holocene fault scarps near tacoma washington usa airborne laser mapping confirms that holocene active faults traverse the puget sound metropolitan area northwestern continental united states the mapping which detects forest floor relief of as little as 15 cm reveals scarps along geophysical lineaments that separate areas of holocene uplift and subsidence along one such line of scarps we found that a fault warped the ground surface between a d 770 and 1160 this reverse fault which projects through tacoma washington bounds the southern and western sides of the seattle uplift the northern flank of the seattle uplift is bounded by a reverse fault beneath seattle that broke in a d 900 930 observations of tectonic scarps along the tacoma fault demonstrate that active faulting with associated surface rupture and ground motions pose a significant hazard in the puget sound region

mapping crustal stress and strain in southwest british columbia 1 this paper investigates the orientation and sources of stress in the forearc of the cascadia subduction zone in southwest british columbia using bayesian inversion results from focal mechanism data and comparing results with gps derived short term strain rates the subduction margin in this region includes a change in orientation from n s in washington state to nw se in british columbia over 1000 focal mechanisms from north american crustal earthquakes have been calculated to identify the dominant style of faulting and 600 were inverted to estimate the principal stress orientations and the stress ratio our results indicate the maximum horizontal compressive stress orientation changes with distance to the trench from approximately margin normal along the coast to approximately margin parallel 100 150 km inland from the coast comparing stress orientations with gps data we relate the margin normal stress direction to subduction related strain rates due to the locked interface between the north american and juan de fuca plates just west of vancouver island further from the margin the plates are coupled less strongly and the margin parallel maximum horizontal compressive stress in the north american plate relates to the northward push of the oregon block which is also observed in the horizontal shortening direction of the residual strain rates after the subduction component is removed

constraints on the late thermotectonic evolution of the western alps evidence for episodic rapid uplift forty two new apatite and zircon fission track ages are presented for samples from the western alps in southern switzerland northern italy and southeastern france measured ages plotted against assumed closure temperatures yield cooling patterns for the final cooling uplift and exhumation of the western alps similar fission track zircon ages in the penninic gran paradiso massif dent blanche nappe sesia lanzo zone and ivrea zone indicate cooling of all four units to 225 c by 33 ma differences in apatite ages reveal differential cooling of the four blocks between 33 ma and the present in the sesia lanzo zone similarity of apatite ages regardless of elevation together with near volcanic confined fission track length patterns suggest rapid cooling and uplift at 25 ma compared with slow cooling of other western alps units around 12 ma uplift is thus not continuous but episodic often over a short time interval beyond the resolution of other methods such episodes of uplift as revealed here in the sesia lanzo zone may be the rule rather than the exception

location structure and seismicity of the seattle fault zone washington evidence from aeromagnetic anomalies geologic mapping and seismic reflection data a high resolution aeromagnetic survey of the puget lowland shows details of the seattle fault zone an active but largely concealed east trending zone of reverse faulting at the southern margin of the seattle basin three elongate east trending magnetic anomalies are associated with north dipping tertiary strata exposed in the hanging wall the magnetic anomalies indicate where these strata continue beneath glacial deposits the northernmost anomaly a narrow elongate magnetic high precisely correlates with magnetic miocene volcanic conglomerate the middle anomaly a broad magnetic low correlates with thick nonmagnetic eocene and oligocene marine and fluvial strata the southern anomaly a broad complex magnetic high correlates with eocene volcanic and sedimentary rocks this tripartite package of anomalies is especially clear over bainbridge island west of seattle and over the region east of lake washington although attenuated in the intervening region the pattern can be correlated with the mapped strike of beds following a northwest striking anticline beneath seattle the aeromagnetic and geologic data define three main strands of the seattle fault zone identified in marine seismic reflection profiles to be subparallel to mapped bedrock trends over a distance of 50 km the locus of faulting coincides with a diffuse zone of shallow crustal seismicity and the region of uplift produced by the m 7 seattle earthquake of a d 900 930

kinematic analysis of the san juan thrust system washington shear related fabric in the middle to late cretaceous san juan thrust system washington is observed in imbricated blocks and in fault zones a few millimeters to tens of meters thick foliation and lineation are defined in tectonic blocks by alignment of 1 newly grown muscovite and chlorite and 2 flattened and stretched radiolaria mineral porphyroclasts and rock fragments thin argillaceous shear zones bear a pronounced lineation defined by lithologic streaks and slickenside corrugations the slickenside and stretching lineations show a well defined preferred orientation in a horizontal northwest southeast direction widespread s c fabrics asymmetric pressure shadows fault drag features and asymmetric folds in the x z plane yield a sense of tectonic transport at most localities of upper plate to the northwest aragonite prehnite lawsonite pumpellyite and rare na amphibolite and na pyroxene characterize the metamorphism during the thrusting the findings of this study indicate north west orogen parallel transport of the san juan thrust system we suggest that this structure is a large step over zone transferring dextral strike slip from the western cascades to the oceanward side of wrangellia

streaks multiplets and holes high resolution spatio temporal behavior of parkfield seismicity 1 double difference locations of 8000 earthquakes from 1969 2002 on the parkfield section of the san andreas fault reveal detailed fault structures and seismicity that is although complex highly organized in both space and time distinctive features of the seismicity include 1 multiple recurrence of earthquakes of the same size at precisely the same location on the fault multiplets implying frictional or geometric controls on their location and size 2 sub horizontal alignments of hypocenters along the fault plane streaks suggestive of rheological transitions within the fault zone and or stress concentrations between locked and creeping areas 3 regions devoid of microearthquakes with typical dimensions of 1 5 km holes one of which contains the m6 1966 parkfield earthquake hypocenter these features represent long lived structures that persist through many cycles of individual events

upper crustal structure of southwestern british columbia from the 1998 seismic hazards investigation in puget sound 1 this paper applies nonlinear three dimensional travel time tomography to refraction data recorded during the 1998 seismic hazards investigation in puget sound ships to derive the first large scale high resolution upper crustal velocity model for southwestern british columbia a minimum structure p wave velocity model is constructed using 175 000 first arrival travel times picked from data recorded by 58 temporary onshore stations the model details forearc crustal structures related to terrane accretion and subsequent basin formation to a depth of about 10 km the metchosin igneous complex correlative with the eocene crescent siletz terrane in washington is imaged as a laterally extensive wnw trending high velocity anomaly underlying southernmost vancouver island and much of the strait of juan du fuca northeast of the strait of georgia the southwesterly dip of the contact between the wrangellia terrane rocks of vancouver island and the coast plutonic complex suggests wrangellia rocks are down faulted against the plutonic complex at the southwestern end of the strait of juan de fuca the 50 km long wnw trending clallam basin has a maximum thickness of 5 6 km near the eastern end of the strait of juan de fuca port townsend basin has an inferred thickness of approximately 4 5 km the southern end of the 9 km thick georgia basin is bounded by a high velocity basement ridge beneath the strait of georgia clusters of well located earthquakes have a prominent nw trend and coincide spatially with rapid lateral velocity changes clusters of microearthquakes there are associated with the intersection of several east trending structural highs within this nw trend

the effect of velocity structure errors on double difference earthquake location 1 we show that relative earthquake location using double difference methods requires an accurate knowledge of the velocity structure throughout the study region to prevent artifacts in the relative position of hypocenters the velocity structure determines the ray paths between hypocenters and receivers these ray paths and the corresponding ray take off angles at the hypocenters determine the partial derivatives of travel time with respect to the hypocentral coordinates which form the inversion kernel that maps double differences into hypocentral perturbations thus the large scale velocity structure enters into the core of the double difference technique by employing a 1d layered model with sharp interfaces to perform double difference inversion of synthetic data generated using a simple 1d gradient model we show that inappropriate choice of the velocity model combined with unbalanced source receiver distributions can lead to significant distortion and bias in the relative hypocenter positions of closely spaced events

seismicity in cascadia abstract we examine spatio geometric patterns in the density of seismicity within the cascadia forearc to gain insight into controls on seismogenesis tremor epicenters exhibit the most regular distribution defining a 40 80 km wide band extending along almost the entire convergent margin from the southern terminus of gorda plate subduction in northern california to the central explorer plate below northern vancouver island based on prior characterization of constituent low frequency earthquakes the up and down dip limits of tremor are assumed to represent slab isodepth contours at nominal values of 28 and 45 km between which fluids at near lithostatic overpressures are trapped within the subducting slab epicenters of earthquakes within the north american crust are anticorrelated with those of tremor and concentrated in washington and northern california where they are sandwiched between tremor and the cascade volcanic arc seismicity within the subducting plate possesses the most limited epicentral distribution seismicity is confined to shallow depths off vancouver island and in northern california and projects to greater depths beneath washington and southern british columbia comparison of seismicity patterns with long wavelength slab geometry and thermo petrologic constraints suggests that seismicity occurrence in cascadia is governed by an interplay between slab strain metamorphic dehydration within the subducting oceanic plate and a plate boundary seal that controls where fluids enter the overriding plate the inferred fluid evolution model harbors interesting implications for mantle wedge hydrology forearc crustal composition and volcanism in cascadia and other warm subduction zones

lithoprobe southern vancouver island cenozoic subduction complex imaged by deep seismic reflections reply the lithoprobe seismic reflection project on vancouver island was designed to study the large scale structure of several accreted terranes exposed on the island and to determine the geometry and structural characteristics of the subducting juan de fuca plate in this paper we interpret two lithoprobe profiles from southernmost vancouver island that were shot across three important terrane bounding faults leech river san juan and survey mountain to determine their subsurface geometry and relationship to deeper structures associated with modem subduction the structure beneath the island can be divided into an upper crustal region consisting of several accreted terranes and a deeper region that represents a landward extension of the modern offshore subduction complex in the upper region the survey mountain and leech river faults are imaged as northeast dipping thrusts that separate wrangellia a large mesozoic paleozoic terrane from two smaller accreted terranes the leech river schist mesozoic rock

recent movements of the juan de fuca plate system analysis of the magnetic anomalies of the juan de fuca plate system allows instantaneous poles of rotation relative to the pacific plate to be calculated from 7 ma to the present by combining these with global solutions for pacific america and absolute relative to hot spot motions a plate motion sequence can be constructed this sequence shows that both absolute motions and motions relative to america are characterized by slower velocities where younger and more buoyant material enters the convergence zone pivoting subduction the resistance provided by the youngest portion of the juan de fuca plate apparently resulted in its detachment at 4 ma as the independent explorer plate in relation to the hot spot framework this plate almost immediately began to rotate clockwise around a pole close to itself such that its translational movement into the mantle virtually ceased after 4 ma the remainder of the juan de fuca plate adjusted its motion in response to the fact that the youngest material entering the subduction zone was now to the south differences in seismicity and recent uplift between northern and southern vancouver island may reflect a distinction in tectonic style between the normal subduction of the juan de fuca plate to the south and a complex underplating occurring as the explorer plate is overridden by the continent the history of the explorer plate may exemplify the conditions under which the self driving forces of small subducting plates are overcome by the influence of larger adjacent plates the recent rapid migration of the absolute pole of rotation of the juan de fuca plate toward the plate suggests that it too may be nearing this condition

deformation and metamorphism at the south margin of the alps east of bellinzona switzerland deformation and metamorphism of rock series at the south margin of the alps e of bellinzona are studied magmatic relics and metamorphic minerals and rock types of the tonalite and of the augengneiss of melirolo are examined these bodies are regarded as of magmatic origin zoning of plagioclase is ascribed to rise of melts and cooling under loss of volatiles subvolcanic dykes branch off the augengneiss into the tonale series the magmatics are late alpine and intruded into the southerly cover plate on top of the subduction zone the cover plate was still cold and unaffected by alpine deformation during this intrusion later deformation and heating of cover plate and magmatics is late alpine the tonalite deformation was quantified by a study of xenolith deformation the tonalite was flattened to 1 20 of its original width we extrapolate this flattening to the southerly steep zone now 5 km broad we conclude that this zone was 100 km wide befor late alpine flattening this deformation occurred during the higher t part of lepontine heat rise a maximum t of ca 580 c and ph20 5 6 kbar is reached after the main deformation considerable stretching upward buried the niveau of intrusion formerly shallow under 15 20 km of rocks the tonale series suffered 3 fold rotational refolding under subsiding t after the main deformation an early alpine subduction eclogite was found imbricated into the tonale series it still contains parts of the subduction paragenesis preserved or pseudomorphosed and relics of subduction preferred orientation under late alpine deformation it is changed into amphibolite this proves continuation of subduction from val sesia to our area and further e the magmatics are interpreted as subduction magmatites they cannot be derived as partial melts from the subducted slice which underlies the tonale series from which the eclogite was imbricated into the tonale series during late alpine movements voll has found a more northerly subduction zone adula nappe misox zone this may have reached our area in sufficient depth to produce partial melts before late alpine flattening of the marginal zone last movements at the insubric line formed blastomylonites at 300 c indicating vertical movements in our area lepontine garnet staurolite kyanite schists abut directly against the insubric line and the seealpen lower t areas towards the s are cut off by the insubric line

southern california hypocenter relocation with waveform cross correlation part 1 results using the double difference method we present the results of relocating 327 000 southern california earthquakes that occurred between 1984 and 2002 we apply time domain waveform cross correlation for p and s waves between each event and 100 neighboring events identified from the catalog based on a 3d velocity model to simplify the computation we first divide southern california into five polygons such that there are 100 000 events or less in each region the polygon boundaries are chosen to lie in regions of sparse seismicity we calculate and save differential times from the peaks in the cross correlation functions and use a spline interpolation method to achieve a nominal timing precision of 0 001 sec these differential times together with existing p and s phase picks are input to the double difference program of waldhauser and ellsworth 2000 2002 to calculate refined hypocenters we divide the southern california region into grid cells and successively relocate hypocenters within each grid cell the overall resulting pattern of seismicity is more focused than the previously determined pattern from 1d or 3d models the new improved locations are more clustered in many cases by a factor of two or three and often show clear linear alignments in particular the depth distribution is improved and less affected by layer boundaries in velocity models or other similar artifacts

forearc structure beneath southwestern british columbia a three dimensional tomographic velocity model 1 this paper presents a three dimensional compressional wave velocity model of the forearc crust and upper mantle and the subducting juan de fuca plate beneath southwestern british columbia and the adjoining straits of georgia and juan de fuca the velocity model was constructed through joint tomographic inversion of 50 000 first arrival times from earthquakes and active seismic sources wrangellia rocks of the accreted paleozoic and mesozoic island arc assemblage underlying southern vancouver island in the cascadia forearc are imaged at some locations with higher than average lower crustal velocities of 6 5 7 2 km s similar to observations at other island arc terranes the mafic eocene crescent terrane thrust landward beneath southern vancouver island exhibits crustal velocities in the range of 6 0 6 7 km s and is inferred to extend to a depth of more than 20 km the cenozoic olympic subduction complex an accretionary prism thrust beneath the crescent terrane in the olympic peninsula is imaged as a low velocity wedge to depths of at least 20 km three zones with velocities of 7 0 7 5 km s inferred to be mafic and or ultramafic units lie above the subducting juan de fuca plate at depths of 25 35 km the forearc upper mantle wedge beneath southeastern vancouver island and the strait of georgia exhibits low velocities of 7 2 7 5 km s inferred to correspond to 20 serpentinization of mantle peridotites and consistent with similar observations in other warm subduction zones estimated dip of the juan de fuca plate beneath southern vancouver island is 11 16 and 27 at depths of 30 40 and 50 km respectively

identifying active structures using double difference earthquake relocations in southwest british columbia and the san juan islands washington this paper applies double difference earthquake relocation techniques to investigate sources of seismicity in southwest british columbia canada and the san juan islands washington the study area is a complex region of deformation and has the potential for large earthquakes in the north americancrust double difference earthquake relocation techniques are applied to identify otherwise hidden active struc tures that may pose a hazard to nearby population and infrastructure we present evi dence for previously unrecognized active structures using precise relative earthquake relocations obtained using both catalog and waveform cross correlation data results have significantly reduced errors over routine catalog locations and show lineations in areas of clustered seismicity in southwest british columbia these lineations or streaks appear to be hidden structures that do not disrupt near surface sediments however in thesanjuanislandstheidentifiedlineationcouldberelatedtorecentlymappedsurface expressions offaults identifiedfromseismic reflection andmultibeam bathymetric sur veys we use avariety of velocity models for therelocations and find that inappropriate models lead to artifacts at layer boundaries and increased vertical errors

earthquake ground motion and 3d georgia basin amplification in southwest british columbia shallow blind thrust scenario earthquakes abstract finite difference modeling of 3d long period 2 s ground motions for large m w 6 8 scenario earthquakes is conducted to investigate the effects of the georgia basin structure on ground shaking in greater vancouver british columbia canada scenario earthquakes include shallow blind thrust north america na plate earthquakes simulated in locations congruent with linear clusters of shallow seismicity that is potential active faults a slip distribution model of the m w 6 7 northridge california blind thrust earthquake with the hypocenter modified to 5 km depth is used to characterize the source rupture process two sets of simulations are performed for a given scenario earthquake using models with and without georgia basin sediments the ratio of predicted peak ground velocity pgv for the two simulations is applied here as a quantitative measure of amplification due to 3d basin structure a total of eight shallow blind thrust na plate scenario earthquakes are simulated within 100 km of greater vancouver overall predicted ground motions are higher in the down dip direction of each epicenter due to the source radiation pattern hence scenario earthquakes located south of vancouver produce the highest motions in the city the average maximum pgv at stiff soil sites across greater vancouver considering all eight scenario earthquakes is 17 8 cm s modified mercalli intensity vii the average increase in peak motion due to the presence of georgia basin sediments is a factor of 4 1 the effective duration of moderate level 3 4 cm s shaking within greater vancouver is an average of 22 s longer when georgia basin sediments are included in the 3d structure model online material snapshots and videos of wave propagation and peak ground velocity maps

field laboratory and modeling investigation of the skin effect at wells with slotted casing boise hydrogeophysical research site understanding and quantification of wellbore skin improves our ability to accurately measure or estimate hydrologic parameters with tests at wells such as pumping tests flowmeter tests and slug tests this paper presents observations and results from a series of field laboratory and modeling tests which together explain the source of wellbore skin at wells at a research wellfield and which support estimation of skin thickness ds and skin hydraulic conductivity ks positive wellbore skin effects were recognized at wells in the shallow unconfined coarse grained fluvial aquifer at the boise hydrogeophysical research site bhrs well development efforts at the bhrs removed residual drilling fines but only marginally reduced the skin effect likely causes for the remaining wellbore skin effect were examined partial clogging of screen slots with sand is consistent with field observations and can account for the magnitude of wellbore skin effect observed we then use the wtaq code barlow and moench 1999 with a redefinition of the term for delayed observation well response to include skin effects at observation wells in addition to pumping wells in order to analyze aquifer tests at the bhrs for average ks values at individual wells systematic differences in ks values are recognized in results at pumping ks q and observation ks obs wells larger values are seen at observation wells average ks obsz0 0023 cm s than pumping wells two possible causes are recognized for the occurrence of higher ks values at observation wells than pumping wells 1 flow diversion between aquifer layers on approach to a pumping well with positive skin and 2 larger portion offlow passing through lower k zones in the heterogeneous aquifer near the pumping well than the observation wells due to strongly radially convergent flow near the pumping well for the wellaquifer system at the bhrs modeling analyses of drawdown vs time at observation wells provide better ks estimates than those from pumping wells q 2005 elsevier b v all rights reserved

thrust tectonics deep structure and crustal subduction in the alps and himalayas the structural restoration of collision orogenic belts onto crustal templates provides important insights into the tectonic evolution deep structure and amounts of plate convergence after the initial contact between two continental masses balanced cross sections have been constructed parallel to the local displacement directions across the western alps and western himalayas and demonstrate very large amounts of crustal shortening above intra crustal detachments to achieve a balance substantial volumes of lower crust must have been subducted beneath the two tectonic hinterlands a model of eclogite metamorphism is invoked to facilitate this subduction and to explain the varying isostatic responses of the alpine and himalayan hinterlands patterns of eclogite metamorphism are controlled by the geometry of thrust profiles on a lithospheric scale the development of crust mantle detachments being of crucial importance such a profile is proposed for the himalayas suggesting that relatively small volumes of the footwall crust succumbed to eclogite metamorphism in the alps however a steeper thrust profile apparently developed emplacing mantle onto crust causing wholescale eclogite metamorphism in the underlying franco swiss crust the resultant density increase would provide a mechanism of isostatic collapse and flexural subsidence in the po plain region

probabilistic seismic hazard analysis of victoria british columbia considering an active fault zone in the nearby leech river valleyprobabilistic seismic hazard analysis of victoria british columbia

recognizing and modeling variable drawdown due to evapotranspiration in a semiarid riparian zone considering local differences in vegetation and distance from a river source 1 riparian zones in semiarid regions often exhibit high rates of evapotranspiration et in spite of low soil moisture content due to the presence of phreatophytic vegetation that is able to withdraw water from shallow aquifers this work seeks to better define the relationship between et the saturated zone and the river boundary by comparing observed water table drawdown records to analytically modeled drawdown in fully penetrating wells of an unconfined aquifer in response to daily et flux et at the boise hydrogeophysical research site bhrs a riparian zone in a temperate semiarid environment is calculated using a radiation based method to provide et values at four different wells with different vegetation densities analytically modeled drawdown response to et forcing shows that drawdown magnitude increases with increasing distance from the river edge even as the surficial et forcing remains constant this behavior is also observed in well hydrographs and shows the buffering effect that flow from the river has on drawdown in fully penetrating riparian wells in highly permeable unconfined aquifers relative contributions of river water to aquifer storage are calculated for et induced diurnal fluctuations of the water table at increasing distances from the river boundary failure to account for these spatial differences in drawdown related to the river source may explain some errors associated with estimating et from well hydrographs alone

characterization of active faulting beneath the strait of georgia british columbia southwestern british columbia and northwestern washington state are subject to megathrust earthquakes deep intraslab events and earthquakes in the continental crust of the three types of earthquakes the most poorly understood are the crustal events despite a high level of seismicity there is no obvious correlation between the historical crustal earthquakes and the mapped surface faults of the region on 24 june 1997 a m l 4 6 earthquake occurred 3 4 km beneath the strait of georgia 30 km to the west of vancouver british columbia this well recorded earthquake was preceded by 11 days by a felt foreshock m l 3 4 and was followed by numerous small aftershocks this earthquake sequence occurred in one of the few regions of persistent shallow seismic activity in southwestern british columbia thus providing an ideal opportunity to attempt to characterize an active near surface fault we have computed focal mechanisms and utilized a waveform cross correlation and joint hypocentral determination routine to obtain accurate relative hypocenters of the mainshock foreshock and 53 small aftershocks in an attempt to image the active fault and the extent of rupture associated with this earthquake sequence both p nodal and cmt focal mechanisms show thrust faulting for the mainshock and the foreshock the relocated hypocenters delineate a north dipping plane at 2 4 km depth dipping at 53 in good agreement with the focal mechanism nodal plane dipping to the north at 47 the rupture area is estimated to be a 1 3 km diameter circular area comparable to that estimated using a brune rupture model with the estimated seismic moment of 3 17 10 15 n m and the stress drop of 45 bars the temporal sequence indicates a downdip migration of the seismicity along the fault plane the results of this study provide the first unambiguous evidence for the orientation and sense of motion for active faulting in the georgia strait area of british columbia

hierarchical geostatistics and multifacies systems boise hydrogeophysical research site boise idaho 1 the geostatistical structure of a heterogeneous coarse fluvial aquifer is investigated with porosity data derived from neutron logs at a research well field boise hydrogeophysical research site or bhrs that was designed in part to support three dimensional geostatistical analysis of hydrologic and geophysical parameters recognizing that the coarse fluvial deposits include subdivisions units between bounding surfaces we adopt a hierarchical approach and examine the porosity geostatistics of the aquifer at three scales at the bhrs the saturated fluvial deposits as a whole maximum interwell spacing 80 m thickness 16 18 m are at hierarchical level 1 five subhorizontal units within these deposits four cobble dominated units and a channel sand can be traced across the central area of the bhrs and are at hierarchical level 2 and subunits patches or lenses in one of the level 2 units unit 4 are at hierarchical level 3 we use variography and porosity statistics to recognize nonstationarity at hierarchical level 1 and in one of the level 2 units unit 4 where the means and variances of porosity differences as a function of lag are not constant between distinct units and subunits respectively the geostatistical structure at level 1 is modeled with different horizontal and vertical structures that have different sills vertical sill greater than horizontal sill the difference in sills can be explained quantitatively by the summing of weighted sills from all individual units and combined units i e a given pair of different units where the weights are the proportions of data pairs contributing to the sills at each lag from the individual and combined units extension of this analysis leads to a weighted multistructure form of the variogram function whereby a global experimental variogram in a hierarchical system can be decomposed quantitatively into weighted component individual and combined unit or facies structures for any number of units or hierarchical levels such decomposition of the global horizontal variogram from the bhrs indicates that short range periodicity in that structure is due to both 1 combined unit structures associated with patches or lenses at hierarchical level 3 in unit 4 and 2 variations in thickness of unit 2 for hierarchical multifacies systems structure models fit to global horizontal and vertical experimental variograms may not be useful for subsequent stochastic modeling if the system on which the structure models are based is nonstationary

relocations of five yingjiang sequences china myanmar border details of seismogenic faults abstract five moderate sized earthquakes struck the yingjiang area china myanmar border where there is a lack of historical earthquakes and provided us an opportunity to study the seismogenic fault we relocate sequences via the hypodd method using the cross correlated arrival times the phase picking errors by the human analysts had only 0 01 s difference before and after 2009 however the p phase picking precision increased from the tenths to the hundredths place after 2009 and the relocation errors of hypodd simultaneously decreased by a factor of 2 the rupture dimensions are about 2 4 km for the five sequences the hypodd relocation errors are only 0 36 or 0 63 km for the two test clusters which are much smaller than the dimensions of the rupture areas the synthetic tests show no location bias from the distribution of the yunnan regional seismic network the relocations identify four linear features with the northwest north northwest or northeast direction for the 21 march 2008 3 september 2008 10 march 2011 and 30 may 2014 sequences orthogonal to the known major fault traces the relocations also suggest that the 10 march 2011 sequence is on a double layered fault dipping roughly 71 to the southwest focal mechanisms reveal a mixture of strike slip normal and reverse faulting

significance of porosity for stratigraphy and textural composition in subsurface coarse fluvial deposits boise hydrogeophysical research site recognition and quantitative characterization of subsurface stratigraphic units in coarse unconsolidated fluvial deposits are difficult because large grain size and the large scale of sedimentary structures make direct interpretation from core difficult or impossible in this paper we use porosity data from well logs and grain size distribution gsd data from core to investigate four pebble and cobble dominated units that have been identified in porosity logs in deposits at a research well field boise hydrogeophysical research site lacking direct observation at an appropriate scale questions about distribution of parameters and textural composition in these units are analyzed with statistical tests the four pebble and cobble dominated porosity stratigraphic units may be grouped into two types 1 units 1 and 3 have low porosity mean 0 17 0 18 and low porosity variance and 2 units 2 and 4 have higher porosity mean 0 23 0 24 and higher porosity variance based on gsd data core samples are subdivided into five lithotypes the five lithotypes occur in different proportions and have different vertical transition probability characteristics in the two types of units 1 units 1 and 3 have only framework gravel dominated lithotypes and have random vertical transition probability between these two lithotypes and 2 units 2 and 4 consist of both framework gravel dominated and sand or matrix dominated lithotypes and have structured vertical transition probability the two framework gravel dominated lithotypes occur in all four stratigraphic units but have distinctly lower porosity in units 1 and 3 i e tighter packing than in units 2 and 4 looser packing considering the repeated stratigraphic occurrence of and the statistical significance of differences between the two types of units both the individual unit distinctions and the two unit groupings appear to be valid it is reasonable to interpret that the observed packing differences associated with units 1 and 3 compared with units 2 and 4 are related to different sedimentary processes that produce different bedforms or grain fabrics perhaps under different bedload transport rates

analytical modeling of saturated zone head response to evapotranspiration and river stage fluctuations summary we investigate the response of the saturated zone unconfined aquifer to evapotranspiration et flux at ground surface we neglect fluid flow and storage in the unsaturated zone and treat et as a sinusoidal forcing function at the watertable the linearized kinematic condition is imposed at the watertable analytical solutions are developed for the case of flow in a domain of a semi infinite extent to simulate response in a domain bounded by a river and b infinite lateral extent to simulate the response in a domain with no river boundaries these solutions are fitted to observed groundwater head fluctuations recorded in observation wells at the boise hydrogeophysical research site in idaho and the larned research site in kansas estimates of the amplitude of the et flux aquifer hydraulic conductivity specific storage and specific yield are obtained and these compare well to published results from pumping tests conducted at the site the field exercise is used to explore the potential for using groundwater head fluctuations to estimate et and hydraulic parameters of unconfined aquifers

alpine structures and metamorphism at the pillonet klippe a remnant of the austroalpine nappe system in the italian western alps a detailed petrofabric analysis leads to the following consequences at the pillonet klippe a remnant of the austroalpine dent blanche sesia lanzo nappe system in the western alps two nappe forming events have to be distinguished the first one marks the beginning the second one the end of alpine tectonometamorphic evolution while the first event is correlated to the early alpine high pressure low temperature subduction zone metamorphism the second event has no counterpart within the alpine metamorphic history post lepontine cold thrusts act at c 250 c cutting through early alpine nappe boundaries and pile up a new sequence of nappes with different internal lithologies structures and relics of late and early alpine metamorphism

fabric development in a fragment of tethyan oceanic lithosphere from the piemonte ophiolite nappe of the western alps valtournanche italy abstract south of the matterhorn the valtournanche cuts through alpine serpentinites metagabbros meta pillowbasalts and metasediments dismembered remnants of the jurassic tethyan oceanic crust reassembled in the piemonte ophiolite nappe this study deals with a serpentinized ultramafic to mafic layered complex stemming from a spreading ridge environment cumulus fabrics of various kinds can be read through antigorite pseudomorphs still allowing the detailed reconstruction of deep oceanic crust relics of igneous and metamorphic olivine prove crustal conditions during deformation fracturing of cumulus olivine was succeeded by plastic flow that activated low temperature slip systems concomitant recrystallization produced metaperidotite only along shear zones which are ascribed to subduction of the oceanic crust at the turning point from subduction to obduction a static metamorphic event resulted in recovery and grain growth of recrystallized olivine afterwards serpentinization of the complex took place still under static conditions deformation of the serpentinite led to a sequence of four phases involving non penetrative cleavage formation stretching and folding this deformation is structurally related to obduction of the complex although partly accompanied by subduction zone metamorphism final movements of the ophiolites were due to cataclastic thrusting forming subnappe boundaries

stress in western canada from regional moment tensor analysis more than 180 regional moment tensor rmt solutions for moderate sized earthquakes m 4 are used to examine the contemporary stress regime of western canada and provide valuable information relating to earthquake hazard analysis the overall regional stress pattern shows mainly ne sw oriented p axes for most of western canada with local variations in the northern cordillera the maximum compressive stress direction 1 varies from east west to north south to ne sw from south to north the stress direction 1 is consistent with the p axis direction for the largest earthquakes except in the central and northern mackenzie mountains where there is a 16 difference the yakutat collision zone shows a steady change in 1 from east west in the east to north south in the west in the canada united states border region rmt solutions suggest a north south compressional regime may extend through southern british columbia and northern washington to the eastern cordillera in the vancouver island puget sou