have not ruptured in events larger than Mw 5.0-5.5. Seismicity and aseismic slip along the Eltanin Fracture Zone 10) was the site of many earthquakes of Mw > 5.55, two of Mw 6.13 and two of Mw 6.0, the latter two on the same day in 2010. Bergman To the north of the Eltanin Fracture Zone, a wider compositional diversity seems to occur, including FeTi-basaltsand trachy andesite, than that observed from within and to the south of this fracture zone and on the Chile Rise. Fielding Nearby ocean bottom seismometers are needed to detect them. Dredged volcanic rocks from the southern oceans: the Eltanin collection Figs 4-6 depict the three Eltanin transforms in greater detail. The random variations can be considered a consequence of the complicated trade-offs that occur when noisy data are fit with synthetic seismograms that do not capture the full complexity of wave propagation in the Earth. - 4:5, using intermediate-period surface waves, Thermal structure of oceanic transform faults, Scaling relations for seismic cycles on mid-ocean ridge transform faults, Aftershock sequences in the mid-ocean ridge environment: an analysis using hydroacoustic data, Determination of earthquake source parameters from waveform data for studies of global and regional seismicity, A very broad band inversion method for the recovery of earthquake source parameters, Global detection and location of seismic sources using surface waves, Measurements and global models of surface wave propagation, Global seismicity of 2003: centroid-moment-tensor solutions for 1087 earthquakes, Source of oceanic magnetic anomalies and geomagnetic polarity time scale, Spreading rate dependence of gravity anomalies along oceanic transform faults, Co-seismic and postseismic slip of the 2004 Parkfield earthquake from space-geodetic data, Structural geomorphology of the Eltanin fault system and adjacent transform faults of the Pacific-Antarctic plate boundary, Seismic cycles and earthquake predictability on east Pacific rise transform faults, Foreshock sequences and short-term earthquake predictability on east Pacific rise transform faults, Magnetic anomalies, bathymetry and the tectonic evolution of the South Pacific since the Late Cretaceous, Three-dimensional flow and temperature perturbations due to a transform offset, Seismic properties of the Eltanin transform system, South Pacific, Global multi-resolution topography synthesis, Multiple, closely spaced transform faults in fast-slipping fracture zones, The effects of temperature and pressure-dependent viscosity on three-dimensional passive flow of the mantle beneath a ridge-transform system, Time-predictable recurrence model for large earthquakes, Seismicity and aseismic slip along the Eltanin fracture zone, Repeat times of large earthquakes: implications for earthquake mechanics and long-term prediction, Moderate and large earthquake activity along oceanic transform faults, Origin of the Louisville ridge and its relationship to the Eltanin fracture zone system, A new class of faults and their bearing on continental drift, Oceanic transform earthquakes with unusual mechanism or locations: relation to fault geometry and state of stress in the adjacent lithosphere, The Authors Geophysical Journal International 2011 RAS, Fault identification and reliability evaluation using an SVM model based on 3D seismic data volume, Surface waves at a fluid/double-porosity medium interface, Adjoint-state traveltime tomography for azimuthally anisotropic media in spherical coordinates, Defining the Yangtze-Cathaysia suture zone in south china using ambient noise tomography, Observations and simulations of the meteotsunami generated by the Tonga eruption on 15 January 2022 in the Mediterranean Sea, Volume 234, Issue 1, July 2023 (In Progress), Volume 233, Issue 3, June 2023 (In Progress), Volume 233, Issue 2, May 2023 (In Progress), Volume 233, Issue 1, April 2023 (In Progress), Geomagnetism, Rock Magnetism and Palaeomagnetism, Marine Geosciences and Applied Geophysics, Appendix B: Trade-off between scalarmoment estimates and depths of CMTS, https://doi.org/10.1111/j.1365-246X.2011.05284.x, Earthquake interaction, forecasting, and prediction, Oceanic transform and fracture zone processes, Receive exclusive offers and updates from Oxford Academic, Copyright 2023 The Royal Astronomical Society. 2. How are fracture zones like the Eltanin created? These are too small to represent the actual uncertainties. We present a compilation of the seismic properties of the Eltanin Transform Fault (TF) system, compelled by the recent discovery of the Hollister Ridge and the possibility of a change of plate. Fracture Zone. Okal & Langenhorst (2000) relocated a number of earthquakes along the three transforms using short-period body waves. The precision of epicentral locations in his study was improved considerably by using data from new seismic stations in Antarctica that were installed during the International Geophysical Year, 1957-1958, and computer programs for analysing P and PKP arrival times. R.C. Their surface wave magnitudes, Ms, are plotted.