5 contains only two earthquakes of Mw 5.45 and 5.50. Mw is systematically higher than mb for strike-slip events along the three transforms, on average about 0.5 units. A single strike-slip event of Mw 5.15 was obtained along a long section of the western part of the Heezen transform between -110 and +10 km. Distances in kilometres same as in Fig. The 30- to 42-km length that we used for the repeating events along the Heezen transform in Fig. Their poorly determined repeat times range from 13 to 24 yr. 1975; Lonsdale 1994), which were named for M. Tharp, B. Heezen and C. Hollister (Fig. A.M.
Excluding it does not change the average repeat time for events of Mw > 5.9; it increases the SD and COV slightly. Correct Option: O They are the scars on the seafloor basalt that are created by offsets in the mid-ocean ridge. 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. Others related faults include the Vacquier Transform Fault, the Menard Transform Fault, and the Udintsev Fault. It bisects the Mid-Atlantic Ridge (MAR) just north of the equator at the narrowest part of the Atlantic between Brazil and West Africa, extending from 2N to 2S and from 16W to 20W. J.J.
This includes the HGLP, SRO and ASRO networks in the 1970s, the SRO, ASRO, DWWSSN, CDSN and Geoscope networks for the 1980s, and the IRIS/USGS GSN, Geoscope, GEOFON and MedNet networks since the 1990s. and the Eurasian plate. A Seabeam reconnaissance of the 400 km-long fast-slipping (88 mm yr-1) Heezen transform fault zone and the 55 km-long spreading center that links it to Tharp transform defined and bathymetrically described several types of ridges built by tectonic uplift and volcanic construction. Those P waves left hypocentres close to the intersection of the two nodal planes (B-axis) where their amplitude is very small. The Atlantis Fracture Zone (30 N) is one of the smallest transform faults along the Mid-Atlantic Ridge with a spatial offset of 70 km and an age offset of ~ 6 Ma. You can help Wikipedia by expanding it. 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. 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. Numbers for 15 yr period 1976-1990 were multiplied by 20/15. The time intervals again are well fit by the slip predictable model (dotted red line). 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'. Dziak
Ekstram
The Romanche and Chain Fracture Zones creates a huge gap in the MAR and can act as a "Subsea Berlin Wall" segregating the North Atlantic communities from those in other oceans. 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 Plateand the Antarctic Plate. Dziewonski
stand on one side of it, the other side appears to move to the F.
The Udintsev Fracture Zone is a suitable site for a long-term monitoring of the Antarctic Circumpolar Current 1 Introduction The Antarctic Circumpolar Current (ACC) forms a continuous near-zonal band of eastward flow. M.S. This technique has the potential to rigorously assess hotspot fixity and to locate extinct hotspots. Events of Mw > 5.9 account for 70 per cent of the moment in Fig. For the eight fault segments examined in Figs 7-10 some systematic behaviour can be seen among Mws of the largest earthquakes, their average repeat times, T, and the numbers of large events. . "zone of fracture" in Chinese : , ; ; ,; ; "amsterdam fracture zone" in Chinese : "aseismic fracture zone" in Chinese : P.
Our calculations of moment magnitude Mw are compared with determinations of the short-period magnitude mb in Fig. Log of cumulative number of earthquakes per 20 yr larger than a given Mw as a function of Mw. His events along what we identify as a well-coupled zone between 29 and 59 km in Fig. Bergman
Gee
FRACTURE ZONE. It is that region where three of the four normal faulting earthquakes in Fig. Richards, W.B.F. 2). 4. D.F. 6) indicates that it may be a single fault. Which letter is pointing to a transform fault? . Which letter(s) is/are pointing to an inactive fracture zone? 4. 4). Nearby ocean bottom seismometers are needed to detect them. Swarms of hydrothermal shrimps reminiscent of those found from northern MAR vent-sites have been found on the northern part of the southern MAR. Map view of CMT locations of earthquakes along Hollister transform fault from 1976 to 2010. S.C.
T.F. 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. 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. If the 1981 shock were mislocated at least 12 km eastwards, the length of the repeating segment would be about 30 km. Their surface wave magnitudes, Ms, are plotted. [3], The Romanche Fracture Zone offsets the Mid-Atlantic ridge by 900km (560mi), making it the largest equatorial fracture zone in the Atlantic. It seems unlikely that our CMT location errors would change much over the length of the Tharp transform. We show in detail, however, that some segments of the three transforms are aseismic at the Mw > 5.4 level whereas others are more strongly coupled. Menke
Bar at upper right on map shows water depths in metres. Burgmann
Major differences in seismic coupling along strike are not in accord with common thermal models of plate cooling but instead are attributed to varying degrees of metamorphism, rock type and effective normal stress and possibly to the presence of short intratransform spreading centres. 1 for events of Mw 6.2 in 1983 and 2007. The CMT centroid depths for events along the Eltanin system are not accurate enough to define the depths or range of seismic faulting at the level of several to 20 km. The remaining five segments were the sites of fewer large shocks of Mw 6.0-6.39. D.V. 2006-01-01. If so, their repeat time was about 16 yr but is based on only three events. Explanation: Fracture zones are characterised as structural line View the full answer Transcribed image text: How are fracture zones like the Eltanin created? The steep slope of about -2.9 for Mw > 6 is unusual. . . Fig. 4), to constrain their source depths. Dziewonski
Atwater
A.R. 7) has the shortest T, 4.0 yr, Mw 5.93-6.07 and eight events. We conclude that strike-slip and normal faulting along the three Eltanin transforms are partitioned so that strike-slip faulting takes place along the transforms themselves and normal faulting occurs nearby but just off the transforms. What is the reflection of the story of princess urduja?
We used a box from 54S to 58S and 140W to 120W to identify earthquakes that might be located on the Eltanin transform system. W.
Arvidsson
Symbols, axes and origin of coordinates same as Fig. They conclude that the Blanco and Gofar transforms, which were the target of their study, appear to be comprised of multiple patches on a single fault segment that repeatedly fail in earthquakes that rupture each of those patches. The continuity in smooth trend of the ridge and the Eltanin Fracture Zone suggests some relationship between them. S. Carbotte kindly computed the bathymetric map in Fig. Ekstram
Thus, the use of the CMT methodology insured more complete coverage of earthquakes in this very remote area of the Earth. 1975; Lonsdale 1994), which were named for M. Tharp, B. Heezen and C. Hollister . Their length, relative simplicity, 80 mm yr-1, long-term slip rate and the lack of known shocks of Mw > 7 make them a good laboratory for studying quasi-periodic recurrence of earthquakes on a timescale of years to a few decades. . florida a jurassic transform plate boundary. The centroid epicentre and time did not shift appreciably in these different inversions, nor did the geometry of the moment tensor change appreciably. Thermal models with constant and variable mineral physics properties are formally analyzed for fits against recently filtered databases for heat flow and topography. 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. Boettcher
a) reproduction b) controlling an experiment c) growth and development d) maintaining a steady temperature, An equation for the period T of a planet (the time to make one orbit about the Sun) is, T2=42r3/(GM)T ^ { 2 } = 4 \pi ^ { 2 } r ^ { 3 } / ( G M ) The excitation of the long-period waveforms used in the CMT analysis does not vary rapidly as a function of source depth for shallow-focus earthquakes. Ryan and M. Tolstoy for helpful discussions. 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. Four of them have T-axes nearly perpendicular to those transforms while the smallest of Mw 5.3 in 1982 is oriented about 45 to the Tharp.
We did not use the ISC catalogue for events after 1999.
SEANOE. CHALLENGER FRACTURE ZONE. 3457km (2148mi) S of Adamstown, Pitcairn. The ridge segments and transform faults of the East Pacific Rise and Pacific-Antarctic ridge are the sites of the fastest rates of the seafloor spreading and relative plate motion in the world. If you are interested in visiting one of these Fracture Zone(s) in Undersea Features always contact the local Office of Natural Resources to gather all the regulations for fishing and outdoor adventures in the area. The centroids of events of larger Mw are found at least 35 km eastwards along the Heezen transform and those to its west are relatively small. Two 20-km segments of the Hollister transform (Figs 3 and 6) are the sites of several earthquakes of Mw= 5.9 whereas only single shocks of that size are found along its western half. Hence, with its inclusion, the series appears to be complete from at least 1981 to 2010. In that simple model, earthquakes should extend to greater depths and presumably be larger near the centres of transforms, which is clearly not the case for the Heezen and Tharp faults. Forsyth
In addition those three oceanic transforms are not as multibranched as many transform zones on continents. Earthquakes of Mw 6.2-6.4 occur along each transform but larger events are confined to the eastern half of the Heezen, two parts of the Tharp and segments of the Hollister. J.J.
The average of the three intervals since 1967 is 12.8 yr with a COV of 0.36. 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 . 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 Phipps Morgan & Forsyth (1988), Shen & Forsyth (1992), Behn (2007), Gregg et al. Moment release over 35 yr per unit length along strike for each of those segments is 3.5 0.7 1014 N m m-1. He found that interevent times for those pairs was tightly clustered around 5 yr with a COV ~ 0.2. . 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 . transform plate boundaries learning geology. We find or confirm two anomalous characteristics: the . Note exaggerated scale in transform-perpendicular direction. Gordon
7; several were the sites of two or three earthquakes of Mw > 6.15.
. How are fracture zones like the Eltanin created? Hence, a variety of rupture behaviours, repeat times and maximum observed magnitudes is associated with the active parts of the three transforms.
C2 shows that Mw is similar to Ms at larger magnitudes but is 0.40.9 units larger at Mw 5.4. . The presence of large events just to its west and the variety of Mws, however, suggest that it does not always rupture as a single asperity. Woodward
The continuity in smooth trend of the ridge and the Eltanin Fracture Zone suggests some relationship between them. We note that our revised catalogue with its additions of more solutions, especially of Mw 5.5-6.0, is more complete than the existing CMT catalogue. J.
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. We find that seismic coupling is not merely a function of relative plate velocity, location along the transform and transform length. They obtained a depth in the range 8-14 km below the seafloor for the 1978 earthquake off the Heezen fault, and approximately 10 km below the seafloor for the 1989 earthquake off the Tharp transform. This experiment addresses one component of the potential bias that may be present in CMT seismic moments. It moves Eltanin Fracture Zone System: IHO-IOC GEBCO Gazetteer of Undersea Feature Names : English: Eltanin Fracture Zone: US BGN Advisory Committee on Undersea Features (ACUF) PlaceType: Fracture Zone : Latitude: 54 8' 16.8" S (-54.137999) Longitude: 127 32' 7.3" W (-127.53537) Min. Hence, remote techniques such as seismicity and satellite altimetry provide important constraints on the tectonics, especially for the Tharp and Hollister transforms. M.D. M.
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. 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. "eltanin" in Chinese : "fracture zone" in Chinese : ; ; ; ; ; . . (2005). https://earthquake.usgs.gov/earthquakes/eventpage/us20009msm#executive, http://www.emsc-csem.org/Earthquake/earthquake.php?id=504225, http://earthquake.usgs.gov/earthquakes/eventpage/us100049ce#general_summary, Follow Earth Extremities on WordPress.com, MAGNITUDE6.9KERMADEC ISLANDS, NEWZEALAND, MAGNITUDE5.6SOUTHERN MID-ATLANTIC RIDGE, MAGNITUDE5.6EAST OF SOUTH SANDWICHISLANDS, MAGNITUDE6.9KERMADEC ISLANDS, NEW ZEALAND. Unless the presence of short spreading centres is taken into account, the application of simple plate cooling models using the entire length of transforms leads to underestimates of temperature and plate coupling.
We take this along with the distributions of events in time and longitude after 1976 (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. Similarly, earthquake recurrence is more difficult to examine for other long oceanic transform faults, such as those in the equatorial Atlantic, that have considerably smaller long-term slip rates. How that may vary along strike and affect seismic coupling is unknown. 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. Nettles
The RSS includes pelagic material from the early Cretaceous (140 Ma) which, coupled with the thickness of the sequence, does not fit with the normal scenario for the opening of the South Atlantic around the Aptian-Albian (125100 Ma). 4. It and some other segments of the three Eltanin transforms appear to be well coupled seismically. (1997) for the intermediate-period, fundamental-mode surface waves. Our knowledge of the Eltanin system is limited by the relatively high magnitude of completeness of events, Mw 5.4, and the paucity of aftershocks and forerunning events. The western part of the transverse ridge consists of fragments of uplifted oceanic crust and upper mantle. This bias suggests that the models used for CMT and ISC locations are not slow enough to the north and northeast along the East Pacific Rise. Sunrise, sunset, day length and solar time for Stockholm County. (2005), McGuire (2008) and Boettcher & McGuire (2009) find that some fault segments are characterized by a predominance of aseismic slip while others are fully coupled.
Dotted lines denote approximate locations of ridge segments. Menard
They were generally too small to generate stable CMT results. LOUISVILLE RIDGE AND ELTANIN FRACTURE ZONE 3053 west to isolated peaks superimposed on ridge segments in the southeast. 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. Sykes
While off-transform normal-faulting events and short intra-transform spreading centres are reasonably attributed to changes in plate motion, we do not find evidence from earthquake mechanisms along the Eltanin transforms that those faults are leaky' today in the sense proposed by Menard & Atwater (1969). Sykes
. 2. [3], Series of faults that offset the Pacific-Antarctic Ridge. 4. Who is Jason crabb mother and where is she? From 1990 to 2009, we selected events in the ISC, PDE, GCMT and surface wave detection (SWE) catalogues with at least one magnitude equal to or greater than 5.5. . R.
5. (1993) find that a 10 clockwise rotation of magnetic anomalies north of the Heezen transform occurred within the last 4 Ma, which would put it in extension. 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 waveforms were edited using the standard Global CMT (GCMT) automated waveform editor, and inverted using the standard Global CMT computer codes using corrections for 3-D earth structure in the calculation of synthetic seismograms (Ekstram .
R.A.
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. The risk of fracturing the proximal femur is high for individuals with metabolic bone disease or with low bone mass associated with advanced age. 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. . A break in the smooth trend of the ridge at latitude 37.5S has been recognized in both bathymetric and altimetric data.
. (1993) attribute it to one of those small spreading centres. None of our normal-faulting solutions are found adjacent to that part of the Tharp transform. Eltanin fracture zone Scope Notes: SE Pacific. . They differ in that hypocentres derived using body waves give the location of rupture initiation whereas CMT solutions give centroid locations and origin times. 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. Somewhat smaller estimates of W are obtained using a value of appropriate to the uppermost mantle. Lat: For full access to this pdf, sign in to an existing account, or purchase an annual subscription. The two largest (Mw 6.7 and 5.9) occurred well to the north of the transform in 2001 and 2007. 4. Table S1 in the Supporting Information lists the formal uncertainties of the revised centroid locations. Dziewonski
We calculate downdip widths of seismic coupling of about 5 km for four strongly coupled segments from observed moment rates and lengths along strike assuming earthquake activity accounts for the entire plate motion. The CMT methodology and format of the catalogue are described in Dziewonski (1981) and Ekstram (2005). The Eltanin Transform Fault and Fracture Zone is a series of six or seven dextral transform faults along ~800 km of the. Our results indicate considerable variation in moment release and hence in fault coupling along the strike of the three Eltanin transforms. T2=42r3/(GM), m3/(kgs2)m ^ { 3 } / \left( k g \cdot s ^ { 2 } \right) a generally flat zone extending from the shore to the shelf break continental margin shallow-water areas close to continent abyssal plain flat depositional surfaces that cover extensive portions of the deep-ocean basins The method that used most frequently to investigate sediment and rock layers of the sea floor is: fracture zones and transform faults flashcards quizlet. Stewart & Okal (1983) modelled P and reflected body waves for several strike-slip events along the Eltanin system. Wolfe et al. (1993) found another normal faulting event just to the south of the Menard transform fault at 49.5 S along the same plate boundary. Chou
As AABW flows through the Romanche Fracture Zone, salinity and temperature increase significantly. The mechanism in the GCMT catalogue indicates normal faulting, while the reanalysis resulted in a strike-slip mechanism. If those segments are not fully coupled, our calculations of downdip width, of course, are minimum estimates. Behn
. - 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. (1993) and Abercrombie & Ekstrm (2001) clearly include the uppermost oceanic mantle for earthquakes along three slower moving transform faults in the Equatorial Atlantic. That view comes in large part from assuming that the downdip (vertical) width of seismic faulting extends to about the 600 C isotherm as calculated using simple conductive plate cooling models where temperature at a given location along the transform is taken as the average on its two sides. 6). What is error code E01-5 on Toyota forklift. Hirth
Meteoritic Microfossils in Eltanin Impact Deposits. New Mw corresponds to seismic moment magnitude recomputed for this study. For the four seismically active fault segments in Table 1 we obtain similar downdip widths of seismic faulting of about 5 km assuming coupling at the full plate rate. The 2004 Parkfield earthquake of Mw 6.0 had a rupture length of 20-25 km (Johanson et al. I.A. 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 kinematics pattern in the region. Aseismic parts of the Heezen and Tharp fracture zones can be traced far to the northwest and southeast. Intermediate-period surface waves have been used in the GCMT analysis since 2004, and often are very useful for constraining solutions for earthquakes smaller than Mw= 5.5. The T-axis of a normal-faulting event in that area of Mw 5.4 in 1978 is inclined about 45 to the transform (Fig. 10.17882/59800. The four estimates of W in Table 1 range from 3.9 to 6.0 km. The fault segment between -665 and -680 km (green symbols in Fig. It is therefore unlikely that the event selection for 19902009 missed any earthquake with a moment magnitude greater than 5.5. We also used the same 3-D velocity model for our new CMT solutions. We show events characterized by a predominance of strike-slip faulting that we located since 1976 in red along with the few earthquakes in blue that involved a predominance of normal faulting.
G.
2 shows the areal distribution of strike-slip earthquakes Mw > 5.5 as a function of their recomputed magnitude, Mw, in red along the three transform faults of the Eltanin system. Since the length along strike, L, was not determined for individual earthquakes, for the calculations later we took a length of 105 km for the entire eastern end of the Heezen transform, which includes several segments that have ruptured in large shocks (Fig. L.R. The data since 1969 and those of Stewart & Okal (1983) for events back to 1920 indicate that earthquakes of Mw > 7 have not ruptured very long segments of any of the transforms. [7] , and M is in kg. Bathymetric Features 67%.