investigating multiple fault rupture at the salar del carmen segment of the atacama fault system northern chile fault scarp morphology and knickpoint analysis this study presents a new geomorphological approach to investigate the past activity and potential seismic hazard of upper crustal faults at the salar del carmen segment of the atacama fault system in the northern chile forearc our contribution is based on the analysis of a large set of topographic profiles and allows extrapolating fault analysis from a few selected locations to distances of kilometers along strike of the fault we detected subtle changes in the fault scarp geometry which may represent the number of paleoearthquakes experienced by the structure and extracted the cumulative and last incremental displacement along strike of the investigated scarps we also tested the potential of knickpoints in channels crossing the fault scarps as markers for repeated fault rupture and proxies for seismic displacement the number of paleoearthquakes derived from our analysis is 2 3 well in agreement with recent paleoseismological investigations which suggest 2 3 earthquakes mw 6 5 6 7 at the studied segments knickpoints record the number of events for about 55 of the analyzed profile pairs only few knickpoints represent the full seismic displacement while most retain only a fraction of the displacement the along strike displacement distributions suggest fault growth from the center toward the tips and linkage of individual ruptures our approach also improves the estimation of paleomagnitudes in case of multiple fault rupture by allowing to quantify the last increment of displacement separately paleomagnitudes calculated from total segment length and the last increment of displacement mw 6 5 7 1 are in agreement with paleoseismological results

lunar global shape and polar topography derived from kaguya lalt laser altimetry a global lunar topographic map with a spatial resolution of finer than 0 5 degree has been derived using data from the laser altimeter lalt on board the japanese lunar explorer selenological and engineering explorer selene or kaguya in comparison with the previous unified lunar control network ulcn 2005 model the new map reveals unbiased lunar topography for scales finer than a few hundred kilometers spherical harmonic analysis of global topographic data for the moon earth mars and venus suggests that isostatic compensation is the prevailing lithospheric support mechanism at large scales however simple rigid support is suggested to dominate for the moon venus and mars for smaller scales which may indicate a drier lithosphere than on earth especially for the moon and venus

global distribution of large lunar craters implications for resurfacing and impactor populations by using high resolution altimetric measurements of the moon we produced a catalog of all impact craters 20 kilometers in diameter on the lunar surface and analyzed their distribution and population characteristics the most densely cratered portion of the highlands reached a state of saturation equilibrium large impact events such as orientale basin locally modified the prebasin crater population to 2 basin radii from the basin center basins such as imbrium orientale and nectaris which are important stratigraphic markers in lunar history are temporally distinguishable on the basis of crater statistics the characteristics of pre and postmare crater populations support the hypothesis that there were two populations of impactors in early solar system history and that the transition occurred near the time of the orientale basin event

climate environment and humans in north america s great basin during the younger dryas 12 900 11 600 calendar years ago global climate change associated with the onset of the younger dryas chronozone affected different regions of the northern hemisphere in different ways in the great basin of western north america the effect was positive for human populations relatively cool temperatures causing effectively wetter conditions filled some pluvial basins with shallow but permanent lakes and other basins with wellwatered marshes or meadows vegetation communities dominated by sagebrush and grasses promoted healthy and diverse animal populations ten archaeological sites from the region have been dated to the younger dryas chronozone evidence from these sites indicates that paleoindians with skull shapes and mitochondrial dna similar to modern western north american indians occupied the region these early humans produced a material culture characterized predominantly by large stemmed bifacial points although one site contained a small fluted point curated tool forms and technological activities represented in analyzed lithic assemblages suggest a highly mobile settlement strategy and redundant short term occupations of sites indicate frequent and long distance residential moves across territories spanning distances of up to 400 km paleoindian subsistence pursuits focused on artiodactyls primarily mule deer bighorn sheep and pronghorn antelope leporids chiefly jackrabbits birds sage grouse and waterfowl insects grasshoppers and possibly fish easy to process plants like cactus pads were also eaten but small seeds do not seem to have been an important part of great basin human diets until long after the younger dryas closer to 9500 cal bp the great basin record contains no evidence for natural catastrophe at the onset of the chronozone instead the younger dryas appears to have been among the best of times for human foragers in this region of north america 2011 elsevier ltd and inqua

the transition from complex craters to multi ring basins on the moon quantitative geometric properties from lunar reconnaissance orbiter lunar orbiter laser altimeter lola data united states national aeronautics and space administration nasa lunar reconnaissance orbiter lunar orbiter laser altimeter lola experiment nnx09am54g

geometric relations of dip slip to a faulted ground surface new nomograms for estimating components of fault displacement abstract the throw heave and dip slip components of displacement on a fault scarp can be estimated from two easily collected field measurements when fault dip is known or assumed the vertical separation and slope angle of the original ground surface displaced across the fault nomograms allow graphical determination of slip components for cases where fault dip is in the same or in an opposite direction as the slope of the ground surface the technique has several advantages over a previous method that requires three field measurements those of scarp height scarp slope angle and the slope of the original ground surface the geometric relations of a fault scarp illustrate that although differences between throw and vertical separation of the ground surface are small in the cases of steep fault dips or flat ground surfaces these differences can be greater than commonly assumed

evidence for paleoseismic slip on a continental low angle normal fault tectonic pseudotachylyte from the west salton detachment fault ca usa abstract the potential of continental low angle normal faults lanf to nucleate large 6 0 m w earthquakes at low angles remains unclear despite much focused research we document evidence for ancient seismicity along a continental lanf detachment fault that formed and slipped at low angles and produced tectonic pseudotachylyte these thick and laterally persistent pseudotachylyte accumulations along the west salton detachment fault wsdf salton trough usa preserve convincing evidence for a frictional melt origin including spherulitic microlites ductile flow structures preservation of high temperature phases as clasts and injection veins cumulative thickness of pseudotachylyte along the fault ranges from 0 1 to 1 5 m and pseudotachylyte cataclasite in the fault core and damage zone are exposed along 2 6 km length of the fault reworked fragments of pseudotachylyte in cataclasites and multiple generations of cataclasites provide evidence for the preservation of multiple earthquake cycles the limited exposure

earthquake processes in the rainbow mountain fairview peak dixie valley nevada region 1954 1959 the 1954 rainbow mountain fairview peak dixie valley nevada sequence produced the most extensive pattern of surface faults in the intermountain region in historic time five earthquakes of m 6 0 occurred during the first 6 months of the sequence including the december 16 1954 fairview peak m 7 1 and dixie valley m 6 8 earthquakes three 5 5 m 6 5 earthquakes occurred in the region in 1959 but none exhibited surface faulting the results of the modeling suggest that the m 6 5 earthquakes of this sequence are complex events best fit by multiple source time functions although the observed surface displacements for the july and august 1954 events showed only dip slip motion the fault plane solutions and waveform modeling suggest the earthquakes had significant components of right lateral strike slip motion rakes of 135 to 145 all of the earthquakes occurred along high angle faults with dips of 40 to 70 seismic moments for individual subevents of the sequence range from 8 0 1017 to 2 5 1019 n m stress drops for the subevents including the fairview peak subevents were between 0 7 and 6 0 mpa

new empirical relationships among magnitude rupture length rupture width rupture area and surface displacement source parameters for historical earthquakes worldwide are compiled to develop a series of empirical relationships among moment magnitude m surface rupture length subsurface rupture length downdip rupture width rupture area and maximum and average displacement per event the resulting data base is a significant update of previous compilations and includes the additional source parameters of seismic moment moment magnitude subsurface rupture length downdip rupture width and average surface displacement each source parameter is classified as reliable or unreliable based on our evaluation of the accuracy of individual values only the reliable source parameters are used in the final analyses in comparing source parameters we note the following trends 1 generally the length of rupture at the surface is equal to 75 of the subsurface rupture length however the ratio of surface rupture length to subsurface rupture length increases with magnitude 2 the average surface displacement per event is about one half the maximum surface displacement per event and 3 the average subsurface displacement on the fault plane is less than the maximum surface displacement but more than the average surface displacement thus for most earthquakes in this data base slip on the fault plane at seismogenic depths is manifested by similar displacements at the surface log linear regressions between earthquake magnitude and surface rupture length subsurface rupture length and rupture area are especially well correlated showing standard deviations of 0 25 to 0 35 magnitude units most relationships are not statistically different at a 95 significance level as a function of the style of faulting thus we consider the regressions for all slip types to be appropriate for most applications regressions between magnitude and displacement magnitude and rupture width and between displacement and rupture length are less well correlated and have larger standard deviation than regressions between magnitude and length or area the large number of data points in most of these regressions and their statistical stability suggest that they are unlikely to change significantly in response to additional data separating the data according to extensional and compressional tectonic environments neither provides statistically different results nor improves the statistical significance of the regressions regressions for cases in which earthquake magnitude is either the independent or the dependent parameter can be used to estimate maximum earthquake magnitudes both for surface faults and for subsurface seismic sources such as blind faults and to estimate the expected surface displacement along a fault for a given size earthquake

shoreline processes and the age of the lake lahontan highstand in the jessup embayment nevada the well developed shoreline record of pluvial lake lahontan in the jessup embayment nevada is used to refine the history of late pleistocene lake level fluctuations and to assess controls on shoreline development and distribution controls on the strength and type of shorelines developed include local slope the amount and characteristics of sediment available for transport the availability of accommodation space and length of time the lake level resides at a particular shoreline elevation at the sehoo highstand and during the early part of the regression strong storm winds and waves from the south southeast set up a clockwise net shore drift pattern near the head of the embayment although significant differences in local slope geometry of the shoreline and wave energy existed in the embayment crestal heights of constructional shoreline features formed at the highstand vary 2 6 m in elevation and hence provide a relatively precise marker of the highstand elevation radiocarbon dating of a camel bone preserved in high shoreline deposits indicates that the lake reached its highest elevation of 1338 5 m in the embayment and receded from that elevation immediately prior to 13 070 60 yr b p similar and slightly older radiocarbon ages on gastropod shells preserved in barrier deposits at 1327 m 13 280 110 yr b p and 1331 m 13 110 110 yr b p suggest that the final rise to the highstand was very rapid and that the lake maintained its highest stand for a very brief period of time perhaps only for years or decades the brevity of the highstand is reasonable in light of the recent formation of similar barrier features in modern pyramid lake which formed in less than seven months due to a rapid increase in lake level

gld100 the near global lunar 100 m raster dtm from lroc wac stereo image data 1 we derived near global lunar topography from stereo image data acquired by the wide angle camera wac of the lunar reconnaissance orbiter camera lroc system from polar orbit tracks the lroc wac provides image data with a mean ground resolution at nadir of 75 m pixel with substantial cross track stereo overlap wac stereo images from the one year nominal mission and the first months of the science mission phase are combined to produce a near global digital terrain model dtm with a pixel spacing of 100 m the global lunar dtm 100 m or gld100 it covers 79 s to 79 n latitudes 98 2 of the entire lunar surface we compare the gld100 with results from previous stereo and altimetry based products particularly with the lunar orbiter laser altimeter lola altimetry which is the current topographic reference for the moon we describe typical characteristics of the gld100 and based upon the comparison to the lola data set assess its vertical and lateral resolution and accuracy we conclude that the introduced first version of the stereo based gld100 is a valuable topographic representation of the lunar surface complementary to the lola altimetry data set further improvements can be expected from continuative investigations

ancient igneous intrusions and early expansion of the moon revealed by grail gravity gradiometry the earliest history of the moon is poorly preserved in the surface geologic record due to the high flux of impactors but aspects of that history may be preserved in subsurface structures application of gravity gradiometry to observations by the gravity recovery and interior laboratory grail mission results in the identification of a population of linear gravity anomalies with lengths of hundreds of kilometers inversion of the gravity anomalies indicates elongated positive density anomalies that are interpreted to be ancient vertical tabular intrusions or dikes formed by magmatism in combination with extension of the lithosphere crosscutting relationships support a pre nectarian to nectarian age preceding the end of the heavy bombardment of the moon the distribution orientation and dimensions of the intrusions indicate a globally isotropic extensional stress state arising from an increase in the moon s radius by 0 6 to 4 9 kilometers early in lunar history consistent with predictions of thermal models

active megadetachment beneath the western united states geodetic data interpreted in light of seismic imaging seismicity xenolith studies and the late quaternary geologic history of the northern great basin suggest that a subcontinental scale extensional detachment is localized near the moho to first order seismic yielding in the upper crust at any given latitude in this region occurs via an m7 earthquake every 100 years here we develop the hypothesis that since 1996 the region has undergone a cycle of strain accumulation and release similar to slow slip events observed on subduction megathrusts but yielding occurred on a subhorizontal surface 5 10 times larger in the slip direction and at temperatures 800 c net slip was variable ranging from 5 to 10 mm over most of the region strain energy with moment magnitude equivalent to an m7 earthquake was released along this megadetachment primarily between 2000 0 and 2005 5 slip initiated in late 1998 to mid 1999 in northeastern nevada and is best expressed in late 2003 during a magma injection event at moho depth beneath the sierra nevada accompanied by more rapid eastward relative displacement across the entire region the event ended in the east at 2004 0 and in the remainder of the network at about 2005 5 strain energy thus appears to have been transmitted from the cordilleran interior toward the plate boundary from high gravitational potential to low via yielding on the megadetachment the size and kinematic function of the proposed structure in light of various proxies for lithospheric thickness imply that the subcrustal lithosphere beneath nevada is a strong thin plate even though it resides in a high heat flow tectonic regime a strong lowermost crust and upper mantle is consistent with patterns of postseismic relaxation in the southern great basin deformation microstructures and low water content in dunite xenoliths in young lavas in central nevada and high temperature microstructures in analog surface exposures of deformed lower crust large scale decoupling between crust and upper mantle is consistent with the broad distribution of strain in the upper crust versus the more localized distribution in the subcrustal lithosphere as inferred by such proxies as low p wave velocity and mafic magmatism

lunar impact basins stratigraphy sequence and ages from superposed impact crater populations measured from lunar orbiter laser altimeter lola data 1 impact basin formation is a fundamental process in the evolution of the moon and records the history of impactors in the early solar system in order to assess the stratigraphy sequence and ages of impact basins and the impactor population as a function of time we have used topography from the lunar orbiter laser altimeter lola on the lunar reconnaissance orbiter lro to measure the superposed impact crater size frequency distributions for 30 lunar basins d 300 km these data generally support the widely used wilhelms sequence of lunar basins although we find significantly higher densities of superposed craters on many lunar basins than derived by wilhelms 50 higher densities our data also provide new insight into the timing of the transition between distinct crater populations characteristic of ancient and young lunar terrains the transition from a lunar impact flux dominated by population 1 to population 2 occurred before the mid nectarian this is before the end of the period of rapid cratering and potentially before the end of the hypothesized late heavy bombardment lola derived crater densities also suggest that many pre nectarian basins such as south pole aitken have been cratered to saturation equilibrium finally both crater counts and stratigraphic observations based on lola data are applicable to specific basin stratigraphic problems of interest for example using these data we suggest that serenitatis is older than nectaris and humboldtianum is younger than crisium sample return missions to specific basins can anchor these measurements to a pre imbrian absolute chronology

late quaternary paleoseismology of the southern steens fault zone northern nevada the 192 km long steens fault zone is the most prominent normal fault system in the northern basin and range province of western north america we use trench mapping and radiometric dating to estimate displacements and timing of the last three surface rupturing earthquakes e1 e3 on the southern part of the fault south of denio nevada coseismic displacements range from 1 1 to 2 2 0 5 m and radiometric ages indicate earthquake times of 11 5 2 0 ka e3 6 1 0 5 ka e2 and 4 6 1 0 ka e1 these data yield recurrence intervals of 5 4 2 1 k y between e3 and e2 1 5 1 1 k y between e2 and e1 and an elapsed time of 4 6 1 0 k y since e1 the recurrence data yield variable interval slip rates between 0 2 0 22 and 1 5 2 3 mm yr but slip rates averaged over the past 18 k y 0 24 0 06 mm year are similar to long term 8 5 12 5 ma slip rates 0 2 0 1 mm yr measured a few kilometers to the north we infer from the lack of significant topographic relief across the fault in bog hot valley that the fault zone is propagating southward and may now be connected with a fault at the northwestern end of the pine forest range displacements documented in the trench and a rupture length of 37 km indicate a history of three latest quaternary earthquakes with magnitudes of m 6 6 7 1 on the southern part of the steens fault zone

coulomb stress evolution in a diffuse plate boundary 1400 years of earthquakes in eastern california and western nevada usa diffuse plate boundaries are characterized by deformation distributed over a wide area in a complex network of active faults and by relatively low strain rates these characteristics make it difficult to understand the spatial and temporal distribution of seismicity the area east of the sierra nevada between longitudes 121 degrees w and 116 degrees w is part of a diffuse plate boundary at least 17 major surface rupturing earthquakes have happened here in the last 1400 years our purpose is to determine whether these events influence each other or whether they are randomly distributed in time and space we model the evolution of coseismic and postseismic coulomb failure stress changes delta cfs produced by these earthquakes and we also model interseismic stresses on the entire fault network our results show that 80 of the earthquake ruptures are located in areas of combined coseismic and postseismic delta cfs 0 2 bar this relationship is robust as shown by the control tests that we carried out using random earthquake sequences we also show that the fish lake valley pyramid lake and honey lake faults have accumulated 45 37 and 27 bars respectively of total delta cfs i e coseismic postseismic interseismic in the last 1400 years such values are comparable to the average stress drop in a major earthquake and these three faults may be therefore close to failure

surface faulting of the 1954 fairview peak ms 7 2 and dixie valley ms 6 8 earthquakes central nevada abstract the 1954 fairview peak earthquake was followed 4 min and 20 sec later by the dixie valley earthquake surface ruptures were distributed among six different faults that define a complex north trending zone 100 km long and over 15 km wide the rupture sequence progressed from south to north the initial event produced a 32 km rupture of right oblique slip along the east dipping fairview fault where the components of right lateral offset and vertical separation reached 2 9 and 3 8 m respectively the northernmost ruptures occurred during the subsequent event along a 46 km portion of the east dipping dixie valley fault where the sense of slip was normal and reached a maximum vertical separation of 2 8 m average surface offset for both events is about 1 2 m the west dipping west gate louderback mountains and gold king faults also ruptured during the earthquake sequence these faults form a complex structural linkage within a 15 km left step that separates the surface traces of the fairview and dixie valley faults the west dipping faults likely played an important role in the redistribution of static stress from the fairview peak earthquake and subsequent triggering of the dixie valley earthquake right lateral offsets of more than a meter occurred along both the west gate and louder back mountains faults slip was limited to normal motion of 1 m or less along the gold king fault the change from right oblique motion along the fairview fault to pure normal motion on the dixie valley fault may reflect the transition from principally northwest extension in the south to more westerly extension in the north alternatively slip at the latitude of the dixie valley fault may be partitioned between pure normal slip along the dixie valley fault and strike slip motion on faults immediately to the west observations of fault dip provide insight to the complex three dimensional geometry of the rupture sequence of particular note a significant section of the dixie valley fault appears to be characterized by dip angles as low as 25 at the surface slip variation or earthquake endpoints do not generally appear to have been influenced by changes in bedrock type we do not observe systematic relations between slip variation and aspects of fault trace geometry such as salients and reentrants yet the relative competence of footwall bedrock appears to have influenced the long term development of large salients and reentrants along both the dixie valley and the fairview faults as well as the style of rupture along the southern portion of the dixie valley fault

geometry of the 1954 fairview peak dixie valley earthquake sequence from a joint inversion of leveling and triangulation data in 1954 four earthquakes greater than ms 6 0 occurred within a 30 km radius and in a period of 6 months elevation and angle changes calculated from repeated leveling and triangulation surveys which span the coseismic period provide constraints on the fault geometries and coseismic slip of the faults which were activated the quality of the coseismic geodetic data is assessed corrections are applied to the leveling data for subsidence due to groundwater withdrawal in the fallon area and a rod miscalibration error of 150 30 ppm is isolated in leveling surveys made in 1967 the leveling and triangulation observations are then simultaneously inverted using the single value decomposition svd inversion method to determine fault geometries and coseismic slip using svd it is possible to determine on which faults slip is resolvable given the data distribution the faults are found to dip between 50 and 80 and extend to depths of 5 to 14 km the geodetically derived slip values are generally equal to or greater than the maximum observed displacement along the surface scarps where slip is resolvable the geodetic data indicates the 1954 sequence contained a significant component of right lateral slip this is consistent with the n15 w trending shear zone which geodetic surveys have detected in western nevada

paleoseismic transect across the northern great basin 1 the relationship of strain accumulation to strain release over different timescales provides insight to the dynamics structural development and spatial and temporal pattern of earthquake recurrence in regions of active tectonics the great basin physiographic province of the western united states is one of the earth s broadest regions of ongoing continental extension encompassing an area reaching 800 km in width between the sierra nevada to the west and wasatch mountains to the east we present observations arising from excavations scarp profiling optically stimulated luminescence and radiocarbon dating to place limits on the late pleistocene paleoseismic history of faults bounding eight ranges across the interior of the northern great basin specifically the shawave hot springs humboldt sonoma shoshone tuscarora dry hills and pequop ranges combining the observations with similar previously published studies within and at the margins of the great basin yields a transect that extends eastward across the basin between the 40th and 41st parallels the sum of observations provides a picture of the patterns and rates of earthquake recurrence over the region during the last 20 45 kyr that may be compared to patterns of contemporary seismicity and recently reported measures of strain accumulation across the area using gps the recurrence rate of large surface rupture paleoearthquakes along ranges at the margins of the great basin is systematically greater than observed along ranges in the interior the pattern is similar to seismological and geodetic measurements that show levels of background seismicity and strain accumulation are also concentrated along the margins of the great basin an east west extension rate across the interior of the great basin on the order of 1 2 mm yr 1 strain rate of 1 nstrain yr 1 over the last 20 45 kyr is estimated by summing the record of paleoseismic displacements across the 400 km breadth of the transect as compared to 2m m yr 1 of strain accumulation indicated by a recently reported analysis of a collinear gps survey the comparison is hindered by significant uncertainties coupled to the geologic rate estimate the transect also crosses the northern limit of the central nevada seismic belt the central nevada seismic belt is defined by a north northeast trending alignment of historical surface rupture earthquakes increased levels of background seismicity and strain accumulation rates greater than observed elsewhere in the interior of the great basin the reported recurrence rate of late pleistocene surface rupture earthquakes within the central nevada seismic belt is also generally greater than observed along our transect the observations when taken together suggest that the characteristics of strain release observed historically within the central nevada seismic belt have been operative over the latest pleistocene and that the apparently greater rates of strain accumulation and release in the central nevada seismic belt are diminished or less localized in regions to the north and east thus while the historical alignment of surface ruptures that defines the central nevada seismic belt remains a unique clustering of earthquakes in time and space the likelihood of the cluster at its observed location appears greater than would be expected to the north or eastward in the interior of the great basin

normal faulting during the august 1989 earthquakes in central afar sequential triggering and propagation of rupture along the dobi graben in august 1989 an earthquake sequence including ten events with 6 3 m 5 5 in the first two days produced widespread ground deformation in the dobi graben of central afar numerous surface breaks with complex geometry including fresh scarplets with vertical throws up to 30 cm high and open fissures up to 30 cm wide were observed coseismic slip incremented the deformation normal faulting block tilting and counterclockwise rotation of basaltic slices accumulated in the last 2 m y in the transfer zone between the dobi and hanle grabens by combining maps of surface ruptures relative event relocations with the local djibouti network published focal mechanisms and source sizes we tentatively relate most of the main shocks of the sequence to slip on individual faults the largest shocks at 11h16 on 20 august 1989 ms 6 2 and at 1h09 on 21 august 1989 ms 6 3 ruptured southern segments of the southwestern bounding fault of the graben a dozen other faults also slipped along the edges of and inside the graben on average triggered seismic fault ing propagated about 35 km northwestward along the graben in about 20 hr slip on the main faults was coupled with slip on secondary antithetic faults branching from them at depth although the dobi earthquakes ruptured part of the fault array between the asal rift 1978 sequence and the serdo region 1969 sequence an approximately 50 km long gap subsists along the der ela half graben we infer the patterns of sur face faulting in the dobi sequence which coinvolved bookshelf faulting about both horizontal and vertical axes to typify the complexity of coseismic stress release in central afar and in other active zones of distributed extension e g iceland abruzzi basin and range online material additional photos and descriptions of surface effects of the dobi earthquake sequence

a new lunar digital elevation model from the lunar orbiter laser altimeter and selene terrain camera abstract we present an improved lunar digital elevation model dem covering latitudes within 60 at a horizontal resolution of 512 pixels per degree 60 m at the equator and a typical vertical accuracy 3 to 4 m this dem is constructed from 4 5 10 9 geodetically accurate topographic heights from the lunar orbiter laser altimeter lola onboard the lunar reconnaissance orbiter to which we co registered 43 200 stereo derived dems each 1 1 from the selene terrain camera tc 1010 pixels total after co registration approximately 90 of the tc dems show root mean square vertical residuals with the lola data of

pattern and rates of faulting in the central nevada seismic belt and paleoseismic evidence for prior beltlike behavior the central nevada seismic belt cnsb is a concentration of historical 1915 1932 1954 surface faulting in the western basin and range province forming a linear nearly continuous 300 km long rupture zone previous results are integrated in this study with new paleoseismic and exploratory trenching data from the historical zones to look for evidence of older similar beltlike patterns or elevated slip rates that could indicate whether the cnsb is a zone of focused long term crustal strain the data show that the continuous rupture belt produced by the seven earthquakes occurring between 1915 and 1954 is unique in the available paleoseismic record at the 1954 fairview peak fault the lack of prehistorical faulting in deposits containing the wilson creek bed 19 tephra eliminates the possibility of an identical seismic belt in the past 35 4 ka our studies also show that the faults have net slip rates ranging from a low of 0 09 mm yr on the fairview peak fault to a high of 0 7 mm yr on the 1932 cedar mountain fault these are considered moderate to low rates that are similar to most late quaternary faults in the western basin and range province a space time comparison shows that the paleoseismic histories for these multiple rupture zones are diverse and the number and timing of events in each of the zones indicate that there is little evidence for older contemporaneous ruptures of these same faults based on these results we reach several conclusions regarding the longer term holocene behavior of the cnsb although paleoseismic data preclude an older identical rupture belt among the historical zones consideration of associated holocene faults within the greater cnsb region indicates that several similar but not identical beltlike rupture patterns are plausible during the past 13 ka although each requires seismic gaps in the along strike pattern although long term strain represented by density of young faults does appear to increase from east to west into the cnsb the slip rate data demonstrate that the cnsb is not a belt of concentrated or elevated crustal strain compared with areas that extend west to the sierra nevada the increase in the distribution of holocene fault activity from east to west into the cnsb is consistent with a marked increase in the 1992 2002 gps velocity field at the latitude of the 1954 rupture sequence however a comparison of the geologic rates across the belt at this same latitude indicates that the extension rates 0 59 1 37 mm yr are systematically lower than both the campaign and continuous gps rates 2 20 3 13 mm yr by factors of 2 5 these discrepancies may be due to postseismic strain or to some form of off fault deformation we conclude that the results of our study of fault behavior in the cnsb best support the belt migration model proposed by wallace 1987 for the western basin and range province in which temporal tectonic pulses are believed to migrate regionally activating different beltlike combinations of late quaternary faults in an as yet unknown pattern of migration

statistical relations among earthquake magnitude surface rupture length and surface fault displacement abstract in order to refine correlations of surface wave magnitude fault rupture length at the ground surface and fault displacement at the surface by including the uncertainties in these variables the existing data were critically reviewed and a new data base was compiled earthquake magnitudes were redetermined as necessary to make them as consistent as possible with the gutenberg methods and results which make up much of the data base measurement errors were estimated for the three variables for 58 moderate to large shallow focus earthquakes regression analyses were then made utilizing the estimated measurement errors the regression analysis demonstrates that the relations among the variables magnitude length and displacement are stochastic in nature the stochastic variance introduced in part by incomplete surface expression of seismogenic faulting variation in shear modulus and regional factors dominates the estimated measurement errors thus it is appropriate to use ordinary least squares for the regression models rather than regression models based upon an underlying deterministic relation in which the variance results primarily from measurement errors significant differences exist in correlations of certain combinations of length displacement and magnitude when events are grouped by fault type or by region including attenuation regions delineated by evernden and others estimates of the magnitude and the standard deviation of the magnitude of a prehistoric or future earthquake associated with a fault can be made by correlating m s with the logarithms of rupture length fault displacement or the product of length and displacement fault rupture area could be reliably estimated for about 20 of the events in the data set regression of m s on rupture area did not result in a marked improvement over regressions that did not involve rupture area because no subduction zone earthquakes are included in this study the reported results do not apply to such zones

understanding kinematics of intra arc transcurrent deformation paleomagnetic evidence from the liquine ofqui fault zone chile 38 41 s the liquine ofqui fault zone lofz is a major 1000 km long dextral shear zone of southern chile likely related to strain partitioning of nazca plate oblique convergence with south america to understand block rotation pattern along the lofz we paleomagnetically sampled 55 sites 553 samples between 38 s and 41 s we gathered oligocene to pleistocene volcanics and miocene granites at a maximum distance of 20 km from the lofz and at both sides of it rotations with respect to south america evaluated for 36 successful sites show that crust around the lofz is fragmented in small blocks 1 to 10 km in size while some blocks at both fault edges undergo very large 150 170 rotations others do not rotate even adjacent to fault walls we infer that rotations affected equidimensional blocks while elongated crust slivers were translated subparallel to the lofz without rotating rotation pattern across the lofz is markedly asymmetric east of the fault and adjacent to it rotations are up to 150 170 clockwise and fade out 10 km east of fault these data support a quasi continuous crust kinematics characterized by small rigid blocks drag by the underlying ductile crust flow and imply 120 km of total fault offset conversely crust west of the lofz is cut by seismically active nw se sinistral antithetic faults and yields counterclockwise rotations up to 170 at 8 10 km from lofz besides the unrotated blocks further data from the chile fore arc are needed to understand block rotation kinematics and plate dynamics west of the lofz

initial observations from the lunar orbiter laser altimeter lola as of june 19 2010 the lunar orbiter laser altimeter an instrument on the lunar reconnaissance orbiter has collected over 2 0 10 9 measurements of elevation that collectively represent the highest resolution global model of lunar topography yet produced these altimetric observations have been used to improve the lunar geodetic grid to 10 m radial and 100 m spatial accuracy with respect to the moon s center of mass lola has also provided the highest resolution global maps yet produced of slopes roughness and the 1064 nm reflectance of the lunar surface regional topography of the lunar polar regions allows precise characterization of present and past illumination conditions lola s initial global data sets as well as the first high resolution digital elevation models dems of polar topography are described herein

historic surface faulting and paleoseismicity in the area of the 1954 rainbow mountain stillwater earthquake sequence central nevada the rainbow mountain area was the site of three surface rupturing earthquakes on 6 july and 23 august 1954 more than 50 field measurements of surface offsets constrain the distribution of slip along the discontinuous and distrib uted rupture zone that formed during the earthquake sequence vertical offsets reach a maximum of 0 8 m with the average vertical offset being 0 2 m in contrast to original reports we see evidence for a right lateral component of slip along portions of the rupture zone including offset stream channels 0 5 1 0 m left stepping en echelon scarps and a well preserved 100 m long mole track the right slip com ponent is consistent with focal plane solutions for the events and recent geodetic results previously unmapped surface ruptures now extend the known rupture length of the sequence by 25 km to a total of 70 km surface ruptures along the previously unmapped fourmile flat fault are subparallel to and form a 10 km left step to the southeast of the rainbow mountain fault event locations and anecdotal information indicate that the fourmile flat ruptures represent minor primary surface rupture associated with the large 6 july aftershock triggered 11 hr after the initial 6 july rainbow mountain event the paleoseismic histories of the rainbow mountain and fourmile flat faults as recorded in natural and trench exposures are different although both faults experi enced three post 15 ka surface rupturing events including 1954 bracketing ages for triultimate events on both faults do not overlap however constraints on the penultimate event for the rainbow mountain and triultimate event for the fourmile flat fault do overlap slightly allowing the possibility that they may have ruptured close in time as in 1954 the holocene slip rate for the fourmile flat fault 0 40 mm yr is similar to the post latest pleistocene rate for the rainbow mountain fault 0 20 0 46 mm yr even though the total length of the fourmile flat 10 km is much shorter than the overall length of the rainbow mountain rupture zone 60 km indicating that even minor faults can be important for assessing regional strain rates and patterns

long term fault slip rates distributed deformation rates and forecast of seismicity in the western united states from joint fitting of community geologic geodetic and stress direction data sets 1 the long term average velocity field of the western united states is computed with a kinematic finite element code community data sets include fault traces geologic offset rates geodetic velocities principal stress directions and euler poles there is an irreducible minimum amount of distributed permanent deformation which accommodates one third of pacific north america relative motion in california much of this may be due to slip on faults not included in the model all data sets are fit at a common rms level of 1 8 datum standard deviations experiments with alternate weights fault sets and euler poles define a suite of acceptable community models in pseudoprospective tests fault offset rates are compared to 126 additional published rates not used in the computation 44 are consistent another 48 have discrepancies under 1 mm a 1 and 8 have larger discrepancies updated models are then computed novel predictions include dextral slip at 2 3 mm a 1 in the brothers fault zone two alternative solutions for the mendocino triple junction slower slip on some trains of the san andreas fault than in recent hazard models and clockwise rotation of some domains in the eastern california shear zone long term seismicity is computed by assigning each fault and finite element the seismicity parameters coupled thickness corner magnitude and spectral slope of the most comparable type of plate boundary this long term seismicity forecast is retrospectively compared to instrumental seismicity the western united states has been 37 below its long term average seismicity during 1977 2008 primarily because of temporary reduced activity in the cascadia subduction zone and san andreas fault system

lake level variation in the lahontan basin for the past 50 000 years selected radiocarbon data on surficial materials from the lahontan basin nevada and california provide a chronology of lake level variation for the past 50 000 yr a moderate sized lake connected three western lahontan subbasins the smoke creek black rock desert subbasin the pyramid lake subbasin and the winnemucca dry lake subbasin from about 45 000 to 16 500 yr b p between 50 000 and 45 000 yr b p walker lake rose to its sill level in adrian valley and spilled to the carson desert subbasin by 20 000 yr b p lake level in the western lahontan subbasins had risen to about 1265 m above sea level where it remained for 3500 yr by 16 000 yr b p lake level in the western lahontan subbasins had fallen to 1240 m this recession appears synchronous with a desiccation of walker lake however whether the walker lake desiccation resulted from climate change or from diversion of the walker river is not known from about 15 000 to 13 500 yr b p lake level rapidly rose so that lake lahontan was a single body of water by 14 000 yr b p the lake appears to have reached a maximum highstand altitude of 1330 m by 13 500 yr b p a condition that persisted until about 12 500 yr b p at which time lake level fell 100 m no data exist that indicate the level of lakes in the various subbasins between 12 000 and 10 000 yr b p during the holocene the lahontan basin was the site of shallow lakes with many subbasins being the site of one or more periods of desiccation the shape of the lake level curve for the three western subbasins indicates that past changes in the hydrologic balance and hence climate of the lahontan basin were large in magnitude and took place in a rapid step like manner the rapid changes in lake level are hypothesized to have resulted from changes in the mean position of the jet stream as it was forced north or south by the changing size and shape of the continental ice sheet

surface faulting and paleoseismic history of the 1932 cedar mountain earthquake area west central nevada and implications for modern tectonics of the walker lane the 1932 cedar mountain earthquake m s 7 2 was one of the largest historical events in the walker lane region of western nevada and it produced a complicated strike slip rupture pattern on multiple quaternary faults distributed through three valleys primary right lateral surface ruptures occurred on north striking faults in monte cristo valley small scale lateral and normal offsets occurred in stewart valley and secondary normal faulting occurred on north northeast striking faults in the gabbs valley epicentral region a reexamination of the surface ruptures provides new displacement and fault zone data maximum cumulative offset is estimated to be 2 7 m and newly recognized faults extend the maximum width and end to end length of the rupture zone to 17 and 75 km respectively a detailed quaternary allostratigraphic chronology based on regional alluvial geomorphic relationships tephrochronology and radiocarbon dating provides a framework for interpreting the paleoseismic history of the fault zone a late wisconsinan alluvial fan and piedmont unit containing a 32 36 ka tephra layer is a key stratigraphic datum for paleoseismic measurements exploratory trenching and radiocarbon dating of tectonic stratigraphy provide the first estimates for timing of late quaternary faulting along the cedar mountain fault zone three trenches display evidence for six faulting events including that in 1932 during the past 32 36 ka radiocarbon dating of organic soils interstratified with tectonically ponded silts establishes best fit ages of the pre 1932 events at 4 5 12 15 and 18 ka each with 2 ka uncertainties on the basis of an estimated cumulative net slip of 6 12 m for the six faulting events minimum and maximum late quaternary slip rates are 0 2 and 0 7 mm yr respectively and the preferred rate is 0 4 0 5 mm yr the average recurrence interseismic interval is 3600 yr the relatively uniform thickness of the ponded deposits suggests that similar size characteristic rupture events may characterize late quaternary slip on the zone a comparison of event timing with the average late quaternary recurrence interval indicates that slip has been largely regular periodic rather than temporally clustered to account for the spatial separation of the primary surface faulting in monte cristo valley from the epicenter and for a factor of two to three disparity between the instrumentally and geologically determined seismic moments associated with the earthquake we hypothesize two alternative tectonic models containing undetected subevents either model would adequately account for the observed faulting on the basis of wrench fault kinematics that may be associated with the walker lane the 1932 cedar mountain earthquake is considered an important modern analogue for seismotectonic modeling and estimating seismic hazard in the walker lane region in contrast to most other historical events in the basin and range province the 1932 event did not occur along a major range bounding fault and no single throughgoing basement structure can account for the observed rupture pattern the 1932 faulting supports the concept that major earthquakes in the basin and range province can exhibit complicated distributive rupture patterns and that slip rate may not be a reliable criterion for modeling seismic hazard

postseismic mantle relaxation in the central nevada seismic belt holocene acceleration of deformation and postseismic relaxation are two hypotheses to explain the present day deformation in the central nevada seismic belt cnsb discriminating between these two mechanisms is critical for understanding the dynamics and seismic potential of the basin and range province interferometric synthetic aperture radar detected a broad area of uplift 2 to 3 millimeters per year that can be explained by postseismic mantle relaxation after a sequence of large crustal earthquakes from 1915 to 1954 the results lead to a broad agreement between geologic and geodetic strain indicators and support a model of a rigid basin and range between the cnsb and the wasatch fault

laser ranging to the lost lunokhod 1 reflector abstract in 1970 the soviet lunokhod 1 rover delivered a french built laser reflector to the moon although a few range measurements were made within three months of its landing these measurements and any that may have followed are unpublished and unavailable the lunokhod 1 reflector was therefore effectively lost until march of 2010 when images from the lunar reconnaissance orbiter lro provided a positive identification of the rover and determined its coordinates with uncertainties of about 100 m this allowed the apache point observatory lunar laser ranging operation apollo to quickly acquire a laser signal the reflector appears to be in excellent condition delivering a signal roughly four times stronger than its twin reflector on the lunokhod 2 rover the lunokhod 1 reflector is especially valuable for science because it is closer to the moon s limb than any of the other reflectors and unlike the lunokhod 2 reflector we find that it is usable during the lunar day we report the selenographic position of the reflector to few centimeter accuracy comment on the health of the reflector and illustrate the value of this reflector for achieving science goals

late pleistocene regional extension rate derived from earthquake geology of late quaternary faults across the great basin nevada between 38 5 n and 40 n latitude maps showing quaternary deposits and active fault traces paleoseismic trenches scarp diffusion analyses and soil characteristics in displaced alluvial surfaces are combined with previous paleoseismic studies to examine the character of late pleistocene earthquake recurrence and estimate the net extension rate across the interior of the great basin of the western united states at the latitude of 39 n the study area includes faults bounding the desatoya toiyabe monitor simpson park toquima antelope fish creek butte egan and schell creek ranges the rate of earthquake recurrence is documented to be significantly less than observed within the walker lane central nevada seismic belt and along the wasatch which respectively define the western and eastern boundaries of the interior of the great basin late pleistocene extension across the interior of the great basin is calculated to equal 1 mm yr across the 450 km transect and is consistent with rates defined by recent geodetic studies the agreement in extension rate estimates over different time scales indicates that tectonic deformation in the great basin has been characterized by relatively slow and consistent extension through the late pleistocene to the present the internal deformation of the great basin and the pattern of strain release may reflect a broad transition zone from northwest directed shear in the west to extension along the eastern edge of the pacific north american plate boundary

gravity study through the tualatin mountains oregon understanding crustal structure and earthquake hazards in the portland urban area a high resolution gravity survey through the tualatin mountains port land hills west of downtown portland exhibits evidence of faults previously iden tified from surface geologic and aeromagnetic mapping the gravity survey was conducted in 1996 along the 4 5 km length of a twin bore tunnel then under con struction and now providing light rail service between downtown portland and com munities west of the portland hills gravitational attraction gradually increases from west to east inside the tunnel which reflects the tunnel s location between low density sedimentary deposits of the tualatin basin to the west and high density mostly concealed eocene basalt to the east superimposed on this gradient are several steplike anomalies that we interpret as evidence for faulted contacts between rocks of contrasting density the largest of these anomalies occurs beneath sylvan creek where a fault had previously been mapped inside the tunnel another occurs 1200 m from the west portal at the approximate intersection of the tunnel with an aeromag netic anomaly associated with the sylvan fault formerly called the oatfield fault lithologic cross sections based on these gravity data show that the steplike anomalies are consistent with steeply dipping reverse faults although strike slip displacements also may be important three gravity lows correspond with topographic lows directly overhead and may reflect zones of shearing several moderate earthquakes m 3 5 occurred near the present day location of the tunnel in 1991 suggesting that some of these faults or other faults in the portland hills fault zone are seismically active