Dotted lines denote approximate locations of ridges. His relocations along the Heezen transform, with one exception, are more tightly clustered than ours. Search for: Recent Posts. Sunrise, sunset, day length and solar time for Stockholm County. Test the following series for convergence or divergence. L.R. J.J. 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. J.K. T2=42r3/(GM), m3/(kgs2)m ^ { 3 } / \left( k g \cdot s ^ { 2 } \right) Who is Jason crabb mother and where is she? 4. Nearby asperities, as along the eastern part of the Heezen transform, may break either individually or together. D.F. The data for Mw > 5.9 are fit remarkably well by the slip predictable model of Shimazaki & Nakata (1980) whereby the size of the next earthquake is proportional to the time since the previous event. Table S1 in the Supporting Information lists the formal uncertainties of the revised centroid locations. . Gee 3 and studied separately. From the scatter of locations perpendicular to the Eltanin transforms, the standard deviation of locations would be around 15 km, after allowing for a constant regional bias. [8], Coordinates: .mw-parser-output .geo-default,.mw-parser-output .geo-dms,.mw-parser-output .geo-dec{display:inline}.mw-parser-output .geo-nondefault,.mw-parser-output .geo-multi-punct{display:none}.mw-parser-output .longitude,.mw-parser-output .latitude{white-space:nowrap}000N 1800W / 0.000N 18.000W / 0.000; -18.000, "Dolomite formation in pelagic limestone and diatomite, Romanche Fracture Zone, Equatorial Atlantic", 10.1175/1520-0485(1998)028<1929:MITRFZ>2.0.CO;2, "Lower Cretaceous to Eocene sedimentary transverse ridge at the Romanche Fracture Zone and the opening of the equatorial Atlantic", "Hydrothermal activity on the southern Mid-Atlantic Ridge: Tectonically- and volcanically-controlled venting at 45S", "Transport of Bottom Water in the Romanche Fracture Zone and the Chain Fracture Zone", 10.1175/1520-0485(1998)028<0779:TOBWIT>2.0.CO;2, "Biodiversity and biogeography of hydrothermal vent species: thirty years of discovery and investigations", https://en.wikipedia.org/w/index.php?title=Romanche_Trench&oldid=1090955796, This page was last edited on 1 June 2022, at 10:32. The two dotted lines in Fig. Figs 5 and 6 show five other normal-faulting mechanisms adjacent to but not on the Tharp and Hollister transforms. Figs 4-6 depict the three Eltanin transforms in greater detail. The transverse ridge separates the present trench from an 800km (500mi)-long aseismic valley where the Romanche transform was located until about 108 Ma. Those P waves left hypocentres close to the intersection of the two nodal planes (B-axis) where their amplitude is very small. It is therefore unlikely that the event selection for 19902009 missed any earthquake with a moment magnitude greater than 5.5. An up-to-date map of the Antarctic Circumpolar Current (ACC) fronts is constructed from the latest version of mean dynamic topography from satellite altimetry (Park et al., 2019, Observations of the Antarctic Circumpolar Current over the Udintsev Fracture Zone, the narrowest choke point in the . 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. S. Carbotte (written communication, 2011 July 22) notes, however, that some of the shocks along the eastern end of the Tharp transform might fall within a zone of deformed/rotated seafloor south of the transform that looks quite similar to the zone of deformation north of the Heezen transform described by Lonsdale (1994) and seen in Fig. This yielded 84 earthquakes. 1). 2. Abercrombie Cumulative seismic moment release for shocks of Mw > 5.55 from 1969 to 2010 along three additional segments of Heezen transform fault as indicated in Fig. 4 and red symbols in Fig. Phipps Morgan & Forsyth (1988), Shen & Forsyth (1992), Behn (2007), Gregg et al. Palaeoseismically determined dates for earthquakes along faults of the San Andreas system are uncertain, whereas exact dates are known for the events we examine along the Eltanin transforms. This is a consequence of the continuity of displacement eigenfunctions for surface waves across discontinuities, and the dependence of the excitation on these displacements. That segment may well not be a single isolated an asperity as that in Fig. J.J. 7, many of the smaller events are either aftershocks or foreshocks and are considered to be noise for the purposes of assessing the repeat times of the largest earthquakes. The 'Ar-39Ar dating of rocks dredged either side of the break suggest that it is analogous to the bend in the Hawaiian-Emperor seamount chain. Pacific Ocean depth map showing the Heezen Fault and the Tharp Fault as #17. NASA Technical Reports Server (NTRS) Kyte, Frank T.; Gersonde, Rainer; Kuhn, Gerhard. 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.The affected zone of the Pacific-Antarctic Ridge is about 800 km long, between 56 S, 145 W and 54.5 S, 118.5 W, southwest of Easter Island, and about as far as one can get from . . . 3391km (2107mi) WSW of Ushuaia, Argentina Unfortunately, the computed depths of earthquakes along the three Eltanin transforms are not accurate enough to ascertain centroid depths or the downdip width of seismic faulting at the several to 20 km level. The transform valley is 15-20 km wide and 2-4 km deep. This is an improvement over past formulations where bathymetric offsets were imposed kinematica. 1997, 2005). Hirth 3) to indicate stationarity of well-coupled and poorly coupled behaviour along transform segments since at least 1969. 2. Distances along the transform are calculated from an arbitrary origin of coordinates at 55.4 S, 125.0 W. Seamount chains in the Pacific basin tend to be aligned northwesterly, and several chains are intimately associated with fracture zones; the Eltanin Fracture Zone in the southwestern Pacific is an example. Moment magnitudes are given below each solution. Stewart Eltanin fracture zone fracture zone zone of fracture n. , rock fracture zone Mendocino fracture zone oceanic fracture zone deep fracture zone Charlie Gibbs fracture zone - oceanic floor fracture zone S. Carbotte kindly computed the bathymetric map in Fig. Experience has shown that deviations of the CMT centroid depth from the true depth occur both randomly and systematically. Some of our largest events occur within about 25 km of the eastern end of the Heezen and the western end of the Hollister transforms (Figs 4 and 6). [4] No thrust earthquake mechanisms, however, were found along the Tharp zone. [3], Series of faults that offset the Pacific-Antarctic Ridge. These are too small to represent the actual uncertainties. They found that all depths were less than 20 and a few better determined solutions were shallower than 5 km below the seafloor. R.C. J.S. In detailed swath mapping of three ultra fast-moving transforms just to the south of the equator, Searle (1983) found that each consisted of two or more short transforms bounded by very short spreading centres. Ekstram At 14.5W the trough reaches a maximum depth of 2895 fm (5470 m). Enter your email address to follow this blog and receive notifications of new posts by email. Our distributions of earthquakes do not fit other thermal models that we have examined. stand on one side of it, the other side appears to move to the 7, however, since it is located just to the east of other large shocks along the Heezen transform. Excluding it does not change the average repeat time for events of Mw > 5.9; it increases the SD and COV slightly. Unlike all the other countries in the St. Cecilia Archipelago, Eltanin is only comprised of one island. 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.The affected zone of the Pacific-Antarctic Ridge is about 800 km long, between 56 S, 145 W and 54.5 S, 118.5 W, southwest of Easter Island, and about as far as one can get from . Eltanin Fracture Zone on the Elevation Map. T.H. What is the answer punchline algebra 15.1 why dose a chicken coop have only two doors? Oxford University Press is a department of the University of Oxford. He concluded that a major fracture zone intersected the mid-oceanic ridge at that location, much like those mapped by Menard (1960) farther north. R.L. The sense of the rotation is such that one or more offsets between parts of the Tharp transform would be short compressional features rather than spreading centres. Rolandone In addition those three oceanic transforms are not as multibranched as many transform zones on continents. Series of faults that offset the Pacific-Antarctic Ridge, "Seismicity and Aseismic Slip Along the Eltanin Fracture Zone", "The Pacififi c-Antarctic Ridge between 4115'S and 5245'S: Survey and sampling during the PACANTARCTIC 2 cruise", "Earthquakes along Eltanin transform system, SE Pacific Ocean: fault segments characterized by strong and poor seismic coupling and implications for long-term earthquake prediction", https://en.wikipedia.org/w/index.php?title=Eltanin_Fault_System&oldid=1068451688, Creative Commons Attribution-ShareAlike License 3.0, This page was last edited on 28 January 2022, at 13:46. He attributed this to changes in the Euler pole for Pacific-Nasca plate motion during the last several million years. They find that aftershock zones of nearby pairs of moderate-size earthquakes along fast-moving transforms were separated by small spreading centres. Earthquakes were not found along nearby fast spreading ridges at that resolution. Our results indicate considerable variation in moment release and hence in fault coupling along the strike of the three Eltanin transforms. 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. They differ in that hypocentres derived using body waves give the location of rupture initiation whereas CMT solutions give centroid locations and origin times. E. W. F. We did not use the ISC catalogue for events after 1999. Dziewonski [7] The trench has been formed by the actions of the Romanche Fracture Zone, a portion of which is an active transform boundary offsetting sections of the Mid-Atlantic Ridge. Our locations and those of the ISC based on body waves are located systematically about 25 km south of the transforms as mapped in Fig. "zone" in Chinese : n. 1. () 2. 3. . We assume that earthquakes along a given segment of a transform occur on single faults although the distribution of CMT solutions scatters about 15 km perpendicular to the transforms. Recurrence of events along nearly the same fault segment is much more difficult to determine for transform faults on land, such as the San Andreas, where large to great earthquakes typically have repeat times of 100 yr or longer and instrumental data and exact dates for more than one earthquake along a fault segment are rare or non-existent. D.R. Exploring Data Coaching Activity: Longshore C, SmartFigure: Geostrophic current and western. Burgmann - 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. VanDeMark R. Behn 2). Although Forsyth L.R. The centroid epicentre and time did not shift appreciably in these different inversions, nor did the geometry of the moment tensor change appreciably. The most recent data show, for example, that the Eltanin fracture zone system in the South Pacific is much longer than previously thought, according to Marsh. It is one the the major earthquake zones in . 4 occurred. Wilson (1965) utilized the observation that earthquakes along the Eltanin fracture zone were confined to the zone between two offset ridge crests in formulating his hypothesis of transform faulting. Behn The slope of -1.0 for the latter period for Mw 5.4-6.0 is typical of that for earthquakes in many areas of the world. Eltanin fracture zone Scope Notes: SE Pacific. They represent a good laboratory for examining fault segments that slip aseismically, others that are well coupled, and the short recurrence times of earthquakes. GE was partially supported by NSF grant EAR-09-24694. Their surface wave magnitudes, Ms, are plotted. What is the reflection of the story of princess urduja? Wolfe Lynn R. Sykes, Gran Ekstrm, 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, Volume 188, Issue 2, February 2012, Pages 421434, https://doi.org/10.1111/j.1365-246X.2011.05284.x. Fig. Mw determined in this study compared with the surface wave magnitude Ms as computed by either ISC or PDE for periods between about 17 and 22 s. Mw is determined at longer periods. Ryan In contrast, normal-faulting events of Mw 5-6.5 are common along slower spreading ridges such as those in the Atlantic. Shimazaki The relationship between the two events that occurred on the same day with computed CMTs only 5 km apart is unknown. 6). Lamont-Doherty Earth Observatory Contribution 7505. 1975; Lonsdale 1994), which were named for M. Tharp, B. Heezen and C. Hollister . west coast of the USA through California. What kind of fault is represented by the eltanin and romanche fracture zones? A.M. Most of the earlier earthquakes analysed here are larger than Mw= 5.5, since smaller earthquakes appear to have gone largely undetected until the 1990s. Instead, we have chosen not to use models of the depth of seismic faulting in estimating coupling but to calculate downdip width from a segments length along strike, moment release rate and relative plate rate assuming' full seismic coupling. Where is and what is Eltanin Transform Fault and Fracture Zone? The normal-faulting event of 2001 August 6 is larger than that of any of the strike-slip events along the three Eltanin transforms. The absence of known earthquakes on the three transforms beyond their bounding ridge crests and the spacing of magnetic anomalies, however, indicate that the Pacific and Antarctic plates are intact today beyond the active parts of those transforms and that the lengths of the transforms are not continuing to grow. There are about 300 fracture zones, with an average north-south separation of 55 kilometres (34 mi): two for each degree of latitude. We then examine other segments with fewer but larger earthquakes. We propose that the remainder of the plate motion . T. right. T. Tolstoy Watts Since that segment is adjacent to the one in blue in Fig. M. Hence, remote techniques such as seismicity and satellite altimetry provide important constraints on the tectonics, especially for the Tharp and Hollister transforms. The average repeat time for the eight events of Mw > 5.9 is 4.0 1.0 (1 SD) yr. and the Eurasian plate. Montesi Symbols, axes and origin of coordinates same as Fig. G. Broader Terms: East Pacific Pacific Ocean South Pacific Southeast Pacific 4706 km S of Papeete, French Polynesia / pop: 26,400 / local time: 01:42:15.1 2017-06-15 Okal & Langenhorst (2000) relocated a number of earthquakes along the three transforms using short-period body waves. 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. The existence of three or four plates in the region during those times permitted offset to grow across the Eltanin system (Watts et al. Nine earthquakes from 1969 to 1975 are shown at their body wave locations of the International Seismological Centre (ISC). [1] The two major faults in the Eltanin Fracture Zone are the Heezen Fault and the Tharp Fault. Stewart & Okal (1983) concluded that earthquakes along the Eltanin zone from 1920 to 1981 accounted for less than 10 per cent of the slip predicted by kinematic models of plate motion and cooling. Indeed, jets are observed to pass along both the Udinstev and Eltanin Fracture Zones (Gille 1994; Hughes and Ash 2001). Solomon The North Anatolian Fault is formed along the Anatolian plate Events in 2010 were determined in the same manner and are listed in the catalogue of the GCMT project at http://www.globalcmt.org. . 4. Which letter is pointing to a transform fault? where is and what is eltanin transform fault and fracture. These segments contain fewer events of Mw > 5.9 than that in Fig. Chou Lonsdale (1994) states My interpretation is that mechanical coupling across the transform valley allows eastward drag by the old thick Antarctic lithosphere to impede the westward movement away from the rise crest of a 20-30-km-wide adjacent strip of thin, newly accreted Pacific lithosphere'. We also analysed the P waves of the two largest normal-faulting events, those of 2001 and 2007 (Fig. S1 in the Supporting Information). The transform valley is 15-20 km wide and 2-4 km deep. Cumulative seismic moment release from 1976 to 2010 along a 42-km section of Heezen transform indicated in Fig. Woodward In detail the distribution of fault segments is likely to be fractal. "fault" or "fault line". If the anomalous trend is real, having one group of events (east or west) off the primary transform then almost becomes a necessary interpretation. If the 1981 shock were mislocated at least 12 km eastwards, the length of the repeating segment would be about 30 km. Farther west activity decreases to a maximum of Mw 5.9-6.1 between +30 and +100 km along the fault and then again to a maximum of Mw 5.6-5.8 between +10 and 30 km. 7 includes an earthquake on 1981 June 20 of Mw 5.94, which was located just to the east of the others at a time when relatively few stations were available for calculating a CMT location. This translates into a lack of sensitivity of the CMT algorithm in the estimation of the centroid depth, and instances in which the centroid depth differs appreciably from the true depth of the earthquake, here considered the centre of seismic moment. As in Fig. How do you say Eltanin Fracture Zone? The segment of the Tharp transform between -210 and -241 km has a T of 8 yr, Mw 6.08-6.3 and five events. Lin S.C. The catalogue for the latter period appears to be complete for Mw > 5.4-5.5 whereas the earlier period is not complete for Mw < 6.0. Sunrise: 06:37AM; Sunset: 05:22PM; Day length: 10h 45m; The local time in Stockholm County is currently the same as the solar time. He found that interevent times for those pairs was tightly clustered around 5 yr with a COV ~ 0.2. The mechanism in the GCMT catalogue indicates normal faulting, while the reanalysis resulted in a strike-slip mechanism. Nevertheless, modelling body waves is difficult for strike-slip earthquakes along the Eltanin transforms because their amplitudes are small at recording stations that necessarily are at very large distances. The linearity of the CMT locations along the shorter Hollister transform (Fig. One exception to this general observation is the earthquake on 2000 October 4. 4. These species await a formal description and it is not known whether or not they represent communities distinct from those on the northern MAR. of fracture zones in the southern oceans by mavis lynn driscoll b.a., university of california at berkeley, 1981 submitted in partial fulfillment of the requirements for the degree of doctor of philosophy at the massachusetts institute of technology and the woods hole oceanographic institution june 1987 Menke McGuire (2008) also found that 1-d aftershock zones extended 30-50 km along strike for Mw~ 6 main shocks for transforms of the East Pacific Rise near the equator. 3). The steep slope of about -2.9 for Mw > 6 is unusual. The relatively small size of that earthquake, its early date and the off-transform locations of other normal-faulting events lead us conclude it more likely occurred just north of the Heezen transform. 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. 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. 4699 km SW of Santiago, Chile / pop: 4,837,295 / local time: 15:09:44.3 2016-08-18 which two plates create the eltanin fracture zone quizlet; Well Inspection using ROV at Kondashetti Halli, Bangalore How that may vary along strike and affect seismic coupling is unknown. (1993) and Lonsdale (1994) describe three short spreading centres with a total length of about 6 km along the seismically quiet part of the Heezen transform between 125.5 and 126 W (Fig. 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.The affected zone of the Pacific-Antarctic Ridge is about 800 km long, between 56 S, 145 W and 54.5 S, 118.5 W, southwest of Easter Island, and about as far as one can get from . 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. Elevation map for localities Click for legend, zoom in for elevation lines Routing error m , | Map style: OpenTopoMap ( CC-BY-SA) J. 4279 km S of Papeete, French Polynesia / pop: 26,357 / local time: 16:34:59.2 2016-05-02, Distances: 1977km (1228mi) N of Siple, Mount, Antarctica The greater number of stations in the last 20 years permitted CMT solutions to be obtained for a large number of smaller earthquakes, some as small as Mw 5.15. Thermal models with constant and variable mineral physics properties are formally analyzed for fits against recently filtered databases for heat flow and topography. A break in the smooth trend of the ridge at latitude 37.5S has been recognized in both bathymetric and altimetric data. 4. Ms, which is typically reported by PDE and ISC only for Rayleigh waves and for periods between about 18 and 22 s, may yield a biased estimate of the long-period character of a seismic source as a result of low excitation at certain focal depths and biased sampling of the radiation field. C1. The San Andreas Fault zone of western North America. Wolfe et al. Marathon Expedition, Leg 6 Studies in the Tonga Trench, Louisville Ridge, and Eltanin Fracture Zone The average of the three intervals since 1967 is 12.8 yr with a COV of 0.36. The solutions, additional methodology and other pertinent data are described more fully in Appendix A and the Supporting Information. Since the 40-km section of the Tharp (Fig. 2. However, a major offset developed on this transform between 60 and 80 Ma, prior to the oldest dated rocks from the ridge. Four segments of the Tharp transform (Fig. The seismic history of the Eltanin Fracture Zone on the Pacific-Antarctic Ridge for the years 1920-81 shows that the seismic slip accumulated during this recording interval accounts for only a small fraction (<10%) of the amount of slip predicted by kinematic models of plate motion. As AABW flows through the Romanche Fracture Zone, salinity and temperature increase significantly. 7 is not unreasonable for single events of Mw 5.9-6.1. They may be regarded as quasi-periodic. 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 three sets of large events have a repeat time of 13 yr and a COV of 0.13. Wolfe et al. Only the Heezen transform has been surveyed by swath mapping (Lonsdale 1994). 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. Given the uncertainty of its CMT location, we think it is reasonably associated with a previous rupture of the same asperity as in Figs 4 and 7. . D.V. We find that seismic coupling is not merely a function of relative plate velocity, location along the transform and transform length. . Numbers for 15 yr period 1976-1990 were multiplied by 20/15. Thus, the use of the CMT methodology insured more complete coverage of earthquakes in this very remote area of the Earth. Ekstram This completeness can be seen as well by the slope of 1.0 of the LogNMw relationship in Fig. Cumulative moment release along that segment is displayed in Fig. A new analysis of plate cooling models indicates that the properties of oceanic lithosphere may need to be reevaluated, or that additional phenomena beyond the conditions of simple mineral physics plate models are important. The axes are each rotated with respect to the Euler rotation pole of DeMets et al. [1], Lower North Atlantic Deep Water (LNADW) is found around 3,6004,000 metres (11,80013,100ft) below sea level and flows from the Greenland and Norwegian seas; it brings high salinity, oxygen, and freon concentrations towards the equator. Distances: 4585 km SE of Wellington, New Zealand / pop: 382,000 / local time: 23:42:15.1 2017-06-15 fault zone where the two blocks/plates on either side move side by Other short spreading centres may exist along the Tharp and other parts of the Heezen transforms. The smallest is likely to be an underestimate, since several patches within what we take to be the seismically active part of the Hollister transform were not active at the Mw= 5.9 level. Solid line indicates Mw=Ms. At faster separating parts of the Pacific-Antarctic boundary, and on most of the rest of the EPR, fracture zone structure is mainly inherited from the variable arrangement of volcanic ridges and tectonic uplifts at the risecrest intersections, rather than from structures formed at the transform valley.