miocene extension and extensional folding in an anticlinal segment of the black mountains accommodation zone colorado river extensional corridor southwestern united states 1 recent studies demonstrate that rifts are characterized by linked tilt domains each containing a consistent polarity of normal faults and stratal tilt directions and that the transition between domains is typically through formation of accommodation zones and generally not through production of throughgoing transfer faults the mid miocene black mountains accommodation zone of southern nevada and western arizona is a well exposed example of an accommodation zone linking two regionally extensive and opposing tilt domains in the southeastern part of this zone near kingman arizona east dipping normal faults of the whipple tilt domain and west dipping normal faults of the lake mead domain coalesce across a relatively narrow region characterized by a series of linked extensional folds the geometry of these folds in this strike parallel portion of the accommodation zone is dictated by the geometry of the interdigitating normal faults of opposed polarity synclines formed where normal faults of opposite polarity face away from each other whereas anticlines formed where the opposed normal faults face each other opposed normal faults with small overlaps produced short folds with axial trends at significant angles to regional strike directions whereas large fault overlaps produce elongate folds parallel to faults analysis of faults shows that the folds are purely extensional and result from east northeast stretching and fault related tilting the structural geometry of this portion of the accommodation zone mirrors that of the black mountains accommodation zone more regionally with both transverse and strike parallel antithetic segments normal faults of both tilt domains lose displacement and terminate within the accommodation zone northwest of kingman arizona however isotopic dating of growth sequences and crosscutting relationships show that the initiation of the two fault systems in this area was not entirely synchronous and that west dipping faults of the lake mead domain began to form between 1 m y to 0 2 m y prior to east dipping faults of the whipple domain the accommodation zone formed above an active and evolving magmatic center that prior to rifting produced intermediate composition volcanic rocks and that during rifting produced voluminous rhyolite and basalt magmas

a soft linkage between major seismogenic fault systems in the central southern apennines italy evidence from low magnitude seismicity abstract we investigate the transfer zone and linkage between divergent extensional seismogenic fault systems on the border amid the central and southern apennines central italy these regional nw se striking sets include large seismogenic sources that caused major historical earthquakes m w 7 the faults in the northern part of the study area dip to the southwest those in the southern part dip to the northeast the sw dipping system abruzzi apennines terminates with the aremogna cinque miglia source the ne dipping system southern apennines terminates with the boiano basin source to test whether the transfer zone model applies to the central southern apennines border we analyzed and relocated seismicity that occurred from 2007 to 2011 between the aremogna cinque miglia and boiano basin sources where we expect the transfer zone seismicity is made of independent events md the spatial distribution of seismicity the geometry and kinematics of active faulting in the region and the results from previous geophysical studies allow us to contend the existence of a transfer zone between these seismogenic normal fault systems our data also allow us to recognize the activity of such transfer along the central part of the ortona roccamonfina line we infer that reverse in dip polarity between the two normal fault systems could also result from the passage between the diverse tectonic units composing the border between central and southern apennines

error analysis for the determination of tectonic rotation from paleomagnetic data appendix b is available with entire article on microfiche order from american geophysical union 2000 florida avenue n w washington d c 20009 document b83 001 2 50 payment must accompany order recent determinations of tectonic rotation and flattening from paleomagnetic data have exaggerated the size of the confidence limits or error bars by about 25 this has been caused by the misuse of conventional error propagation formulas to derive one degree of freedom error bars from a two dimensional cone of confidence 95 an analytical calculation which is valid when error bars are small shows that the correct error bars are 75 to 80 of the values derived in previous studies i have used numerical integration to check on the applicability of the analytical solution and to calculate error bars when the analytical approximation cannot be used the analytical approximation may be used whenever 95 is less than 10 and the mean inclination is not too close to vertical confidence limits given for tectonic rotation and flattening in recent literature are too large and should be reduced by 20 25 narrowing the error bars in this way permits a more accurate interpretation of paleomagnetic data

determination of escarpment age using morphologic analysis an example from the galilee northern israel we used topographic and structural data and very limited age control to perform quantitative morphometric analyses and to determine relative ages of escarpments bounded by late cenozoic normal faults in the galilee israel the galilee is an extensional zone composed of a series of uplifted and tilted blocks forming large escarpments built mainly of carbonate rocks two parameters used to discriminate tectonic stages are the ratio between the height of the escarpment and the total stratigraphic displacement l and the degree of concavity of escarpment slopes relative to a reference slope the only dated reference slope is mount tur9an 300 m high and formed by the tur9an fault system which has a total stratigraphic displacement of 625 m a basalt flow that delimits the age of the tur9an escarpment is dated to 4 23 0 23 ma and displaced 300 m which is identical to the present day topographic expression of this escarpment the l value for this escarpment is 0 5 the tur9an fault system was active prior to 4 23 ma at slow uplift rates that enabled erosion to maintain the gentle slope over which the basalt flowed increased offset rates following the basalt extrusion led to the formation of the escarpment the preservation of the basalt at the top of the escarpment indicates that erosional lowering of the upper surface of the tur9an block has been minor since its formation the l values indicate two stages of uplift an early stage during which offset rates were probably low enough that they did not form topography and a later stage that formed topography which is preserved the timing of the change in displacement rates from a slow continuous stage to a fast topography forming stage was determined by comparing the shape of the dated slope of tur9an to that of other slopes we conclude the following 1 generally the topographic profiles of different parts of each individual escarpment have similar shapes indicating similar ages 2 escarpments having slopes that are more concave or convex than the reference tur9an escarpment are older or younger than 4 ma respectively and 3 the galilee escarpments did not form simultaneously a few escarpments were already major morphologic features by the early to middle pliocene whereas the rest formed during the late pliocene morphometric analysis is a useful method for studying the geologic history of a landscape controlled by normal fault uplift and characterized by the absence of sediment deposition and where carbonate dissolution is the main erosional process this and similar approaches can be used to discriminate tectonic stages and understand the relationship between tectonic activity and surface processes in other extensional regions

evolution of vertical faults at an extensional plate boundary southwest iceland vertical faults having both opening and vertical displacements are common in southwest iceland and hypotheses vary regarding whether they propagated to the surface from below or from the surface downward we address this issue through a study of vertical faults and associated surface fracture zones in regions of both oblique and normal spreading in southwest iceland individual fracture segments are commonly rotated out of the general trend of the fracture zone suggesting oblique motion along subsurface normal faults these faults commonly breach the upper hinge lines of narrow monoclinal folds that flank many fault traces on the hanging wall side based on these field observations and the results of numerical models we propose that 60 758 dipping normal faults in the subsurface propagated to the surface from below vertical fractures formed at the upper tips of the faults at depths of between 250 and 500 m 25 50 of the fault length in response to stress concentrations along the tip line model results indicate that narrow monoclinal folds develop at the surface above these vertical fractures which subsequently breach the monoclines along the upper hinge line forming vertical fault scarps and open fissures at the surface if vertical fractures utilize pre existing cooling joints in basalt to connect directly to the surface the hanging wall is able to pull apart from the footwall without the development of a surface monocline along the fault trace q 2003 elsevier ltd all rights reserved

block rotation by strike slip faulting structural and paleomagnetic evidence geometric analysis shows that motion of sets of strike slip faults should cause block rotation otherwise the distorted fault domain would not fit with its surrounding the sense of the block rotation depends on the sense of fault slip and the spacing and orientation of the faults all of which can be obtained from structural data the predictions of the geometric model can then be independently tested by paleomagnetic measurements the model was tested in northern israel structural data reveal several domains of contemporaneous right and left lateral strike slip faults paleomagnetic measurements show that in a domain of nnw trending left lateral faults blocks rotated 23 3 8 2 clockwise and in a domain of right lateral faults blocks rotated 22 4 9 0 anticlockwise these results are in agreement with the prediction of the geometric analysis of the structure the combined results of the heterogenous deformation of the area resembles a pure shear which allows n s extension by about 1 3 in other domains rotations of 34 6 9 1 and 53 1 11 0 were found in their original orientation the left and right lateral faults intersected at angles of 60 70 enclosing the principal axis of shortening in accordance with theories of brittle failure as a result of block rotations this angle is now larger and may reach 110 the results demonstrate large block rotations in different senses in domains of strike slip faults the independent structural and paleomagnetic data can be interpreted within the framework of a simple geometric model northern israel is considered to be a good model for this efficient mechanism of intraplate deformation which is expected to occur in similar tectonic settings elsewhere

denali fault slip rates and holocene late pleistocene kinematics of central alaska the denali fault is the principal intracontinental strike slip fault accommodating deformation of interior alaska associated with the yakutat plate convergence we obtained the first quantitative late pleistocene holocene slip rates on the denali fault system from dating offset geomorphic features analysis of cosmogenic 10be concentrations in boulders n 27 and sediment n 13 collected at seven sites offset 25 170 m by the denali and totschunda faults gives average ages that range from 2 4 0 3 ka to 17 0 1 8 ka these offsets and ages yield late pleistocene holocene average slip rates of 9 4 1 6 12 1 1 7 and 8 4 2 2 mm yr 1 along the western central and eastern denali fault respectively and 6 0 1 2 mm yr 1 along the totschunda fault our results suggest a westward decrease in the mean pleistocene holocene slip rate this westward decrease likely results from partitioning of slip from the denali fault system to thrust faults to the north and west

relay ramp forms and normal fault linkages canyonlands national park utah fieldwork within a series of mesoscale grabens in southeast utah has revealed a particularly well exposed system of interlinked extensional faults a series of down faulted grabens are developed within a 460 m thick brittle layer of upper paleozoic sandstone and shale which overlies a ductile layer with a high gypsum content all the major grabens consist of two or more overlapping elements which are composed of fault segments these segments may be hard linked fault surfaces are joined or soft linked fault surfaces are isolated but linked by ductile strain of the rock volume between them in map view relay structures are defined as zones connecting the footwalls and hanging walls of overlapping fault segments representing soft linkage of fault segments in the canyonlands grabens the transfer of displacement between soft linked fault segments is characterized by well de fined dipping relay ramps commonly rotated and extended to accommodate the ductile strain between the overlapping fault segments relay ramps develop as ephemeral structures eventually becoming breached by hard linkage of the fault segments breakdown of ramps by breaching is part of the process of fault growth by segment linkage within the canyonlands graben system four orders of segmentation are present this may be a consequence of different scales of mechanical heterogeneity but evidence from the canyonlands grabens and elsewhere points to a fundamental process of discontinuous fault growth by segment linkage

extensional fault propagation folds mechanical models and observations from the modoc plateau northeastern california extensional fault propagation folds are produced by warping of material ahead of a growing normal fault we use field observations of surface breaking normal faults in the modoc plateau california in conjunction with three dimensional linear elastic boundary element computer models to address the mechanical controls on extensional fault propagation folds detailed topographic and structural maps of the near tip regions of several kilometer long faults reveal throw decreases rapidly toward the tip suggesting elliptical slip distributions fault parallel monoclinal folds are present beyond the tip with axes offset into the hanging wall and open fissures are common in the tip region parametric tests with the model show that the amplitude and form of folds at the fault terminations are influenced by slip distribution fault dip elastic properties of the rock and the presence or absence of a blind portion of the fault models reproduce the form of observed folds to first order and suggest that the faults both isolated and in relay zones are probably blind for some lateral extent beyond the surface break

morphological and structural relations in the galilee extensional domain northern israel the lower galilee and the yizre el valley northern israel are an extensional domain that has been developing since the miocene prior and contemporaneously to the development of the dead sea fault dsf it is a fan shaped region bounded in the east by the n s trending main trace of the dsf in the north by the bet kerem fault system and in the south by the nw se trending carmel fault the study area is characterized by high relief topography that follows fault bounded blocks and flexures at a wavelength of tens of km a synthesis of the morphologic structural relations across the entire galilee region suggests the following characteristics 1 blocks within the lower galilee tilt toward both the southern and northern boundaries forming two asymmetrical half graben structures opposite facing and oblique to one another 2 the lower galilee s neighboring blocks which are the upper galilee in the north and the carmel block in the southwest are topographically and structurally uplifted and tilted away from the lower galilee 3 the southern half graben along the carmel fault is topographically and structurally lower than the northern one combining structural and geological data with topographic analysis enables us to distinguish several stages of structural and morphological development in the region using a semi quantitative evolutionary model we explain the morpho structural evolution of the region our results indicate that the galilee developed as a set of two isostatically supported opposite facing half grabens under varying stress fields the southern one had started developing as early as the early miocene prior to the formation of the dsf the northern and younger one has been developing since the middle pliocene as part of the extension process in the galilee elevation differences between the two half grabens and their bounding blocks are explained by differences in isostatic subsidence due to sedimentary loading and uplift of the northern half graben due to differential influences of the regional folding d 2003 elsevier b v all rights reserved

scaling of transfer zones in the british isles widths of transfer zones between stepping normal faults obey power law scaling relationships probably from widths of millimetres to tens or hundreds of kilometres relay ramp widths in the mesozoic sedimentary rocks of the somerset coast obey a power law up to 50 m above which there is a censoring effect caused by the width of the wave cut platform a structural map of the british isles indicates that transfer zones obey a power law up to widths of at least 250 km this indicates that normal faults can interact over tens or hundreds of kilometres especially where transfer zones occur between stepping half grabens interaction is therefore another aspect of faulting that obeys fractal behaviour

geometry and development of relay ramps in normal fault systems relay ramps occur between normal fault segments that overstep in map view the geometry and evolution of exposure scale relay ramps are described from the somerset coast england and are compared with larger scale ramps from elsewhere relay ramps can be classified into four groups based on the degree of interaction and linkage between the overstepping segments these groups are interpreted as being evolutionary stages in stage 1 the segments do not interact stage 2 involves the reorientation of bedding between two interacting faults to produce a relay ramp in stage 3 connecting fractures start to break the relay ramp stage 4 is when the relay ramp is destroyed to produce a single fault that has an along strike bend these evolutionary stages can develop through ti e but they can also be seen spatially a branch line between normal faults or an along strike bend may represent a stage 4 relay with progressively earlier stages occurring updip or downdip characteristic variability in displacement distance profiles for fault segments and linked faults accompanies the interaction and linkage processes displacement transfer by relay ramps is accompanied by steep displacement gradients along fault segments at oversteps relay ramps often contribute to a minimum in total fault displacement at a linkage point

paleoseismic observations along the langshan range front fault hetao basin china tectonic and seismic implications abstract the langshan range front fault lrf is an active holocene normal fault that borders langshan mountain and the hetao basin northwest of the ordos plateau china in this study paleoseismic trenching was undertaken at three sites north south dongshen village tc1 qingshan tc2 and wulanhashao tc3 the paleoevents ed1 ed2 ed3 from tc1 were constrained to 6 0 1 3 9 6 2 0 and 19 7 4 2 ka respectively the single paleoevent eq1 from tc2 was constrained to about 6 7 0 1 ka and the paleoevents ew1 ew2 and ew3 from tc3 were constrained to 2 3 0 4 6 0 1 0 and before 7 0 ka respectively with reference to previous research the holocene earthquake sequence of the lrf can be established as 2 30 2 43 e1 3 06 4 41 e2 6 71 6 80 e3 7 60 9 81 e4 and 19 70 4 20 e5 ka bp events e1 e3 and e4 might have been caused by events with magnitudes of mw 7 6 7 8 that ruptured the entire lrf event e2 might have been smaller magnitude about m7 0 and ruptured only a portion of the fault the vertical slip rate of the lrf at the qingshan site is inferred as 0 9 or 1 4 1 6 mm year in the last 6 8 ka the slip rate at wulanhashao is considered to have been close to but not

seismology speed and size of the sumatra earthquake we now have a clearer picture of the seismic features of last year s gigantic event our seismological results reveal that indonesia s devastating sumatra andaman earthquake on 26 december 2004 was 2 5 times larger than initial reports suggested second only to the 1960 chilean earthquake in recorded magnitude they indicate that it slowly released its energy by slip along a 1 200 km fault generating a long rupture that contributed to the subsequent tsunami now that the entire rupture zone has slipped the strain accumulated from the subduction of the indian plate beneath the burma microplate has been released and there is no immediate danger of a similar tsunami being generated on this part of the plate boundary although large earthquakes on segments to the south still present a threat

three dimensional distinct element modelling of relay growth and breaching along normal faults three dimensional numerical models of neutral i e slip parallel relay zones on normal faults that cut massive sandstone host rocks have been constructed using the distinct element method code particle flow code in 3 d pfc3d the models successfully reproduce the geometries displacement profiles and strains observed in natural relay zones in contrast to boundary element method simulations the modelled relay ramps dip towards the hanging wall consistent with observations of most natural relay zones the modelling shows that relay zones are stable structures that grow by progressive rotation of an approximately planar relay ramp without significant propagation of the relay bounding faults prior to breaching stable growth is terminated when a breaching fault propagates across the top or bottom of the relay ramp breaching fault propagation is not instantaneous and the ramp continues to rotate and therefore transfer displacement between the relay bounding faults until they become fully hard linked following hard linkage displacement is accommodated by slip on the through going fault surface the modelling results confirm previous conceptual models of relay growth and breaching based on geometric and kinematic analysis of natural relay zones

40ar 39ar age constraints for the jaramillo normal subchron and the matuyama brunhes geomagnetic boundary our mid pleistocene 4oar 39ar age recalibration of the geomagnetic polarity timescale is nearly in accord with the oxygen isotope climate record calibration of the astronomical timescale proposed by johnson 1982 and shackleton et al 1990 4oar 39ar ages of a normally magnetized rhyolite dome in the valles caldera northern mexico yielded a weighted mean age of 1 004 0 019 ma a k ar age of 0 909 0 019 ma for this rock by doell and dalrymple 1966 was the linchpin for the recognition and calibration of the jaramillo normal subchron jns other 4oar 39ar ages from the vailes caldera and 4oar 39ar ages of ivory coast tektites indicate that the jns began at about 1 11 ma and ended before 0 92 ma probably near 0 97 ma the matuyama brunhes boundary occurred between 0 79 ma and 0 76 ma on the basis of 4oar 39ar sanidine ages from 1 three reversely magnetized rhyolite domes of the valles caldera 0 793 0 018 ma 0 794 0 007 ma and 0 812 0 023 ma and pumice 0 789 0 006 ma from the reversely magnetized oldest toba tuff of sumatra and 2 pumice 0 764 0 005 ma and 0 757 0 009 ma from the lower and upper units of the normally magnetized bishop tuff the age of the boundary may be close to 0 77 ma as deduced from rates of sedimentation in ancient lake bonneville utah increasingly aware that the polarity of earth s magnetic field has changed repeatedly through geologic time and isotopic dating of these polarity reversals resulted in a geomagnetic polarity time scale gpts for the late cenozoic this combined paleomagnetic and isotopic research played a pivotal role in confirming plate tectonic theory glen 19821 which revolutionized the earth sciences continual refinement of isotopic ages which define the gpts has increased the usefulness of geomagnetic polarity reversals as marker hori zons in many types of geologic studies we present 4oar 39ar data and ages for some key volcanic units that support changes in the isotopic age chronology of the gpts using volcanic rocks erupted near the time of the geologically youngest two geomagnetic polarity reversals figure 1 the older of the two reversals originally called by doell and dalrymple 1966 the jaramillo event is now named the jaramillo normal subchron jns it is recorded in middle pleistocene rocks as a brief episode of normal polar ity within the late matuyama chron the younger of the two called the matuyama brunhes boundary mbb is regis tered in middle pleistocene rocks worldwide and consists of

rupture process of the 2004 sumatra andaman earthquake the 26 december 2004 sumatra andaman earthquake initiated slowly with small slip and a slow rupture speed for the first 40 to 60 seconds then the rupture expanded at a speed of about 2 5 kilometers per second toward the north northwest extending 1200 to 1300 kilometers along the andaman trough peak displacements reached 15 meters along a 600 kilometer segment of the plate boundary offshore of northwestern sumatra and the southern nicobar islands slip was less in the northern 400 to 500 kilometers of the aftershock zone and at least some slip in that region may have occurred on a time scale beyond the seismic band

estimation of tsunami hazard in new zealand due to south american earthquakes we develop a probabilistic model for estimating the tsunami hazard along the coast of new zealand due to plate interface earthquakes along the south american subduction zone to do this we develop statistical and physical models for several stages in the process of tsunami generation and propagation and develop a method for combining these models to produce hazard estimates using a monte carlo technique this process is largely analogous to that used for seismic hazard modelling but is distinguished from it by the use of a physical model to represent the tsunami propagation as opposed to the use of empirical attenuation models for probabilistic seismic hazard analysis

timing of large earthquakes since a d 800 on the mission creek strand of the san andreas fault zone at thousand palms oasis near palm springs california paleoseismic investigations across the mission creek strand of the san andreas fault at thousand palms oasis indicate that four and probably five surface rupturing earthquakes occurred during the past 1200 years calendar age estimates for these earthquakes are based on a chronological model that incorporates radiocarbon dates from 18 in situ burn layers and stratigraphic ordering constraints these five earthquakes occurred in about a d 825 770 890 mean 95 range a d 982 840 1150 a d 1231 1170 1290 a d 1502 1450 1555 and after a date in the range of a d 1520 1680 the most recent surface rupturing earthquake at thousand palms is likely the same as the a d 1676 35 event at indio reported by sieh and williams 1990 each of the past five earthquakes recorded on the san andreas fault in the coachella valley strongly overlaps in time with an event at the wrightwood paleoseismic site about 120 km northwest of thousand palms oasis correlation of events between these two sites suggests that at least the southernmost 200 km of the san andreas fault zone may have ruptured in each earthquake the average repeat time for surface rupturing earthquakes on the san andreas fault in the coachella valley is 215 25 years whereas the elapsed time since the most recent event is 326 35 years this suggests the southernmost san andreas fault zone likely is very near failure the thousand palms oasis site is underlain by a series of six channels cut and filled since about a d 800 that cross the fault at high angles a channel margin about 900 years old is offset right laterally 2 0 0 5 m indicating a slip rate of 4 2 mm yr this slip rate is low relative to geodetic and other geologic slip rate estimates 26 2 mm yr and about 23 35 mm yr respectively on the southernmost san andreas fault zone possibly because 1 the site is located in a small step over in the fault trace and so the rate is not be representative of the mission creek fault 2 slip is partitioned northward from the san andreas fault and into the eastern california shear zone and or 3 slip is partitioned onto the banning strand of the san andreas fault zone

fault displacement rates on a range of timescales abstract displacements on tectonic faults primarily accrue during earthquakes at rates that vary through time to examine the processes that underlie the temporal changes in fault displacement rates we analyse displacements and displacement rates for time periods from the present to 5 10 20 300 500 1000 and 5000 kyr for 261 active reverse or normal faults from a worldwide dataset displacement rates depart from million year average rates by up to three orders of magnitude with the size of these departures inversely related to the duration of the sample period and to fault length short term 20 kyr displacement rates generally span a greater range on small faults than large a feature which suggests more variable growth on smaller faults simple earthquake slip modeling shows that variations in displacement rates require changes in both recurrence interval and slip per event and do not support the characteristic slip earthquake model as long as fault system strain rates are uniform displacement rates generally become constant over time periods between 20 and 300 kyr with the length of time required to reach stability being inversely related to the regional basin wide strain rates stable long term displacement rates and fluctuations in earthquake recurrence intervals and slip arise in part due to fault interactions

deformed streams reveal growth and linkage of a normal fault array in the canyonlands graben utah we use the deformation of streams by the growth of active normal faults within the canyonlands graben of southeastern utah to constrain the displacement evolution of a fault array during segment interaction and linkage coupling fault displacement data with geomorphic analysis of present day streams and paleostreams permits sequential reconstruction of a three segment fault array from initial component segments to its final displacement geometry our results show that although segment interaction causes enhanced displacement addition at overlap zones postlinkage displacement accumulation is significant and permits array equilibration to a displacement length ratio characteristic of a single fault evidence of stream disequilibrium indicates that this postlinkage displacement addition was rapid compared to that during the fault interaction phase

geomorphological analysis of neotectonic deformation northern owens valley california at the western edge of the basin and range province the owens valley is the site of active seismicity and deformation morphometric analyses of three geomorphological features are used to determine the patterns and rates of neotectonic deformation l a network of pleistocene channels cut on top of the bishop tuff 2 uplifted terraces of the owens river and 3 alluvial fans of the white mountain front

analysis of environmental controls on tsunami deposit texture abstract tsunamis transport large amounts of sediment and can leave recognisable signatures in the landscape the form and composition of onshore tsunami deposits are a function of wave dynamics sediment availability and characteristics of the local environment the latter of which also partially controls preservation of the deposit this research reviews these relationships in a global context and assesses the connection between tsunami deposit particle size and four controlling parameters climate temperature and rainfall density of tsunami sediments degree of coastal protection and distance between tsunami source and sediment deposition an international dataset of tsunami deposit locations and texture was compiled from published literature and existing databases values for environmental variables were calculated for each location from global datasets of temperature rainfall coastline shape and tsunami source locations spearman s rank order correlation principal component analysis pca and hierarchical cluster analysis ca were used to analyse relationships between these variables pca results show an inverse relationship between particle size and sediment density climate variables and distance from source ca results support this suggesting a cluster structure controlled primarily by particle size and secondly by climate and sediment density these relationships can be explained by the influence of the environment on antecedent morphology and the composition of sediments available for tsunami transport

the 2010 chilean tsunami off the west coast of canada and the northwest coast of the united states the major m w 8 8 chilean earthquake of 27 february 2010 generated a trans oceanic tsunami that was observed throughout the pacific ocean waves associated with this event had features similar to those of the 1960 tsunami generated in the same region by the great m w 9 5 1960 chilean earthquake both tsunamis were clearly observed on the coast of british columbia the 1960 tsunami was measured by 17 analog pen and paper tide gauges while the 2010 tsunami was measured by 11 modern digital coastal tide gauges four neptune canada bottom pressure recorders located offshore from southern vancouver island and two nearby open ocean dart stations the 2010 records were augmented by data from seven noaa tide gauges on the coast of washington state this study examines the principal characteristics of the waves from the 2010 event height period duration and arrival and travel times and compares these properties for the west coast of canada with corresponding properties of the 1960 tsunami results show that the 2010 waves were approximately 3 5 times smaller than the 1960 waves and reached the british columbia coast 1 h earlier the maximum 2010 wave heights were observed at port alberni 98 4 cm and winter harbour 68 3 cm the observed periods ranged from 12 min at port hardy to 110 120 min at prince rupert and port alberni and 150 min at bamfield the open ocean records had maximum wave heights of 6 11 cm and typical periods of 7 and 15 min coastal and open ocean tsunami records revealed persistent oscillations that rang for 3 4 days tsunami energy occupied a broad band of periods from 3 to 300 min estimation of the inverse celerity vectors from cross correlation analysis of the deep sea tsunami records shows that the tsunami waves underwent refraction as they approached the coast of vancouver island with the direction of the incoming waves changing from an initial direction of 340 true to a direction of 15 true for the second train of waves that arrived 7 h later after possible reflection from the marquesas and hawaiian islands

dating offset fans along the mojave section of the san andreas fault using cosmogenic 26al and 10be analysis of cosmogenic 1 0 be and 2 6 al in samples collected from exposed boulders n 20 and from buried sediment n 3 from offset fans along the san andreas fault near little rock california yielded ages ranging from 16 to 413 ka which increase with dis lance from their source at the mouth of little rock creek in order to determine the age of the relatively younger fans the erosion rate of the boulders and the cosmogenic nuclide inheritance from exposure prior to deposition in the fan were established cosmogenic nuclide inheritance values that range between 8 5 x 10 3 and 196 10 3 atoms 1 0 be g 1 quartz were determined by measuring the concentrations and ratios of 1 0 be and 2 6 al in boulders n 10 and fine sediment n 7 at the outlet of the present active stream boulder erosion rate ranging between 17 and 160 mm k y 1 was estimated by measuring 1 0 be and 2 6 al concentrations in nearby bedrock outcrops n 8 since the boulders on the fans represent the most resistant rocks in this environment we used the lowest rate for the age calculations monte carlo simulations were used to determine ages of 16 5 and 29 7 ka for the two younger fan surfaces older fans older than 100 ka were dated by analyzing 1 0 be and 2 6 al concentrations in buried sand samples the ages of the three oldest fans range between 227 242 and 413 185 ka although fan age determinations are accompanied by large uncertainties the results of this study show a clear trend of increasing fan ages with increasing distance from the source near little rock creek and provide a long term slip rate along this section of the san andreas fault slip rate along the mojave section of the san andreas fault for the past 413 k y can be determined in several ways the average slip rate calculated from the individual fan ages is 4 2 0 9 cm yr 1 a linear regression through the data points implies a slip rate of 3 7 1 0 cm yr 1 a most probable slip rate of 3 0 1 0 cm yr 1 is determined by using a 2 test these rates suggest that the average slip along the mojave section of the san andreas fault has been relatively constant over this time period the slip rate along the mojave section of the san andreas fault determined in this study agrees well with previous slip rate calculations for the quaternary

evidence for large earthquakes on the san andreas fault at the wrightwood california paleoseismic site a d 500 to present we present structural and stratigraphic evidence from a paleoseismic site near wrightwood california for 14 large earthquakes that occurred on the southern san andreas fault during the past 1500 years in a network of 38 trenches and creek bank exposures we have exposed a composite section of interbedded debris flow deposits and thin peat layers more than 24 m thick fluvial deposits occur along the northern margin of the site the site is a 150 m wide zone of deformation bounded on the surface by a main fault zone along the northwest margin and a secondary fault zone to the southwest evidence for most of the 14 earthquakes occurs along structures within both zones we identify paleoearthquake horizons using in filled fissures scarps multiple rupture terminations and widespread folding and tilting of beds ages of stratigraphic units and earthquakes are constrained by historic data and 72 14c ages mostly from samples of peat and some from plant fibers wood pine cones and charcoal comparison of the long well resolved paleoseimic record at wrightwood with records at other sites along the fault indicates that rupture lengths of past earthquakes were at least 100 km long paleoseismic records at sites in the coachella valley suggest that each of the past five large earthquakes recorded there ruptured the fault at least as far northwest as wrightwood comparisons with event chronologies at pallett creek and sites to the northwest suggests that approximately the same part of the fault that ruptured in 1857 may also have failed in the early to mid sixteenth century and several other times during the past 1200 years records at pallett creek and pitman canyon suggest that in addition to the 14 earthquakes we document one and possibly two other large earthquakes ruptured the part of the fault including wrightwood since about a d 500 these observations and elapsed times that are significantly longer than mean recurrence intervals at wrightwood and sites to the southeast suggest that at least the southermost 200 km of the san andreas fault is near failure

extreme inundation flows during the hokkaido nansei oki tsunami the tsunami generated by the july 12 1993 hokkaido nansei oki mw 7 8 earthquake produced in japan the worst local tsunami related death toll in fifty years with estimated 10 18m sec overland flow velocities and 30m runup these extreme values are the largest recorded in japan this century and are among the highest ever documented for non landslide generated tsunamis we model this event to confirm the estimated overland flow velocities and we find that given reasonable ground deformation data current state of the art shallow water wave models can predict tsunami inundation correctly including extreme runup current velocities and overland flow we find that even small local topographic structures affect the runup to first order and that the resolution of the bathymetric data is more important than the grid resolution our results qualitatively suggest that for this event coastal inundation is more correlated with inundation velocities than with inundation heights explaining also why threshold type modeling has substantially underpredicted coastal inundation for this and other recent events

displacement history of a limestone normal fault scarp northern israel from cosmogenic 36cl the abundance of cosmogenic 36 cl measured in 41 limestone samples from a 9 m high bedrock fault scarp allows us to construct the 14 kyr fault displacement history of the nahef east normal fault northern israel 300 m above sea level n33 latitude the nahef east fault is one of a series of fault scarps located along the 700 m high zurim escarpment a major geomorphic feature samples at the top of the scarp have the highest nuclide concentrations 79 x 10 4 atoms g rock 1 samples at the base have the lowest 11 x 10 4 atoms g rock 1 using chemical data from the samples nahef east fault scarp geometry and surface and subsurface production rates for the 36 cl producing reactions we have constructed a numerical model that calculates 36 cl accumulation on a scarp through time given a series of unique displacement scenarios the resulting model 36 cl concentrations are compared to those measured in the scarp samples faulting histories that result in a good match between measured and modeled 36 cl abundances show three distinct periods of fault activity during the past 14 kyr with over 6 vertical meters of motion occurring during a 3 kyr time period in the middle holocene smaller amounts of displacement occurred before and after the period of most rapid motion the episodic behavior of the nahef east fault indicates that the average displacement rate of this fault system has varied through time

hierarchic three dimensional structure and slip partitioning in the western dead sea pull apart 1 rifted basins are bounded by marginal belts with fault networks and flexures we analyze the internal structure of such a belt the western margins of the dead sea basin this basin is 150 km long 15 20 km wide with more than 10 km of sediment fill and it is currently subsiding due to slip of the dead sea pull apart the western margin of the dead sea basin is an elongated n s belt with an intricate three dimensional 3 d pattern of zigzag faults flexures and joints the dominant structures are four sets of oblique normal faults arranged in orthorhombic symmetry the faults are steep with prevalent strike directions of nnw and nne large flexures developed along and above these faults forming tilted blocks and localized asymmetric folds two sets of subvertical joints that dominate the area trend nne and nnw subparallel to the strikes of the dominant fault sets the parallel relations between these structures at all scales suggest that they formed during a single tectonic phase three dimensional fault modeling reveals a 3 d strain field with a large vertical shortening a minor horizontal shortening in n s direction belt parallel and a large horizontal e w extension basinward the calculated stress fields associated with the zigzag fault segments are compatible with the observed fault parallel flexures further the calculations predict the formation of local tensile belts above the faults and these tensile belts could explain the penecontemporaneous development of the two joint sets architecture similar to the western margins of the dead sea basin is likely to develop on rifted margins wherever 3 d deformation is required by the rifting kinematics

merging tsunamis of the 2011 tohoku oki earthquake detected over the open ocean 1 tsunamis often travel long distances without losing power and severely devastate some coastal areas while leaving others with little damage this unpredictable situation has been a major challenge for accurate and timely tsunami forecasting to facilitate early warning and possible evacuations of affected coastal communities without disturbing the lives of others here we show evidence from satellite altimetry observations of the 2011 tohoku oki earthquake induced tsunami that sheds light on this issue three satellites observed the same tsunami front and for the first time one of them recorded a tsunami height about twice as high as that of the other two model simulations based on the gps derived earthquake source and constrained by measurements of seafloor motions near the hypocenter confirm that the amplified tsunami is one of several jets formed through topographic refraction when tsunamis travel along ocean ridges and seamount chains in the pacific ocean this process caused the tsunami front to merge as it propagates resulting in the doubling of the wave height and destructive potential in certain directions we conclude that the potential of merging tsunamis should be emphasized in mapping tsunami hazards and assessing risk levels at key coastal facilities

changes in holocene paleoseismic activity in the hula pull apart basin dead sea rift northern israel abstract paleoseismic analysis of the azaz fault segment of the dead sea fault northern israel indicates that this region was subjected to intermittent periods of strong seismicity and quiescence during the latest pleistocene and the holocene the azaz fault forms the eastern margin of the hula valley a pull apart basin between two left stepping segments of the dead sea fault the fault is currently inactive but it displaces a 25 30 ka travertine in the northeastern corner of the hula valley and near surface marsh sediments inside the valley two trenches excavated across a 15 20 m high fault scarp near kefar szold expose fluvial and colluvial sequences showing clear evidence of recent tectonics one trench exposes well sorted bedded alluvial sediments comprising two upward fining units each capped by a weakly developed paleosol the sediments were deposited on the down faulted block and are bounded in the east by the fault scarp the second trench uncovers fine colluvial sediments cross cut by a wide fault parallel fissure filled by collapsed sediments in both trenches the lower sedimentary unit is capped by a coarse colluvium containing boulders up to 1 5 m in size the colluvium shows no clear bedding and has a weakly developed paleosol on top optically stimulated luminescence dating of the lower fluvial sequence shows that its age ranges between 12 ka at the base to 6 ka at the top while the middle part of the overlying colluvium is ca 4 8 ka the relation between the lower fluvial units and the fault indicates that at least two large scale earthquakes occurred in the early holocene each one resulting in a 1 1 5 m high fault scarp during this seismically active period no coarse colluvial sediments were deposited along the fault trace and thus the region must have had low tectonic relief the clear contact with the overlying coarse colluvium reflects a middle holocene rapid change to the present high steep relief this change was achieved by frequent strong seismic events which triggered colluvial processes and prevented stratification and soil formation on the slope the soil on the present slope reflects a quiescent period that has lasted at least several hundred years during which stress has accumulated and seismic risk increased

tsunami as agents of geomorphic change in mid ocean reef islands low lying atoll islands appear highly vulnerable to the effects of climate change and extreme natural events potentially disastrous effects of future sea level rise have been inferred in many studies and the actual impacts of tropical storms on island destruction and formation have been well documented in contrast the role of tsunami in the geomorphic development of atoll islands has not been investigated the sumatran earthquake of 26 december 2004 generated a tsunami that reached the maldives 2500 km away with waves up to 2 5 m high observations on the geomorphic changes resulting from the tsunami are detailed here based on pre and post tsunami profile measurements of island beach and reef topography and gps surveys of the planform shape of islands and beaches of 11 uninhabited islands in south maalhosmadulu atoll maldives erosional and depositional impacts were observed on all islands and these have been quantified in general the changes were of a minor nature with a maximum reduction in island area of 9 and average of 3 75 rather the tsunami accentuated predictable seasonal oscillations in shoreline change including localised erosion reflected in fresh scarps and seepage gullies depositional features in the form of sand sheets and sand lobes emplaced on the vegetated island surfaces provide clear evidence that the tsunami waves washed over parts of all the islands both erosional scarps and overwash deposits were concentrated at the tsunami exposed eastern sides of the islands impacts on leeward shores were primarily accretionary in the form of spit and cuspate foreland extension whereas the nature and magnitude of intra and inter island impacts was variable an east to west decline in aggregate effects was noted detailed consideration of the morphodynamic interaction between the tsunami waves and island morphology show that this cross atoll gradient resulted not just from the reduction in tsunami energy as it passed through the atoll but also from variations in elevation of the encircling island ridge and the quantity and distribution of sediment in the antecedent beach a conceptual model identifying the sequence of changes to individual islands supports the observational data and the pattern of geomorphic changes resulting from the tsunami this model leads to consideration of the longer term impacts of the tsunami on the future stability of islands four scenarios are presented each of which has a different island beach sediment budget and different relaxation time to achieve dynamic equilibrium

from mass wasting to slope stabilization putting constrains on a tectonically induced transition in slope erosion mode a case study in the judea hills israel calcrete coated remnants of landslide debris and alluvial deposits are exposed along the presently stable hillslopes of the soreq drainage judea hills israel these remnants indicate that a transition from landslide dominated terrain to dissolution controlled hillslope erosion had occurred this transition possibly occurred due to the significant decrease in tectonic uplift during the late cenozoic the study area is characterized by sub humid mediterranean climate the drainage hillslopes are typically mantled by thick calcrete crusts overlying upper cretaceous marine carbonate rocks using tt osl dating of aeolian quartz grains incorporated in the calcrete which cements an ancient landslide deposit we conclude that incision of 100 m occurred from 1056 262 to 688 86 ka due to 0 3 westward tilt of the region such incision invoked high frequency of landslide activity in the drainage the ages of a younger landslide remnant alluvial terrace and alluvial fan all situated only a few meters above the present level of the active streambed range between 688 86 ka and 244 25 ka and indicate that since 688 86 the soreq base level had stabilized and that landslide activity decreased significantly by the middle pleistocene copyright 2012 john wiley sons ltd

elastic dislocation modeling of wrinkle ridges on mars wrinkle ridges are one of the most common landforms on mars although it is generally agreed that they are compressional tectonic features formed by folding and thrust faulting there is no consensus on the number of faults involved the geometry of the faults or the maximum fault depth the topography of martian wrinkle ridges in solis planum and lunae planum has been studied using mola data as determined in previous studies the topography shows that most wrinkle ridges are a composite of two landforms a broad low relief arch and a superimposed ridge constrained by mola topographic profiles the geometry and parameters of the faults associated with wrinkle ridges have been modeled the best fits are obtained with a blind listric thrust fault that flattens into a decollement the listric fault geometry is approximated by a series of linear connecting segments with varying dips the major morphologic elements of wrinkle ridges can be matched by varying the displacement on the different fault segments modeling of large scale wrinkle ridges indicates that the maximum depth of faulting or depth to the decollement is about 4 5 km this may correspond to the depth of the contact between the ridged plains volcanic sequence and the underlying megabreccia the results suggest that wrinkle ridge thrust faults are shallow rooted and reflect thin skinned deformation

the global reach of the 26 december 2004 sumatra tsunami numerical model simulations combined with tide gauge and satellite altimetry data reveal that wave amplitudes directionality and global propagation patterns of the 26 december 2004 sumatra tsunami were primarily determined by the orientation and intensity of the offshore seismic line source and subsequently by the trapping effect of mid ocean ridge topographic waveguides

mass movement induced tsunami hazard on perialpine lake lucerne switzerland scenarios and numerical experiments previous studies of the sediments of lake lucerne have shown that massive subaqueous mass movements affecting unconsolidated sediments on lateral slopes are a common process in this lake and in view of historical reports describing damaging waves on the lake it was suggested that tsunamis generated by mass movements represent a considerable natural hazard on the lakeshores newly performed numerical simulations combining two dimensional depth averaged models for mass movement propagation and for tsunami generation propagation and inundation reproduce a number of reported tsunami effects four analysed mass movement scenarios three based on documented slope failures involving volumes of 5 5 to 20 8 106 m3 show peak wave heights of several metres and maximum runup of 6 to 10 m in the directly affected basins while effects in neighbouring basins are less drastic the tsunamis cause large scale inundation over distances of several hundred metres on flat alluvial plains close to the mass movement source areas basins at the ends of the lake experience regular water level oscillations with characteristic periods of several minutes the vulnerability of potentially affected areas has increased dramatically since the times of the damaging historical events recommending a thorough evaluation of the hazard

sandbox models of relay ramp structure and evolution relay ramps are a common feature formed during the growth of normal fault systems we performed analogue experiments to investigate the structure and evolution of relay ramps an extending rubber sheet induces extension at the base of a sand pack brittle crust analogue silicone bars between the rubber and the sand control the location of fault nucleation we tested the role of fault spacing fault length overlap length and fault strike in the evolution of relay ramps the modelled relay ramps evolved in three stages characterized by the growth of the normal faults their interaction and linkage interaction and linkage occurred only when the combined length of the two interacting faults was larger than eight times their spacing the length to width ratio of the relay ramps during the interaction stage showed preferred geometries clustering around three the propagation of the fault tips was observed both before and after the linkage stage overlap length and spacing relations of the modelled relay ramps are similar to those in nature at different scales and can be explained using existing mechanical models nevertheless the further propagation of the fault tips after linkage has not been described previously

timing of relay ramp growth and normal fault linkage upper galilee northern israel we investigate a kilometer scale steep relay rampstructure in the galilee northern israel the data indi cate an asymmetric fold above the buried tip of thesouthern boundary fault as well as at the lower partof the ramp structural analysis suggests that the buriedtip of the bounding fault is only a few hundred metersbelow the surface a sequence of colluvial wedges exposed at the base of the southern flank of the relayramp over the blind tip of the boundary fault presentssuccessively decreasing angles from 67 at the bottomto 30 at the top the lower three wedges rest at anglesgreater than the angle of repose suggesting tilting dur ing and after deposition we suggest that the increasingangle of the wedges is the result of the development ofthe monocline over the buried tip ofthe boundaryfault which in turn reflects the development of the entirerelay ramp structure paleomagnetic measurements testthis hypothesis samples from three of the four lowerwedges and the carbonate fill in the fractured bedrockyield northerly declination and positive inclination inclination anomalies are 19 4 3 3 and 11 3 1 8 for the fractured bedrock and the wedges respec tively these anomalies reflect part of the tilt paleo magnetic measurements and optically stimulatedluminescence osl constrain the time of initial defor mation of the monocline above the southern boundaryfault between 780 ka and 461 75 ka osl age ofwedge 1 and the termination of deformation to 176 22 ka osl age of wedge 5 these bounding agessuggest tilting rates that range between 1 16 kyrand 1 8 kyr termination of tilting along the south ern flank of the relay ramp and the fact that the tipof the buried normal fault is only a few hundreds ofmeters below the surface suggest that the relay rampmay be close to being breached by a connecting fault

oblique slip and the geometry of normal fault linkage mechanics and a case study from the basin and range in oregon abstract map patterns of normal fault linkages near summer lake oregon show a systematic relationship between echelon step sense oblique slip sense and the position of linking faults where the step sense is the same as the sense of oblique slip e g left step and left oblique slip the faults are linked in the lower part of their relay ramp where the step sense and slip sense are opposite e g left step and right oblique slip the faults are linked in the upper part of the ramp a boundary element code is used to calculate the stress field around echelon normal faults during oblique slip and the model results reveal a relationship similar to the field observations if step sense and oblique slip sense are the same there is a greater potential for deformation ahead of the tip of the front fault and in the lower part of the ramp if step sense and oblique slip sense are opposite there is a greater potential for deformation ahead of the tip of the rear fault and in the upper part of the ramp the field model comparison confirms that oblique slip modifies the mechanical interaction among fault segments and thus influences fault growth and the geometry of fault linkage

propagation of normal faults to the surface in basalt koae fault system hawaii normal fault scarps of the koae fault system on kilauea volcano consistently display locally breached monoclines underlain by prominent cavities deep gaping fissures on the footwall finer fissures on the hanging wall and buckles at the scarp base elastic analyses reveal that this assemblage forms as a fault propagates up towards the surface rather than down from it models of a planar blind normal fault with a dip exceeding 60 yield a monocline with a tensile stress concentration at the surface where gaping fissures occur a stronger subsurface tensile stress concentration near the blind fault tip where cavities occur and a compressive stress concentration at the surface where buckles occur the footwall fissures grow down from the tensile stress concentration at the surface and link with a fault as its scarp grows in contrast the cavities initiate at depth near the fault tip and propagate with it up towards the surface the hanging wall fissures apparently open in response to slip on late forming blind antithetic faults near the surface stoped blocks derived from footwall fissure walls help prop the footwall fissures open as a normal fault breaches the surface the fissures cavities and scarp rubble provide highly conductive hydraulic pathways

tsunamis on the pacific coast of canada recorded in 1994 2007 in the last 15 years there have been 16 tsunami events recorded at tide stations on the pacific coast of canada eleven of these events were from distant sources covering almost all regions of the pacific as well as the december 26 2004 sumatra tsunami in the indian ocean three tsunamis were generated by local or regional earthquakes and two were meteorological tsunamis the earliest four events which occurred in the period 1994 1996 were recorded on analogue recorders these tsunami records were recently re examined digitized and thoroughly analysed the other 12 tsunami events were recorded using digital high quality instruments with 1 min sampling interval installed on the coast of british columbia b c in 1998 all 16 tsunami events were recorded at tofino on the outer b c coast and some of the tsunamis were recorded at eight or more stations the tide station at tofino has been in operation for 100 years and these recent observations add to the dataset of tsunami events compiled previously by s o wigen 1983 for the period 1906 1980 for each of the tsunami records statistical analysis was carried out to determine essential tsunami characteristics for all events arrival times maximum amplitudes frequencies and wave train structure the analysis of the records indicated that significant background noise at langara a key northern b c tsunami warning station located near the northern end of the queen charlotte islands creates serious problems in detecting tsunami waves that station has now been moved to a new location with better tsunami response the number of tsunami events observed in the past 15 years also justified re establishing a tide gauge at port alberni where large tsunami wave amplitudes were measured in march 1964 the two meteorological events are the first ever recorded on the b c coast also there have been landslide generated tsunami events which although not recorded on any coastal tide gauges demonstrate along with the recent investigation of a historical catastrophic event the significant risk that landslide generated tsunami pose to coastal and inland regions of b c

buried soil organic inclusions in non sorted circles fields in northern sweden age and paleoclimatic context although burial of surface organic soil horizons into deeper mineral soil layers helps drive the long term buildup of carbon in arctic soils when and why buried horizons formed as result of cryotu

waveform and spectral analyses of the 2011 japan tsunami records on tide gauge and dart stations across the pacific ocean we studied the 11 march 2011 tohoku tsunami through analysis of the sea level records from 21 tide gauge and 16 dart deep ocean assessment and reporting of tsunamis stations from across the pacific ocean the extreme power of this trans oceanic tsunami was indicated by the trough to crest heights of 3 03 m at arena cove on the western coast of the usa and 3 94 m at coquimbo on the southern coast of chile the average value of the maximum amplitude was 163 9 cm for the examined tide gauge records at many coastal tide gauge stations the largest wave arrived several hours after the first arrival of the tsunami wave and the tsunami lasted for a long time with an average duration of 4 days on the contrary at most of the dart stations in the deep ocean the first wave was the largest the tsunami amplitudes were smaller with an average maximum of 51 2 cm and the durations were shorter with an average of 2 days the two dominant tsunami periods on the dart records were 37 and 67 4 min which are possibly attributed to the width and length of the tsunami source fault respectively the dimensions of the tsunami source was estimated as 233 km 424 km wavelet analyses of tide gauge and dart records showed that most of the tsunami energy was distributed at the wide period band of around 10 80 min during the first hour after the tsunami arrival then it was concentrated in a relatively narrower band the frequency time plots showed the switches and lapses of tsunami energy at the 35 and 65 min period bands

influence of normal fault growth and linkage on the evolution of a rift basin a case from the gaoyou depression of the subei basin eastern china abstract it is widely acknowledged that the growth and linkage of a boundary fault affects the evolution of the accompanying sedimentary basin and exerts a strong influence on its sedimentary characteristics in this study we attempt to discuss the evolution of a boundary fault and rift basin by using seismic interpretation incremental fault throw and growth rate distance g d profile which are more suitable parameters than the expansion index in rift basins where footwall strata are missing because of erosion or a depositional hiatus therefore the gaoyou depression is taken as an example the gaoyou depression is the largest hydrocarbon bearing depression in the subei basin which is a representative rift basin in eastern china the depression is bounded to the south by the jiangdu wubao fault zone which includes the zhen 1 wu 1 zhen 2 and wu 2 faults using high resolution three dimensional seismic data the zhen 1 wu 1 fault can be subdivided into four segments based on its g d profile the shaobo fanchuan liuwushe and liulu segments growth rates indicate that the zhen 1 wu 1 fault and the zhen 2 and wu 2 faults developed successively from the late cretaceous to the miocene during rifting of the gaoyou depression and that development of the zhen 2 and wu 2 faults was controlled by the zhen 1 wu 1 fault the four segments of the zhen 1 wu 1 fault were linked with each other by the time the zhen 2 and wu 2 faults formed in the late paleocene an evolution model of the gaoyou depression is set up in this study integrating the fault activity with previous sedimentological studies we suggest that the evolution of the gaoyou depression was controlled by the jiangdu wubao fault zone rather than by a single fault successive slip of the zhen 1 wu 1 fault and the zhen 2 and wu 2 faults caused subsidence and migration of the depocenters this study presents a case investigation of the effects of boundary faults on rift basins in eastern china

flint workshop affiliation chronology technology and site formation processes at giv at rabbi east lower galilee israel abstract salvage excavations at the middle paleolithic flint workshop giv at rabi east lower galilee israel aimed at obtaining chronometric ages for the site s exploitation reconstructing the process of its formation and collecting an assemblage of diagnostic flint items for testing the conjectured connection with nearby qafzeh cave the excavations revealed two archaeological units the lower one directly overlaying the calcrete bedrock formation and separated from the upper one by a sterile layer of clay sediments the sequence of four osl ages fall within the time range of the levantine middle paleolithic and correspond to mis 6 and most of mis 5 the assemblage of flint artefacts included hundreds of levallois debitage items alongside bifacial fossiles directeurs of the lower paleolithic acheulian found mostly in the lower archaeological unit while parameters reflecting the degree of core exploitation i e size number of scars and amount of cortex support the hypothesized connection between the workshop and qafzeh cave osl dates suggest that the beginning of the workshop s existence predates that cave s occupation moreover the possibility that the upper archaeological unit in gre represents re deposited part of the original accumulation of flint artefacts reduces even more the likelihood of the connection between the workshop and the cave these results suggest that additional and more remote sites were probably involved in the workshop formation and allow for a variety of scenarios concerning acquisition and management of flint resources during the middle paleolithic in the lower galilee chronometric dates within the sequence of the middle paleolithic the indication of nearly in situ deposition of the lower archaeological unit alongside physical condition of different artefact groups suggest that the bifacial type fossils of the lower paleolithic acheulian may have been recycled by middle paleolithic hominids

paleomagnetic quantification of upper plate deformation during miocene detachment faulting in the mohave mountains arizona 1 paleomagnetic data from miocene 20 ma volcanic rocks and dikes of west central arizona reveal the tilt history of proterozoic crystalline rocks in the hanging wall of the chemehuevi whipple mountains detachment fault we obtained magnetization data from dikes and flows in two structural blocks encompassing crossman peak and standard wash in the mohave mountains in the crossman block the dike swarm records two components of primary magnetization 1 cnh a normal polarity high unblocking temperature or high coercivity component inclination i 48 5 declination d 6 4 and 2 crhm a reversed polarity high temperature or high coercivity component i 33 6 d 197 5 argon age spectra imply that the dikes have not been reheated above 300 c since their emplacement and a baked contact test suggests that the magnetization is likely to be miocene in age crhm deviates from the expected direction of the miocene axial dipole field and is best explained as a result of progressive tilting about the strike of the overlying andesite flows these data suggest that the crossman block was tilted 60 to the southwest prior to intrusion of the vertical dike swarm and the block continued to tilt during a magnetic field reversal to normal polarity cnh miocene dikes in the crossman block are roughly coplanar so the younger dikes with normal polarity magnetization intruded along planes of weakness parallel to the earlier reversed polarity swarm an alternative explanation involves cnh magnetization being acquired later during hydrothermal alteration associated with the final stages of dike emplacement in the standard wash block the primary component of magnetization is a dual polarity high temperature or high coercivity component swhl i 7 2 d 0 7 to produce agreement between the expected miocene magnetic direction and the swh component requires 1 correcting for a 56 tilt about the strike of flow bedding and 2 removing a counterclockwise vertical axis rotation of 20 the two rotations restore the standard wash dikes to vertical make parallel the dike layering in the crossman and standard wash blocks and align the strikes of bedding in both blocks geologic mapping geochemical evidence and paleomagnetic data are consistent with the upper plate of the mohave mountains having tilted in response to formation of the underlying detachment fault

a flying start then a slow slip the human tragedy caused by the sumatra andaman earthquake moment magnitude 9 3 on 26 december 2004 and its companion nias earthquake moment magnitude 8 7 on 28 march 2005 is difficult to comprehend these earthquakes the largest in 40 years have also left seismologists searching for the words and tools to describe the enormity of the geological processes involved four papers in this issue discuss aspects of a rupture process of surprising complexity the first such event to test the sensitivity and range of many new technologies a surprising feature of the earthquake is that after the initial rapid rupture subsequent slip of the plate interface occurred with decreasing speed toward the north