surface pressure and mountain drag for transient airflow over a mountain ridge abstract the linear problem of rotating stratified adiabatic hydrostatic boussinesq airflow over a mountain ridge is solved analytically for the case where the spatially uniform normally incident airflow is the sum of a steady and sinusoidally varying component the mountain generates a response at the fundamental frequency of the wind and all higher harmonics during flow acceleration the evanescent vertically decaying modes deepen and broaden the high low pressure asymmetry across the ridge and increase the mountain drag in contrast the evanescent modes for steady airflow product only a symmetric mountain anticyclone that generates no drag the influence of the acceleration is more pronounced for mesoscale and synoptic scale ridges i e ridges whose rossby number is order unity or smaller and when the fundamental period is near the inertial period the transience also amplifies the magnitude of the maximum wave drag over its value predicted from steady airflow theory using the instantaneous

numerical simulation of katabatic flow with changing slope angle a large eddy simulation les model and the advanced regional prediction system arps model which does not resolve turbulent eddies are used to study the effect of a slope angle decrease on the structure of katabatic slope flows for a simple uniform angle slope simulations from both models produce turbulence kinetic energy and momentum budgets that are in good overall agreement simulations of a compound angle slope are compared to a uniform angle slope to demonstrate how a changing slope angle can strongly affect the strength of katabatic flows both arps and the les model show that slopes with a steep upper slope followed by a shallower lower slope concave shape generate a rapid acceleration on the upper slope followed by a transition to a slower evolving structure characterized by an elevated jet over the lower slope in contrast the case with uniform slope having the same total height change yields a more uniform flow profile with stronger winds at the slope bottom higher average slope in the uniform slope angle case generates greater gravitational potential energy which is converted to kinetic energy at the bottom of the slope analysis of the total energy budget of slope flows indicates a consistent structure where potential energy generated at the top of the slope is transported downslope and converted into kinetic energy near the slope base

the yerba buena mud record of the last interglacial predecessor of san francisco bay california the yerba buena mud member of the san antonio formation is an upper pleistocene estuarine deposit that records a marine transgression during the last interglacial into the valley today filled by san francisco bay these sediments now lie between 25 70 m below mean sea level and are not exposed subaerially foraminifers sand sized diatoms seeds fish elements molluscan shells and other microfossils preserved in core samples trace environmental changes that occurred as sea level rose this multitaxon approach permits biostratigraphic analysis of subsurface units even when core samples have undergone extended storage and consequent deterioration of calcareous microfossils foraminifers are preserved in only 22 of the yerba buena mud samples but more than 70 of the samples contain diatoms or other taxa useful for paleoenvironmental analyses in the yerba buena mud 32 species of foraminifers are present these species are predominantly estuarine and nearshore marine fauna seven species make up more than 98 of the population in all samples ammonia beccarii buccella frigida buliminella elegantissima elphidiella hannai elphidium excavatum elphidium gunteri and elphidium magellanicum foraminifers and sand sized diatoms define five biofacies that indicate changing environmental conditions during a single transgression into the yerba buena bay biofacies present in the lower portion of the unit indicate environments ranging from brackish such as those prevailing in the upper reaches of the present estuary to the higher salinity of the present central bay biofacies in the upper part of the unit indicate coastal marine salinity and lower water temperature conditions unlike those in the present estuary but prevalent along the outer central california coast today the transgressional record in the yerba buena mud is a useful example of environmental changes that might result from the effect of sea level rise in major holocene estuaries

the hydraulics of a stratified fluid flowing through a contraction the steady hydraulics of a continuously stratified fluid flowing from a stagnant reservoir through a horizontal contraction was studied experimentally and theoretically as the channel narrows the flow accelerates through a succession of virtual controls at each of which the flow passes from subcritical to supercritical with respect to a particular wave mode when the narrowest section acts as a control the flow is asymmetric about the narrowest section supercritical in the divergent section and selfsimilar throughout the channel with increased flow rate a new enclosed self similar solution was found with level isopycnals and velocity uniform with depth

the interaction of katabatic flow and mountain waves part ii case study analysis and conceptual model via numerical analysis of detailed simulations of an early september 1993 case night the authors develop a conceptual model of the interaction of katabatic flow in the nocturnal boundary layer with mountain waves mki a companion paper part i describes the synoptic and mesoscale observations of the case night from the atmospheric studies in complex terrain ascot experiment and idealized numerical simulations that manifest components of the conceptual model of mki presented herein the reader is also referred to part i for detailed scientific background and motivation the interaction of these phenomena is complicated and nonlinear since the amplitude wavelength and vertical structure of the mountain wave system developed by flow over the barrier owes some portion of its morphology to the evolving atmospheric stability in which the drainage flows develop simultaneously katabatic flows are impacted by the topographically induced gravity wave evolution which may include significantly changing wavelength amplitude flow magnitude and wave breaking behavior in addition to effects caused by turbulence including scouring perturbations to the leeside gravity wave structure at altitudes physically distant from the surface based katabatic flow layer can be reflected in the katabatic flow by transmission through the atmospheric column the simulations show that the evolution of atmospheric structure aloft can create local variability in the surface pressure gradient force governing katabatic flow variability is found to occur on two scales on the meso due to evolution of the mountain wave system on the order of one hour and on the microscale due to rapid wave evolution short wavelength and wave breaking induced fluctuations it is proposed that the mki mechanism explains a portion of the variability in observational records of katabatic flow

another look at downslope windstorms part i the development of analogs to supercritical flow in an infinitely deep continuously stratified fluid abstract numerical simulations are conducted to examine the role played by different amplification mechanisms in the development of large amplitude mountain waves it is shown that when the static stability has a two layer structure the nonlinear response can differ significantly from the solution to the equivalent linear problem when the parameter nh u is as small as 0 3 in the cases where the nonlinear waves are much larger than their linear counterparts the highest stability is found in the lower layer and the flow resembles a hydraulic jump simulations of the 11 january 1972 boulder windstorm are presented which suggest that the transition to supercritical flow forced by the presence of a low level inversion plays an essential role in triggering the windstorm the similarities between breaking waves and nonbreaking waves which undergo a transition to supercritical flow are discussed

flow through discovery gap abstract a narrow gap discovery gap in the east azores fracture zone at 37 n in the eastern atlantic provides a channel for the exchange of bottom water between the madeira and iberian abyssal basins a detailed survey defines its length 150 km width 10 50 km depth of sills near 4800 m and sediment thickness 0 500 m year long measurements of deep flow are made from six moorings and ten current meters mean flows are about 5 cm s 1 these data are supplemented by 10 days of float tracking near 4700 m and numerous density profiles within and around the gap a persistent southwest northeast flow of dense water is found in discovery gap and the flux of water colder than a potential temperature of 2 05 c is measured to be 0 21 04 106 m3 s 1 this discharge spreads over an area of about 1011 m2 beyond the gap exit where it is warmed both by geothermal heating and by mixing with overlying water an estimate of 1 5 to 4 cm2 s 1 is derived for the diapycnal diffusivity similar to values dete

interaction of katabatic winds and near surface temperatures in the antarctic 1 a two dimensional mesoscale model was applied to simulate wintertime katabatic winds in the antarctic coastal region simulations were made for a constant slope angle with the slope height varying and for fixed slope heights with the slope angle varying thermal wind opposed the katabatic flow near the foot of the slope but enhanced it over the high plateau the steeper and higher the slope the stronger the effect on the plateau the 2 m potential temperature decreased down the slope toward sea ice because 1 the katabatic wind resulted in the accumulation of cold near surface air over the sea ice and the lower parts of the slope 2 over the flat sea ice zone the stratification was stronger and 3 the shallow slope was within the strong surface inversion from over the sea ice with a slope aspect ratio of 5 m km 1 and a slope height below 1000 m 2 m temperature t2m decreased down the slope but for slope heights of 1500 m and more t2m increased down the slope adiabatic warming and because of the stronger wind enhanced turbulent mixing of the warmer air from aloft contributed to the warming for slope angles ranging from 1 to 20 m km 1 with a small slope height of 500 m t2m decreased down the slope but not monotonically whereas with a slope height of 2000 m yielding stronger winds and larger adiabatic warming t2m increased monotonically down the slope the model results were supported by observations from several antarctic sites with different topographic conditions

regional weather prediction with a model combining terrain following and isentropic coordinates part i model description abstract a short range numerical prediction model which is part of a real time 3 h data assimilation and forecast system is described the distinguishing feature of the model is the use of terrain following coordinate surfaces in the lower troposphere combined with isentropic surfaces aloft such a hybrid coordinate system allows modeling of processes in a convectively unstable boundary layer while retaining tile advantages of coordinates in representing upper tropospheric frontal and jet stream structures the hybrid approach used in this model represents a in major departure from previous hybrid formulations in atmospheric models oven though it has been used for more than ten years in oceanic modeling part i of this two part paper contains a thorough description of the model and the results of validation experiments results of north american case studies wig be reported in part ii

transient cold air drainage down a shallow valley abstractdrainage of cold air down a small valley and associated near surface wind maxima are examined from 20 stations with sonic anemometers at 1 m and from a 20 m tower that includes six sonic anemometers in the lowest 5 m deployed in the shallow cold pool experiment scp the small valley is about 270 m wide and 12 m deep with a downvalley slope of 2 3 the momentum budget indicates that the flow is driven by the buoyancy deficit of the flow and opposed primarily by the stress divergence while the remaining terms are estimated to be at least an order of magnitude smaller this analysis also reveals major difficulties in quantifying such a budget due to uncertainties in the measurements sensitivity to choice of averaging time and sensitivity to measurement heights wind maxima occur as low as 0 5 m in the downvalley drainage flow the lowest observational level the downvalley cold air drainage and wind maxima are frequently disrupted by transient modes that sometimes lead to significant vertical mi

the interaction of katabatic flow and mountain waves part i observations and idealized simulations abstract the mutual interaction of katabatic flow in the nocturnal boundary layer nbl and topographically forced gravity waves is investigated due to the nonlinear nature of these phenomena analysis focuses on information obtained from the 1993 atmospheric studies in complex terrain field program held at the mountain canyon plains interface near eldorado canyon colorado and idealized simulations perturbations to katabatic flow by mountain waves relative to their more steady form in quiescent conditions are found to be caused by dynamic pressure effects based on a local froude number climatology case study analysis and the simulations the dynamic pressure effect is theorized to occur as gravity wave pressure perturbations are transmitted through the atmospheric column to the surface and through altered horizontal pressure gradient forcing to the surface based katabatic flows it is proposed that these perturbations are a routine feature in the atmospheric record and represent a significant p

analysis of gravity waves generated at the top of a drainage flow abstract drainage or katabatic flows are common mesoscale circulations established as a result of differential radiative cooling of near surface air masses in sloping terrain the initial irruption of these flows with sudden shifts in wind speed and direction may result in vertical displacements of air parcels from their equilibrium position which prove to be a common source of internal gravity waves this paper illustrates this mechanism and describes the main features of the oscillations following the study of observational data gathered throughout one night during the stable atmospheric boundary layer experiment in spain 2006 sables2006 field campaign pressure differences measured by microbarometers set at different levels of a tower help to interpret the evolution of other atmospheric variables provide a detailed picture of the irruption of a drainage current and reveal the formation of gravity waves at its top the main parameters of the waves are derived from wavelet cross correlation of p

carbon isotope diatom and pollen evidence for late holocene salinity change in a brackish marsh in the san francisco estuary analysis of diatoms pollen and the carbon isotopic composition of a sediment core from a brackish marsh in the northern part of the san francisco estuary has provided a paleosalinity record that covers the past 3000 yr changes in marsh composition and diatom frequencies are assumed to represent variations in freshwater inflow to the estuary three periods of relatively high salinity low freshwater inflow are indicated 3000 to 2500 cal yr b p 1700 to 730 cal yr b p and ca a d 1930 to the present the most recent period of high salinity is primarily due to upstream storage and water diversion within the sacramento san joaquin watershed although drought may also have been a factor the two earlier high salinity periods are likely the result of reduced precipitation low salinity high freshwater flow is indicated for the period 750 cal yr b p to a d 1930 c 2001 university of washington

what have natural and human changes wrought on the foraminifera of san francisco bay late quaternary estuaries abstract in this study we compare the foraminifera of modern south san francisco bay with fossils from sediments of a previous estuary at 125 ka to provide a basis for interpreting the impact of natural and human change on the benthic ecosystem all the species found in the pleistocene sediments of this study are estuarine and or shallow water species occurring commonly in san francisco bay today except for the introduced foraminifer trochammina hadai a native of japan that was not found in samples taken in san francisco bay before 1983 the biodiversity and species composition of the fossil and modern assemblages before the introduction of t hadai are nearly identical suggesting that the environmental and physical changes in the 125 000 year old and modern estuaries have not had a significant effect on the meiofauna of the bay in contrast modern anthropogenic change in the form of species introductions has impacted the modern foraminiferal assemblage t hadai began to dominate the modern assemblage a decade after its introduction similar to the recorded impacts of introductions of marine metazoan invertebrate species the dominance of t hadai changed species proportions in the post 1980s foraminiferal assemblage however no known extinctions in the native foraminiferal fauna occurred

strong downslope wind events in ammassalik southeast greenland abstractammassalik in southeast greenland is known for strong wind events that can reach hurricane intensity and cause severe destruction in the local town yet these winds and their impact on the nearby fjord and shelf region have not been studied in detail here data from two meteorological stations and the european centre for medium range weather forecasts interim re analysis era interim are used to identify and characterize these strong downslope wind events which are especially pronounced at a major east greenland fjord sermilik fjord within ammassalik their local and regional characteristics their dynamics and their impacts on the regional sea ice cover and air sea fluxes are described based on a composite of the events it is concluded that wind events last for approximately a day and seven to eight events occur each winter downslope wind events are associated with a deep synoptic scale cyclone between iceland and greenland during the events cold dry air is advected down the ice sheet

the role of wave dynamics and small scale topography for downslope wind events in southeast greenland abstractin ammassalik in southeast greenland downslope winds can reach hurricane intensity and represent a hazard for the local population and environment they advect cold air down the ice sheet and over the irminger sea where they drive large ocean atmosphere heat fluxes over an important ocean convection region earlier studies have found them to be associated with a strong katabatic acceleration over the steep coastal slopes flow convergence inside the valley of ammassalik and in one instance mountain wave breaking yet for the general occurrence of strong downslope wind events the importance of mesoscale processes is largely unknown here two wind events one weak and one strong are simulated with the atmospheric weather research and forecasting wrf model with different model and topography resolutions ranging from 1 67 to 60 km for both events but especially for the strong one it is found that lower resolutions underestimate the wind speed because they misrepresent the steepness of the

gap winds and wakes sar observations and numerical simulations the nature of terrain induced gap winds and wakes in the atmosphere is examined using surface wind data from synthetic aperture radar sar and the shallow water equations the shallow water model is used to predict the types of wake jet wind patterns that might occur behind an idealized pair of bell shaped hills with a gap between them a regime diagram is constructed based on the width of the gap and the upstream froude number specific predictions of the model are found to compare moderately well with sar data from four examples of airflow near unimak island in the aleutian chain the model predicts the observed wakes and jets including jets that exceed the upstream speed theoretical analysis considers the relative importance of rising terrain and narrowing valley walls in the acceleration of gap winds wind speeds in the wake region are controlled by the bernoulli function and regional pressure gap winds therefore are streams of air that have avoided bernoulli loss over the terrain by passing through gaps the speed of gap winds can exceed the upstream speed only in ridgelike situations when the regional leeside pressure is lower than the upstream pressure

stratified flow over a mountain with a gap linear theory and numerical simulations linear theory and numerical simulations are used to investigate gap flows both gaps embedded in a long mountain ridge and gaps located between two isolated mountain peaks are considered the study mainly focuses on level gaps so as to isolate three dimensional effects from two dimensional gravity wave propagation special attention is given to qualitative differences between the linear and the nonlinear flow regimes the linear regime being defined by the absence of gravity wave breaking in the linear regime wind and pressure perturbations along a level gap axis are found to be qualitatively similar to those over a mountain ridge or peak but of lower amplitude and longer horizontal wavelength they are caused by vertically propagating gravity waves radiating from the mountain ridges peaks towards the gap axis and by low level confluence within the gap in the nonlinear regime however these two processes are of minor importance due to upstream blocking and low level wave breaking instead the pressure difference across the mountain ridge primarily drives the gap flow which tends to be decoupled from the flow over the adjacent ridge in contrast to the linear regime gap winds are as strong as or even stronger than the winds over the mountain ridge surface friction is found to reduce the near surface wind speed more strongly for mountain ridges than for gaps copyright 2002 royal meteorological society

strontium isotope ages of the marine merced formation near san francisco california abstract the strontium isotopic compositions of foraminifers elphidiella hannaiwere determined to refine the age of coastal sediments of the merced formation and to evaluate the relation between transgressive regressive cycles and pleistocene glacio eustatic sea level fluctuations relatively good age resolution 0 1 myr is possible in the upper part of the section the sr isotope ages provide strong supporting evidence for the fission track ages of an ash layer at the top of the formation 0 45 myr as well as recent age estimates for the mammoth fossil of 0 45 myr sr isotope ages in the upper part of the section also confirm that marine nonmarine cyclic sedimentation in the merced formation is controlled by glacial interglacial cycles good age resolution for the lower part of the section is not possible due to little variation of the87sr 86sr ratio in global sea water between 2 4 and 4 3 myr the age of the base of the formation is constrained only between 2 4 and 4 8 myr sediment accumulation rates in the upper portion of the merced formation between 0 and 720 m are significantly higher than those calculated for the basal portion between 720 and 1670 m the change in accumulation rate may be due to increased continental weathering rates and or increased tectonic subsidence beginning about 0 8 myr ago

temporal changes in foraminiferal faunas and impact of pollution in sandebukta oslo fjord abstract sandebukta oslo fjord norway is an inlet with depths up to 70 m characterised by estuarine water stratification an influx of pollutants and a mudflat in the inner part the distribution of its foraminiferal fauna displays essentially an estuarine pattern but also reveals significant subrecent changes as demonstrated by means of 9 sediment cores supplemented by a larger number of sea bed surface samples the faunal changes have taken place during the last 100 years and are summarized as follows 1 upwards increase in size of the total population shown by the sediment cores 2 reduction in the relative frequency of calcareous foraminifera upwards in the cores so that the recent fauna of the inlet consists mainly of arenaceous species 3 alterations in the species composition of populations most pronounced in deeper waters faunal comparisons with outer parts of the fjord system suggest that these changes are at least partially induced by pollution originating from human activity in addition post mortem destruction of foraminiferal tests is considered as a possibly important modifying factor requiring further study an important additional reason for the faunal turnover found in the mudflat seems to be successive shallowing during progradation

differences in radiocarbon age between shell and charcoal from a holocene shellmound in northern california abstract the west berkeley shellmound the oldest well dated archaeological site in the san francisco bay region contains shell and charcoal ranging in age from ca 1200 to 5700 cal yr b p radiocarbon ages of marine shell and charcoal collected from fifteen stratigraphic levels in the west berkeley shellmound suggest changes in the 14 c content of san francisco bay surface waters relative to the atmosphere the oceanic reservoir age over the past 5000 yr the reservoir age of san francisco bay waters fluctuated between 870 and 170 14 c yr over the past 5000 yr with the lowest values occurring 2900 to 3800 cal yr b p and the highest values between 1200 and 2000 cal yr b p changes in the radiocarbon reservoir age may be due to changes in the strength of seasonal wind driven upwelling off coastal california where upwelling brings 14 c depleted waters to the surface the period of lowest r values at 3500 to 3900 cal yr b p is coincident with relatively low salinity in san francisco bay indicating high freshwater inflow and wet climate in california based on lake level records the period of high r values 1200 2000 cal yr b p is coincident with one of the driest periods in california during the late holocene these data suggest a link between coastal upwelling and precipitation over central california the age of the top of west berkeley mound and several other mounds in the san francisco bay region 1100 to 1300 cal yr b p coincides with a prolonged dry period in california and low river inflow to san francisco bay perhaps the sites were abandoned because of the drought

increasing reserves in a mature giant wilmington field los angeles basin part 1 reservoir characterization to identify bypassed oil with estimated reserves of over 2 8 billion bbl oil the supergiant wilmington field is the largest productive area in the los angeles basin one of the world s most prolific petroleum provinces similar to most other fields in the basin wilmington produces from thick sequences of upper miocene pliocene slope and basin floor turbidites ranging from well indurated to unconsolidated in character due to a range of factors enhanced recovery in these reservoirs has been incomplete or inefficient with the result that a substantial remaining resource exists to help devise improved methods for exploiting this resource the u s department of energy has included portions of wilmington field in its class 3 slope and basin clastic reservoirs oil recovery field demonstration program at present two projects are underway one aimed at identifying bypassed pay and the other project aimed at improving tertiary recovery operations both projects have employed advanced reservoir characterization techniques and have demonstrated considerable success results of this work should have wide application to slope and basin clastic reservoirs elsewhere part 1 of the following two part paper presents a summary of work completed thus far

thermally forced low froude number flow past three dimensional obstacles abstract the present study extends the discussion of the flow of a density stratified fluid past three dimensional obstacles for froude number o 1 to flows past an isolated obstacle with heated cooled surface the study focuses on a response of thermally forced stratified flows representative of mesoscale flows past mountainous islands such as hawaii or taiwan in order to minimize the span of the parameter space uniform ambient wind and stratification axially symmetric bell shaped hills with moderate slopes representative of mesoscale mountains and a simple thermal forcing function that mimics natural effects over mountainous islands are assumed the earth s rotation surface friction viscosity dissipation and moisture are neglected with these simplifications flows can be characterized with two parameters the froude number and a characteristic scale of thermal forcing defined later in this paper the principal question addressed in this study is under what circumstances will a transition occur

gap winds in a fjord part ii hydraulic analog abstract a simple shallow water model of gap wind in a channel that is based upon hydraulic theory is presented and compared with observations and output from a 3d mesoscale numerical model the model is found to be successful in simulating gap winds the speed and depth of gap wind flow is strongly controlled by topography horizontal or vertical channel contractions can act to force strong shallow supercritical flow downwind and light deep subcritical flow upwind force balance analysis of the hydraulic model output confirms mesoscale model results and indicates that the prime force balance in gap wind is between external pressure gradient and friction for supercritical flow and between external pressure gradient and height pressure gradient for subcritical flow this force balance changes near channel controls when the balance is between advection and height pressure gradient sensitivity analyses show positive sensitivity of gap wind speed to changes in discharge and external pressure gradient nega

a cross section of the los angeles area seismically active fold and thrust belt the 1987 whittier narrows earthquake and earthquake hazard retrodeformable cross sections across the los angeles area interpret the pliocene to quaternary deformation to be a developing basement involved fold and thrust belt the fold and thrust belt is seismically active as evidenced by the 1987 whittier narrows earthquake ml 5 9 and the 1971 san fernando earthquake mw 6 6 the structural geology of the los angeles area is dominated by three major compressional uplift trends 1 the palos verdes anticlinorium and western shelf 2 the santa monica mountains anticlinorium and 3 the verdugo mountains san rafael hills and the san gabriel mountains these trends result from major thrust ramps off a detachment s at 10 15 km depth thrusts of the verdugo mountains san rafael hills and the san gabriel mountains reach the surface the other two uplifts are associated with blind thrusts compressional seismicity is concentrated along these thrust ramps the 1987 whittier narrows earthquake probably occurred on the elysian park thrust which underlies the santa monica mountains anticlinorium the thrust interpretation accounts for the geometry of the anticlinorium the seismological characteristics of the earthquake and the geometry of coseismic uplift the earthquake and aftershocks occurred within a structurally complex narrow zone of miocene and pliocene northwest trending faults that cross the anticlinorium at a high angle these northwest trending faults are interpreted to be reactivated faults now behaving as tears in the elysian park thrust and not the result of active right lateral deformation extending into the whittier narrows area our analysis suggests the whittier narrows earthquake sequence occurred within a structurally weakened zone along the elysian park thrust we also suggest that the whittier fault is not an important quaternary structure and may not be seismogenic the regional cross section is a nonunique solution and other possible solutions are considered multiple solutions arise from the presence of two intersecting compressional belts in the los angeles area the transverse ranges and the northern peninsular ranges the belts may be due to one or more regional detachments and the northern peninsular ranges may be northeast or southwest vergent the deformed top of the crystalline basement along the regional cross section requires a minimum of 15 0 km of north south convergence between the palos verdes hills and the san andreas fault regardless of the structural solution restoration of our cross section solution requires 21 4 km of north south convergence on top of the crystalline basement including 6 4 km of slip continuing offshore to make structures of the continental borderland and 29 7 km of convergence on the basal detachment geologic relationships suggest major shortening started between early and late pliocene time 2 2 4 0 ma which yields a minimum convergence rate of 3 8 6 8 mm yr between the palos verdes hills and the san andreas fault convergence rates for our solution range from 5 4 to 13 5 mm yr between the edge of the continental borderland and the san andreas fault slip rate estimates for the elysian park thrust along the eastern portion of the santa monica mountains anticlinorium are 2 5 5 2 mm yr if the 1987 whittier narrows earthquake is the characteristic earthquake along the 170 km long anticlinorium then recurrence intervals are estimated to be 5 6 12 1 years this recurrence is higher than the historic seismic record along the santa monica mountains anticlinorium and suggests that 1 our slip rates are too high 2 some crustal shortening is taken up aseismically and or 3 earthquakes larger than the 1987 whittier narrows earthquake will occur along the anticlinorium but less frequently

paleochannel sands as conduits for hydrocarbon leakage across faults an example from the wilmington oil field california this article evaluates the impact of a submarine channel sand in the western wilmington oil field california on hydrocarbon accumulation and leakage across boundary faults the wilmington field is in a broad anticline broken into 10 fault blocks by normal faults the coarse grained channel deposit named t4 is identified in fault blocks i through iii within the tar zone a lower pliocene turbidite deposit and the shallowest productive zone in the area the channel deposit incised into three sand units t2 t5 and t7 evidences of tilted oil water contacts owc owc cutting structure depth contours scattered oil traces and fault seal analysis all indicate that the channel deposit is responsible for hydrocarbon leakage across the boundary faults the leakage occurs in the three channel incised sand units t2 t5 and t7 in fault block i hydrocarbons in the three sands charge the channel sand at the structural culmination and then leak across the eastern boundary wilmington fault into the wet s sand directly above the tar zone on the hanging wall block in fault block iia hydrocarbons from the t5 and t7 sands pool in the channel sand on the north flank and leak across the eastern boundary ford fault into the s sand on the hanging wall block this leakage across faults caused depletion of almost all hydrocarbon accumulations in the three channel incised sands in fault block i the leakage also raised owcs on the north flank in fault block iia resulting in tilted owcs in the two channel incised sand intervals

age dating and the orbital theory of the ice ages development of a high resolution 0 to 300 000 year chronostratigraphy using the concept of orbital tuning a continuous high resolution deep sea chronostratigraphy has been developed spanning the last 300 000 yr the chronology is developed using a stacked oxygen isotope stratigraphy and four different orbital tuning approaches each of which is based upon a different assumption concerning the response of the orbital signal recorded in the data each approach yields a separate chronology the error measured by the standard deviation about the average of these four results which represents the best chronology has an average magnitude of only 2500 yr this small value indicates that the chronology produced is insensitive to the specific orbital tuning technique used excellent convergence between chronologies developed using each of five different paleoclimatological indicators from a single core is also obtained the resultant chronology is also insensitive to the specific indicator used the error associated with each tuning approach is estimated independently and propagated through to the average result the resulting error estimate is independent of that associated with the degree of convergence and has an average magnitude of 3500 yr in excellent agreement with the 2500 yr estimate transfer of the final chronology to the stacked record leads to an estimated error of 1500 yr thus the final chronology has an average error of 5000 yr