kaikoura canyon new zealand active conduit from near shore sediment zones to trench axis channel kaikoura canyon is one of a few major active conduits between a near shore sediment transport system and a deep ocean channel it is the sink for mobile zones of gravel sand and mud that migrate northwards off northeastern south island new zealand it is presently the primary source for the 1500 km long hikurangi channel which supplies overbank turbidites to a filled trench an ocean plateau basin and a distal fan drift swath data seismic profiles side scan sonographs aerial photographs cores grab samples and current meter data are used to define the shape and texture of the canyon and adjacent shelf in order to better understand how coastal processes and canyon interact to supply sediment to the deep ocean kaikoura canyon is 60 km long up to 1200 m deep and generally u shaped in profile its head is within 500 m of the shore and within 200 m of rocky projections from the shore platform in a mountain backed bay without large rivers the canyon head incises the 18 m depth contour and boulders pebble gravel and megarippled coarse sand reach the canyon rim fine sand migrating northward along the shelf under the influence of waves and currents is trapped in a southward projecting canyon head gully which incises the thickest part of the holocene sediment prism it is estimated that about 1 5 106 m3 of sediment falls into the canyon head each year tensional fractures around the canyon rim suggest that sediments in the canyon head gully are unstable gravel turbidites with post last glacial age shells are at or near the seabed in the lower canyon but are blanketed by many thin silt and sand possibly storm generated turbidites in the upper canyon the top gravel contains a twig that is about 170 years old suggesting that the last major collapse in the canyon head coincides with many onshore rockfalls triggered by rupture of a major strike slip plate boundary fault in about 1833 an underlying gravel is about 300 years old and may again coincide with fault rupture most of the large earthquake triggered failures may ignite to form self perpetuating autosuspension flows that feed a 1500 km long deep sea turbidite channel

the palsar polarimetric mode for sea oil slick observation a study on sea oil slick observation by means of l band polarimetric synthetic aperture radar sar data is accomplished it is based on different sea surface scattering mechanism expected with and without surface slicks polarimetric measurements are processed by means of a simple and very effective filtering technique which is electromagnetically based on the mueller scattering matrix moreover some polarimetric features evaluated on both slick free and slick covered sea surfaces are analyzed for confirming the filter output experiments are accomplished on the polarimetric sar data acquired by the phased array type l band synthetic aperture radar palsar sensor mounted on board of the advanced land observing satellite alos and are relevant to oil slick due to a tank accident and look alikes results demonstrate for the first time that l band polarimetric sar measurements are useful for oil slick observation purposes and witness the capability of the alos palsar data for such application

sequence stratigraphy depositional history and middle to late quaternary sea levels of the ventura shelf california abstract high resolution shallow seismic profiles from the ventura shelf reveal two contrasting structurally controlled styles of deposition on the northern shelf folded plio pleistocene strata comprising the south limb of the ventura avenue anticline are unconformably overlain by undeformed late quaternary strata in contrast a thicker section of undeformed prograding deltaic sequences preserved on the subsiding southern shelf contains a detailed record of at least five middle and late quaternary glacioeustatic sea level oscillations a transgressive surface at 140 m in upper pleistocene saugus deposits is overlain by transgressive and highstand systems tracts a shelf margin systems tract subsequently developed as the sea level lowered marking the end of saugus deposition thereafter over 50 m of post saugus upper pleistocene sediment accumulated during a period of smaller scale sea level oscillations followed by the development of a pair of marine terraces presently at 50 and 33 m and a large fluvial channel now buried at 113 m correlations of saugus and terrace marker horizons with the middle to late quaternary paleosea level curve suggest development of the saugus marker horizons during oxygen isotopic stages 7 5e and formation of the terraces during wisconsinan high sea levels maximum rates of vertical separation on the oak ridge and pitas point faults are estimated to be 0 13 and 0 30 m 1000 yr respectively

oil spill detection in radarsat and envisat sar images we present algorithms for automatic detection of oil spills in synthetic aperture radar sar images the algorithms consist of three main parts namely 1 detection of dark spots 2 feature extraction from the dark spot candidates and 3 classification of dark spots as oil spills or look alikes the algorithms have been trained on a large number of radarsat and envisat advanced synthetic aperture radar asar images the performance of the algorithm is compared to manual and semiautomatic approaches in a benchmark study using 59 radarsat and envisat images the algorithms can be considered to be a good alternative to manual inspection when large ocean areas are to be inspected

mapping sea surface oil slicks using radarsat 2 quad polarization sar image 1 polarimetric sar decomposition parameters average alpha angle and entropy h are estimated for oil slick contaminated sea surfaces and slick free conditions using a radarsat 2 quad polarization sar image the values of h and within oil slick areas are significantly higher than those of the ambient sea surface indicating the dominance of bragg scattering for the slick free ocean and non bragg scattering for the oil slick area in land classification the conformity coefficient is often used to discriminate surface scattering with double bounce or volume scattering based on this rationale we also develop a method using as a logical scalar descriptor to map oil slicks under low to moderate wind conditions the proposed method is assessed using a radarsat 2 quad polarization sar image of oil slicks in the gulf of mexico analysis shows that when is positive the sea surface is slick free whereas is negative for oil slick areas this method provides a simple and effective mapping technique for oil slick detection

sar imaging of ocean surface oil seep trajectories induced by near inertial oscillation abstract in the gulf of mexico repeated satellite synthetic aperture radar sar observations show circular trajectories of oil slicks with a radius of several km some circles overlay onto each other while in other cases the circles are modified by the ambient current to form a train of spirals we show that these sar observed features originate from oil seeps of the ocean bottom and the circles are induced by near inertial oscillation nio from the sar images we have estimated the ambient current velocity from a train of spiral like circles and verified the nio by calculating its oscillation period in this study we also analyze time series of wind and velocity profiles obtained from a moored buoy and acoustic doppler current profilers mounted on oil platforms in the area covered by the sar images the ocean current analysis confirms that during the sar imaging times there were nios buoy measurements also show that moderate wind of 7 ms 1 existed 24 h prior to a sar observation and it diminished to 2 ms 1 in 6 h and remained very low for the next 18 h a condition ideal for producing nios

late quaternary history of the ventura mainland shelf california abstract the ventura mainland shelf off california provides an interesting example of sedimentary response to tectonic activity and eustatic sea level fluctuations during the late quaternary a network of 370 km of high resolution seismic reflection profiles provides the basis for the study the high local rates of uplift as well as local basin subsidence have resulted in two distinct styles of sedimentation a late pleistocene angular unconformity separates folded plio pleistocene strata from undeformed upper pleistocene and holocene strata on the northern shelf in contrast the southern shelf is characterized by a thick section of stacked progradational deltaic sequences containing a well preserved record of late quaternary sedimentation sediment overlying the unconformity north of the pitas point fault ranges from 10 to 40 m in thickness whereas the equivalent sequence in the adjacent southern shelf is 80 85 m thick the distribution of upper pleistocene and holocene deposits is controlled by structural features including the pitas point and oak ridge faults and the ventura avenue anticline as well as proximity to fluvial input from the santa clara and ventura rivers within upper pleistocene deposits a pair of buried marine terraces occur at depths of 33 and 50 m below present sea level b p s l terrace deposits consist of a basal coarse grained transgressive deposit which is transitional into a finer grained marine facies these deposits are associated with a period of aggradation during minor late wisconsinan sea level cycles deltaic deposits beneath the southern shelf 4 km north of hueneme submarine canyon suggest that the santa clara river debouched into the sea at this location during the late pleistocene the santa clara river shifted southward during the late wisconsinan and cut a large channel now buried near hueneme canyon this channel indicates that relative sea level was at least 113 m b p s l during the late wisconsinan a smaller channel indicates a fall in sea level to 46 m b p s l during the holocene the oak ridge fault displays a general increase in offset seaward across the shelf with a maximum vertical displacement of 17 m on the saugus upper pleistocene contact displacements on the pitas point fault increase shoreward attaining as much as 40 m of vertical displacement of the late pleistocene unconformity nearshore the pitas point fault vertically displaces the seafloor by 4 m

rates of delta progradation during highstands consequences for timing of deposition in deep marine systems estimated times required for 24 modern river systems to form a shelf edge delta range from 8 5 ka to 116 5 ka depending on fluvial sediment supply delta width shelf volume and shelf transport rates these values indicate that transport of sand into deep marine systems is likely to be significant during third order highstands of relative sea level factors such as shelf transport dynamics may slow delta progradation while submarine canyons cutting the shelf may reduce the time before deep marine deposition occurs interpreting ancient sand rich deep marine strata as lowstand deposits without sufficient palaeogeographic information may not therefore always be appropriate

effect of wind direction and incidence angle on polarimetric sar observations of slicked and unslicked sea surfaces abstract the objective of this paper is to investigate the dependency of oil spill observations in polarimetric sar data on imaging geometry i e on incidence angle and look direction relative to the wind the study is based on quad polarization data acquired by the uninhabited aerial vehicle synthetic aperture radar over experimental oil slicks under relatively high winds of 10 12 m s over an 8 hour period the data is collected over a wide range of incidence angles and alternates between looking upwind uw and downwind dw the unique time series enables a detailed study of the behavior of multipolarization parameters over clean sea and oil slicks under varying imaging geometry to be carried out for the first time for clean sea backscatter our findings are in agreement with previous studies showing decreasing backscatter as the incidence angle increases and from uw to dw with the highest sensitivity in the hh channel we also find similar variations in oil covered areas the results suggest that the oil slick backscatter is slightly more sensitive to the relative wind direction than the clean sea and higher oil sea damping ratios are found in dw than in uw cases particularly in the hh channel all multipolarization features investigated have some degree of dependency on imaging geometry the lowest sensitivities are found in the magnitude of the copolarization correlation coefficient the standard deviation of the copolarized phase difference the polarization difference the mean scattering angle and the entropy several features clearly change behavior when the signal approaches the sensor noise floor and we find that the measurements and derived parameters may be affected at even higher signal to noise ratio snr levels than previously proposed i e closer to 7 9 db above the sensor noise floor overall the polarization difference is clearly identified as the most interesting parameter for oil spill observation producing high oil sea contrast in addition to low sensitivity to imaging geometry the results show that both the relative wind direction and the incidence angle in combination with the snr should be taken into account when developing operational methods based on multipolarization sar data

a recent turbidity current event hueneme fan california reconstruction of flow properties a recent 100 yr old turbidite is described from hueneme fan california continental borderland dense sampling over the fan surface has allowed excellent delineation of the characteristics of this deposit it exhibits bouna de sequences and has a distinctly bimodal sandy silt grain size distribution through the use of generalized fluid dynamics equations it is possible to reconstruct original flow properties of the current which deposited this material the calculated velocities ranged from 10 90 cm s 1 and excess density above ambient seawater from 0 001 0 005 g cm 3 in the lower midfan and upper fan channel regions respectively height of the current ranged from 5 15 m on slopes from 1 5 to 0 15 a total of 107 m3 of sediment was deposited during 10 days the turbidity current is conjectured to have originated from direct river input during the floods of 1884 an older event is also described which has distinctly different properties and origins the grain sizes of this older deposit are much coarser and sedimentary structures suggest higher flow regimes this turbidite is conjectured to have been deposited from a higher density faster current thought to have been generated by slumping the need for a better understanding of the controls on the characteristics of turbidity currents and their effect on fan morphology is emphasized

late quaternary depositional systems and sea level change santa monica and san pedro basins california continental borderland a suite of seismic reflection data that provides different degrees of resolution and penetration was used to map the depositional systems that have developed in santa monica and san pedro basins during the late quaternary submarine fan growth particularly at the mouths of hueneme and redondo canyons has been the dominant mode of basin filling mass movement processes ranging from creep to large scale catastrophic slumping have been important locally in general large scale fan growth fits normark s model in which the suprafan is the primary locus of coarse sediment deposition smaller scale morphologic and depositional patterns on the hueneme and redondo fans e g distributary channels and coarse sediment concentrations basinward of the inner suprafan suggest that a significant amount of coarse sediment presently bypasses the suprafans however long distance coarse sediment transport was particularly pronounced during late wisconsinan lowstand of sea level and resulted in progradation of lower mid fan and lower fan deposits as sea level rose rapidly between 18 000 y b p and 10 000 y b p shelves trapped much of the sediment supply consequently rates of basin sedimentation decreased markedly and the area of fan developmen was restricted as the rate of shelf sedimentation decreased concomitantly with a decrease in the rate of sea level rise 10 000 y b p sediment transport to the basins was renewed and modern depositional patterns were established fan development also has been influenced by large scale mass movement extensive mid fan overbank flow and the consequent development of sediment waves deflection of turbidity currents by bathymetric obstacles and local tectonism correlations between sand layer characteristics and high resolution echo types for fan and basin plain deposits show trends similar to some of those observed in deep sea depositional environments however because santa monica and san pedro basins are small enclosed tectonically active basins that receive sediment from relatively large drainage areas proximal to distal changes in sand layer thickness abundance and frequency are less pronounced than those observed in deep sea environments

oil slick observation at low incidence angles in ku band on the 20 april 2010 the oil platform deep water horizon in the gulf of mexico suffered an explosion during the final phases of drilling an exploratory well as a result an oil film covered the sea surface area of several thousand square kilometers in the present paper the data of the ku band precipitation radar which operates at low incidence angles were used to explore the oil spill event the two scale model of the scattering surface was used to describe radar backscatter from the sea surface the algorithm for retrieval of normalized radar cross section at nadir and the total slope variance of large scale waves compared to the wavelength of electromagnetic wave 22 mm was developed for the precipitation radar swath it is shown that measurements at low incidence angles can be used for oil spill detection this is the first time that the dependence of mean square slope of large scale waves on wind speed has been obtained for oil slicks from ku band data and compared to mean square slope obtained by cox and munk from optical data

non annual laminations and expansion of anoxic basin floor conditions in santa monica basin california borderland over the past four centuries sediments from box cores in the deep portion of santa monica basin have been examined by x radiography and the upper 10 20 cm are characterized by laminations 1 5 mm in thickness age dating of 9 cores by 210pb analysis has shown that accumulation rates on the central basin floor have been remarkably constant during the past century averaging 16 0 0 4 mg cm2 yr densitometer analysis of the x radiography films from 7 cores and spectral analysis of the resulting time series indicates that most lamination couplets have a periodicity in the 3 7 year range a range matching that of the el nino southern oscillation periodicity the median periodicity appears to have decreased slightly during the past 3 centuries from 7 0 years during 200 300 yrs b p to 5 2 yrs during 0 100 yrs b p this trend could be due to a decreasing sedimentation rate an increasing forcing frequency or an increasingly faithful response of the basin in more recent years multiple processes have contributed to creation of the laminations in santa monica basin the principal factors appear to be 1 variations in porosity due to the relative abundance of organic filaments probably formed by beggiatoa mats and 2 compositional variations that reflect variations in carbonate lithogenous ratios and in grain size both of these are expected to respond to enso events the presence of near anoxic bottom waters has prevented bioturbation permitting laminations to be preserved basin bottom waters became nearly anoxic about 350 years ago at the onset of warming as the little ice age waned expansion of the near anoxic area during the past century may have been augmented by 20th century anthropogenic effects the style of these non annual laminations in santa monica basin matches that of the annual laminations in the adjacent santa barbara basin and demonstrates the need for caution in interpreting all laminations as representing annual varves

polarimetric analysis of compact polarimetry sar architectures for sea oil slick observation in this paper a theoretical and experimental analysis of polarimetric synthetic aperture radar sar architectures is undertaken for sea oil slick observation purposes reference is made to the conventional full polarimetric fp sar that is here contrasted with new generation polarimetric sar architectures known as compact polarimetric cp sar two cp modes are considered i e the hybrid polarity and 4 modes whose measurements are emulated from actual l and c band fp sar data polarimetric sea surface scattering is predicted according to an extended version of the bragg scattering model x bragg in order to point out the differences exhibited between fp and cp sar architectures and among cp sar modes theoretical predictions are then contrasted with experiments undertaken on actual polarimetric sar data collected over well known oil slicks and weak damping surfactants results confirm model prediction showing that differences mainly apply when polarimetric features are estimated over slick free sea surface using different sar architectures with the 4 mode behaving closer to fp sar although cp sar architectures measure only a subset of the fp information content they represent an interesting operational alternative for both detecting oil slicks and discriminating them from weak damping surfactants

depositional events in santa monica basin california borderland over the past five centuries the southern california coastal climate is characterized by decadal and generational floods that discharge one to three orders of magnitude more sediment than the average annual contribution these can produce turbidity currents directly or load the canyons and slopes with sediments that then may fail and form turbidity flows seismic activity is high on this transform margin and can trigger slope failures where slope sedimentation rates are high and sediments are unstable these events produce slope failures and slides and slumps in canyon heads which evolve into turbidity currents of sufficient volume to reach the adjacent margin basin floors such events occur at approximately century frequency this paper describes six basin floor turbidites that have been mapped in box cores sampling roughly the top 40 50 cm from the basin floor or santa monica basin in the california borderland these deposits were laid down during the past 500 years of record their depositional areas have been conservatively estimated to range from 500 to almost 1500 km2 and contain masses of sediment ranging from 10 000 000 to 100 000 000 tons this compares with a long term average annual terrigenous contribution rate of about 4 000 000 tons yr from the adjacent major streams although annual rates vary from 0 to 60 000 000 tons over the last century of record three of the six events have been related to two major floods 1884 6 1969 and to one major seismic event the mission earthquakes of 1822 1812 the older turbidites were deposited before european entry to the area and cannot be assigned to an historic event but from their size were probably seismically triggered and are the largest of the six events it is likely that other smaller events are masked by the more recent turbidites particularly in the area where box cores are dominantly composed of turbidites these features exhibit average outcrop thickness of 2 to 7 cm with maxima of the order of 10 cm thickness yet represent major events and significant volumes of sediment they also document that the two major sources for such events floods and seismic events produce deposits of very different mass and can probably be separated in the record on that basis thus the frequency of major floods and of major earthquakes in the region could be defined from study of such deposits in longer cores these deposits also provide examples of continued turbidity current activity to the basin floors at a time of high sea level this is contrary to the passive models for sequence stratigraphy depositional patterns

holocene sediment budgets for the basins of the california continental borderland abstract two holocene sediment budgets have been compiled for the california continental borderland the first detailed budget includes the six northern inshore and central basins that capture almost 40 of the total sediment input to the entire borderland in the second budget the data for the six basins has been added to estimates of accumulation for the remaining borderland area to produce a total regional budget of lower precision than the smaller six basin region natural river influx to the borderland approximates 13 1010 tons for the holocene epoch and biological input has been estimated at about 2 1010 tons eolian and ocean current influx have each been estimated at about 1 1010 tons in sum the total deposited volume for 104 yrs is about 14 1010 tons and the estimated total influx is of the order of 17 1010 tons which suggests that a net of 1 3 101010 tons for the holocene high sea level period the six high accumulation rate basins are located adjacent to the largest river sources the major zones of coastal upwelling and the main northern eddies of the california current these high accumulation sites are typically also areas where mass movement and fan development are localized the sediment accumulation rate is much larger than subsidence rate and flat floored basins are typical in contrast the southern and outer low accumulation basins are areas of draped sediment with accumulation rate less than subsidence rate and are the sites of penecontemporaneous deformation of the accumulating fine hemipelagic sediments few fans or major mass movements are seen significant sedimentation is mainly confined by topography to less than 20 of total margin area thus the moderate to low total sediment influx is amplified by the restricted receiving area to produce locally thick deposits of limited areal extent this pattern is characteristic of neogene southern california basins and illustrates that stratigraphic thickness is not a valid indicator of sediment influx

sea level and tectonic control of middle to late pleistocene turbidite systems in santa monica basin offshore california small turbidite systems offshore from southern california provide an opportunity to track sediment from river source through the turbidity current initiation process to ultimate deposition and to evaluate the impact of changing sea level and tectonics the santa monica basin is almost a closed system for terrigenous sediment input and is supplied principally from the santa clara river the hueneme fan is supplied directly by the river whereas the smaller mugu and dume fans are nourished by southward longshore drift this study of the late quaternary turbidite fill of the santa monica basin uses a dense grid of high resolution seismic reflection profiles tied to new radiocarbon ages for ocean drilling program odp site 1015 back to 32 ka over the last glacial cycle sedimentation rates in the distal part of santa monica basin averaged 2 3 mm yr 1 with increases at times of extreme relative sea level lowstand coarser grained mid fan lobes prograded into the basin from the hueneme mugu and dume fans at times of rapid sea level fall these pulses of coarse grained sediment resulted from river channel incision and delta cannibalization during the extreme lowstand of the last glacial maximum sediment delivery was concentrated on the hueneme fan with mean depositional rates of up to 13 mm yr 1 on the mid and upper fan during the marine isotope stage mis 2 transgression enhanced rates of sedimentation of 4 mm yr 1 occurred on the mugu and dume fans as a result of distributary switching and southward littoral drift providing nourishment to these fan systems longer term sediment delivery to santa monica basin was controlled by tectonics prior to mis 10 the anacapa ridge blocked the southward discharge of the santa clara river into the santa monica basin the pattern and distribution of turbidite sedimentation was strongly controlled by sea level through the rate of supply of coarse sediment and the style of initiation of turbidity currents these two factors appear to have been more important than the absolute position of sea level

detection of natural oil slicks in the nw gulf of mexico using modis imagery i we demonstrate the unique capability of the modis instruments in detecting oil slicks in an open ocean environment on 13 may 2006 in the nw gulf of mexico where water depth ranges from 50 to 2500 m one 250 m resolution modis image showed at least 164 surface slicks under sun glint glint reflectance l g ranged between 0 0001 and 0 06 sr 1 after discounting other possible causes we believe these are the result of natural seeps our analysis showed total coverage of 1900 km 2 with individual slicks varying in surface area 1 1 7 14 8 km 2 and length 19 2 12 4 km concurrent sar imagery showed similar area estimates to within 30 this estimate based on a single image is higher than earlier estimates from a database of multi date sar images for the same region inspection of 200 images for the month of may between 2000 and 2008 revealed similar slicks on at least 50 images on 2 june 2005 slicks were detected under sun glint with both negative contrast l g 0 05 sr 1 these slicks could not be detected in glint free modis images collected on the same day because of the near daily revisit and wide sun glint coverage e g 800 km e w between march and october at 25 n systematic and global application of the modis 250 m imagery can help locate natural seeps and improve estimates of seepage rates in the world s ocean

deep sea channel submarine yazoo system of the labrador sea a new deep water facies model the deep sea channel submarine yazoo system in the labrador sea consists of a major basin draining trunk channel the northwest atlantic mid ocean channel namoc with an interconnected basin wide network of tributary and satellite channels that are linked up with slope canyons the 3800 km long and up to 200 m deep namoc has asymmetrical levees rising up to 80 m above the adjacent flood plains and braid plains whereas the channel floor lies up to 100 m below the plains this limits major mid reach channel avulsion and permits the main channel to retain a relatively stable position over long periods of time tributary channels are denied entrance to the main channel by the high natural levees and are forced to flow parallel to the namoc for hundreds of kilometers in a fashion similar to yazoo type rivers on land the satellite channels east of the namoc form a submarine braid plain grain size fractionation into coarse to very coarse grained channel fill deposits and muddy spillover deposits on the levees is extreme for the main channel fractionation is min r for the shallow yazoo type and other tributary channels on the basin plain whose levees tend to be sandy nine depositional facies have been differentiated on the basis of piston cores and echo character in seismic profiles 1 deep channel fill 2 small scale slide slump facies on the walls of deep channels or canyons 3 spillover facies on the levees of the main channel 4 channel fill of shallow second order channels including yazoo type channels 5 levee facies of second order channels 6 submarine braid plain facies 7 debris flow deposits 8 contourite facies and 9 pelagic and hemipelagic sediments in contrast to the centrifugally diverging pattern of distributary channels of classical deep sea fan depositional systems the submarine drainage system of the namoc forms a centripetally converging channel pattern the submarine yazoos and other tributaries join a single trunk channel the system is multisourced by definition progressive proximal to distal merger of tributaries with the main trunk channel focuses the coarse grained facies along the basin axis this contrasts sharply with classical deep sea fans whose sands are being diffused distally in depositional lobes development of deep sea channel submarine yazoo systems is controlled by basin geometry and the number and intensity of sediment sources along the basin margins marginal seas or small ocean basins in the vicinity of waxing and waning major continental ice caps or actively rising mountain belts are ideal hosts for this kind of deep water turbidite system

holocene sea level curves for santa monica shelf california continental borderland a curve is constructed showing changes in sea level at the santa monica shelf over the past 18 000 years the curve is based on radiocarbon dates sedimentologic data and high resolution seismic stratigraphic analysis of late quaternary terrace deposits sea level was 117 meters below its present position about 18 000 years ago during the first 8000 years of the flandrian transgression sea level rose to at least 24 meters fell to about 46 meters and then rose to 20 meters all below present sea level subsequently sea level rose more slowly and without discernible interruption to its present position

contemporary channel levee systems in active borderland basin plains california continental borderland abstract long range large scale side scan gloria information other seismic reflection profiling studies and data from cores in the california continental borderland have defined active levee channel systems extending basinward from the lower fan of hueneme mugu submarine fan redondo submarine fan and santa cruz canyon fan in santa monica san pedro and santa cruz basins respectively the holocene distributaries have been created by a series of turbidity current events these distributaries range in length from 10 25 km and are wide 2 5 km and low relief 1 10 m in their distal parts they are also active conduits for nepheloid flows distributions of sedimentological parameters typically mimic the pattern of levee channel systems organic carbon and biogenic carbonate content roughly outline the systems channels are incised in the upper to middle fan areas and become constructional leveed channels in the lower fan and basin plain as the channel gradient adjusts to maintain a graded profile thus sediment gravity flows are generally confined to channels in the upper fan zones but deposit both channelized and over bank deposits on the lower fan and basin floor the deposits show that the canyon fan activity has continued during a rising sea level phase it is evident that canyon headward erosion rates have been equal to or greater than the transgression rate and that the canyon fan systems have remained linked with their sediment sources frequency of events was probably higher and volumes of the events were often larger during the glacially lowered sea level episodes however turbidity currents of sufficient volume to reach the basin floors continue to occur at century or multi century intervals as one progresses headward in each system the number of flows per length of core increases small flows that do not pass beyond the distributaries are much more frequent and may be decadal in frequency or even more frequent in the santa monica basin system these california borderland basins are probably typical of narrow active margins where rate of lateral sea level transgression is less than or equal to the rate of canyon headward erosion the canyons maintain connections with sediment sources during sea level rise and the systems therefore are active during the entire sea level cycle thus sediment supply is not a simple function of eustacy this contrasts with the simplified sequence model developed on passive margins where canyons turn off as sea level rises

classification of ocean surface slicks in simulated hybrid polarimetric sar data in this paper we consider hybrid polarimetric synthetic aperture radar sar data of ocean surface slicks and hypothesize that we can design a system that is able to discriminate between mineral oil plant oil and clean sea we focus particularly on challenges related to data set shift between the training and test data in sar images of ocean surfaces data set shift is typically caused by the variation of wind level and incident angles that directly impact the backscatter intensities we evaluate several classifiers domain adaptation strategies and multilooking strategies hybrid polarimetric sar data are simulated from the radarsat 2 quad pol images the proposed methodology was trained using five different radarsat 2 quad pol images that cover slicks of known types and tested on 10 different radarsat 2 quad pol images covering various ocean surface slicks the results show that we were able to a large degree to classify the type of various surface slicks the average classification accuracy obtained from cross validation on the training data was 91 the results also show that we were able to correctly classify surface slick in new test images even if the wind surface and acquisition conditions were different from the training images we conclude that hybrid polarity is an attractive mode for future enhanced sar based oil spill monitoring however to fully exploit the imaging mode single look complex images are necessary

rain footprints on c band synthetic aperture radar images of the ocean revisited abstract it is well known that rain leaves footprints on the sea surface that sometimes become visible on synthetic aperture radar sar images rain cells can easily be detected on sar images at all radar frequencies when they are associated with a downdraft pattern but rain cells are not always associated with downdraft and rain can also occur in other forms as stratified rain rain bands and squall lines it turns out that radar signatures of rain at c band are much more complex than at l or x band radar and that it is particularly difficult to identify unambiguously rain events on c band sar images acquired over the ocean this is because c band lies in the transition region where raindrops impinging onto the sea surface can increase usually or decrease the backscattered radar power and where volume scattering and attenuation by rain drops in the atmosphere are not always negligible at very high rain rates in order to get an insight into the physical mechanisms causing the c band radar signatures of rain we first revisit results obtained from historic laboratory and field experiments and multi frequency multi polarization sar data acquired during the sir c x sar spaceshuttle mission in 1994 then we analyze several c band sar images acquired by the european satellites envisat and sentinel 1a and the canadian satellite radarsat 2 and compare them whenever possible with quasi coincident and collocated weather radar images the observational data show that at low to medium rain rates the main physical mechanism causing c band radar signatures of rain is bragg scattering at ring waves generated by the rain drops impinging onto the sea surface which increase the radar backscatter however areas of increased radar backscatter are often accompanied by adjacent areas of decreased radar backscatter which is due to attenuation of the bragg waves by turbulence also generated by the impinging rain drops furthermore we present a full polarimetric radarsat 2 sar image of a rain cell together with a polarimetric decomposition analysis which shows that the c band radar signature of a rain cell is caused by surface scattering the observation show that radar signatures of rain cells often contain segments where the co polarized as well the cross polarized radar backscatter are strongly enhanced which indicates non bragg scattering contributions to the scattering process furthermore the polarimetric decomposition analysis shows that the c band radar signature of a rain cell is dominated by surface scattering possible mechanisms like scattering at splash products are discussed whether the normalized radar cross section nrcs due to rain is increased or decreased depends on rain rate wind speed incidence angle and history of the rain event at low to moderate wind speeds 10 m s 1 and low to high rain rates but

characterization of marine surface slicks by radarsat 2 multipolarization features in this paper we study surface slick characterization in polarimetric c band synthetic aperture radar sar data the objective is to identify the most powerful multipolarization sar descriptors for mineral oil spill versus biogenic slick discrimination a systematic comparison of eight well known multipolarization features is provided the analysis is performed on data that we collected during a large scale oil spill exercise at the frigg field situated northwest of stavanger in june 2011 controlled oil spills and simulated look alikes were simultaneously captured within fine quad polarization radarsat 2 acquisitions during this experiment multipolarization features derived from only the copolarized complex scattering coefficients are explored we find that the two most powerful multipolarization features extracted from this data set are the geometric intensity measuring the combined intensity based on the determinant of the coherency matrix and the real part of the copolarization cross product which is related to the scattering behavior of the target we show that these two features can distinguish between the simulated biogenic slicks and mineral oil types such as balder and oseberg blend and that the discriminative power seems to be persistent with time

compact polarimetric synthetic aperture radar for marine oil platform and slick detection compact polarimetric cp synthetic aperture radar sar can provide ocean surface observations with large coverage swath and abundant polarimetric scattering information these distinctive characteristics make cp sar a potential tool for operational monitoring oil slicks and oil platforms overcoming the shortcomings of small spatial coverage by the traditional quad polarization quad pol sar in this paper we use the radarsat 2 c band quad pol sar data to generate cp covariance matrix elements and subsequently construct pseudoquad pol backscatter coefficients using two cp reconstruction algorithms to evaluate cp sar s applications in detection of oil slicks and oil platforms the reconstructed co and cross polarization data show good agreement with original radar observations acquired at different incidence angles and wind speeds furthermore we develop an unsupervised classification method using the relative phase a logical scalar threshold that separates odd and multiple scattering events as an indicator to discriminate oil slicks and platforms from clean ocean waters the relative phase is positive for clean ocean surfaces where odd scattering is dominant but negative for oil platforms and oil slick covered areas associated with multiple scattering the detections of oil spills and oil platforms are validated against known oil platform geographic positions and optical aircraft surveys of the oil slicks the proposed method provides a promising technique to detect oil slicks and oil platforms from cp imaging mode sar data i e as may be acquired by the risat 1 alos 2 and the future radarsat constellation mission

late cenozoic sedimentation in california continental borderland basins as revealed by seismic facies analysis the california continental borderland began to form during late miocene time only the latest miocene and younger sediments are ponded in the contemporary basins upper miocene strata are characterized by widespread diatomaceous deposits that conformably drape all of the underlying topographic irregularities the pliocene quaternary sediments occur as flat lying ponded clastic sequences that fill the contemporary basins a seismic facies analysis has defined facies patterns in the pliocene quaternary basin fill sequences of each basin in the offshore basins patton tanner santa cruz and san nicolas fine grained mass flow and hemipelagic sediments derived from the local insular sources dominate the basin fill sequences santa catalina basin is a transitional basin filled with fine grained turbidites and hemipelagic sediments derived from both continental and local insular sources the nearshore basins santa barbara santa monica and san pedro basins and san diego trough are filled by thick sequences of continental sediments that form prominent deep sea fans the borderland was dominated by biogenic pelagic sedimentation in the late miocene and by detrital sediment gravity flow deposition in the pliocene and quaternary accumulation rates estimated from pliocene quaternary sediment thickness for each basin show that in the offshore basins as well as in san diego trough rates have remained fairly constant since the pliocene in contrast the nearshore basins exhibit an increasing rate of accumulation versus time that is related to the progradation of continent derived sediments outer and intermediate basin accumulation data indicate decreasing contributions with time from offshore highs because of erosion and regional subsidence intermediate basins show an increase in mass wasting deposits slope facies with time which is the result of increasing fine suspension slope deposition and eventual failure

flow separation berms downstream of a hydraulic jump in a bedrock channel abstract the first direct observation of the development of lateral gravel berms associated with hydraulic jumps in bedrock channels is reported cobbles and pebbles were observed being swept through jumps and deposited in the tranquil flow immediately downstream and either side of the v shaped shock waves field measurements of jumps and geometry current speed and water depth are found to be consistent both with laboratory data and theoretical considerations the deposits have significance in constraining flood palaeoflow reconstructions as the presence of berms determines the former location of hydraulic jumps whilst the angle subtended by the berm crestline with respect to a regular bankline may be used to estimate the froude number of the flow

the first decade of gloria in 10 years of operation gloria has been used on 26 cruises and has inonified more than 1 of the ocean floor the paper reviews the scientific achievements of this new tool and assesses the contributions which it has made to understanding the geological features and the processes creating them a complete bibliography of gloria papers is included in the references and the best examples of sonographs obtained over different terrain are illustrated

measurement of ocean surface slopes and wave spectra using polarimetric sar image data abstract methods have been investigated which use fully polarimetric synthetic aperture radar sar image data to measure ocean slopes and wave spectra independent techniques have been developed to measure wave slopes in the sar azimuth and range directions the azimuth slope technique in particular is a more direct measurement than conventional intensity based backscatter cross section measurements in the azimuth direction wave induced perturbations of the polarimetric orientation angle are used to sense the wave slopes in the range direction a new technique involving the alpha parameter from the cloude pottier h a entropy anisotropy and averaged alpha polarimetric scattering decomposition theorem is used to measure slopes both measurement types are sensitive to ocean wave slopes and are directional taken together they form a means of using polarimetric sar polsar image data to make complete measurements of either ocean wave slopes or directional wave spectra these measurements must still contend with fundamental nonlinearities in the sar image processing i e azimuth direction velocity bunching that are due to wave velocity and acceleration effects nasa jpl airsar l and p band data from california coastal waters were used in the studies wave parameters measured using the new methods are compared with those developed using both conventional sar intensity based methods and with in situ noaa national data center buoy measurement products

the geological setting of santa monica and san pedro basins california continental borderland the california continental borderland s present configuration dates from about 4 to 5 106 years before present bp and is the most recent of several configuration of the southern california margin that have evolved after the north america plate over rode the east pacific rise about 30 106 years ago the present morphology is a series of two to three northwest southeast trending rows of depressions separated by banks and insular ridges two inner basins santa monica and san pedro have been the site for the california basin study cabs funded by the us department of energy the santa monica and san pedro basins contain post miocene sediment thicknesses of about 2 5 and 1 5 km respectively during the holocene past 10 000 years about 10 12m have accumulated the sediment entered the basin by one or a combination of processes including particle infall mainly as bioaggregates from surface waters from nepheloid plumes surface mid depth and near bottom from turbidity currents mass movements and to a very minor degree direct precipitation in santa monica basin during the last century particle infall nepheloid plume transport have been the most common processes the former process has been dominant in thecentral basin at water depths from 900 945m where characteristic silt clay is found with a typical mean particle diameter of about 0 0006mm standard deviation 2 skewness near zero kurtosis is typically 2 platykurtic these values indicate broad near log normal particle size distributions the calcium carbonate content averages about 10 and organic carbon about 4 surficial sediment bulk densities are 1 1 1 2 and accumulation rates range from 16 30mg cm 2yr1 in this central fine deposit bottom water oxygen contents are at or below 0 1 ml 1 1 so that bioturbation is inhibited thus preserving the primary sedimentary stratification there appear to be annual varves but the laminae couplets are not simple wet dry season pairs their formation is related to longer period climatic events el nino cycle of 3 to 4 years is dominant and is also affected by aperiodic bottom water flushing events the anoxic zone of bottom water has expanded over the past 300 to 350 years from a samll area in the northeastern basin floor ca 120km2 at 300 years bp and now covers most of the basin floor below depths of about 850m 1290km2 this expansion may have been primarily relaed to ocean circulation rate changes following the little ice age but is also likely to have been strongly affected by subsequent major changes in the natural drainages post european colonization the bottom water oxygen contents must also reflect the introduction of oxidizable pollutants coincident with the shift to agricultural mission era and then to urban use late 19th century to present of the adjacent mainland such localized effects are also suggested by the contrasting very large increases in the area of low oxygen bottom water in santa monica basin relative to the minimal changes in the area of anoxia in santa barbara basin over the same period and the lack of such zone in san pedro basin in the san pedro basin the bottom waters have remained dysaerobic so its sediments are bioturbated and preserve little or no evidence of primary stratification dumping of oil drilling muds and cuttings during the couple of decades prior to 1970 has left a surficial deposit ranging from 1 to 15cm in thickness forming a bull s eye isopach pattern as seen in radiographs bottom water oxygen content is usually 0 2ml o21 1 bottom infauna and epifauna are sparse central basin floor sediments water depths 800m of san pedro basin have textural characteristics similar to those of santa monica basin with distal basin floor surficial sediments being deposited primarily by particle infall and nepheloid flow at the present time mean diameters 0 006mm standard deviation 2 skewness 0 and kurtosis 2 platykurtic calcium carbonate content averages 8 10 and organic carbon is about 4 an estimate of the contemporary sedimentation rate was determined for a single box core of 25 29mg cm 2 yr1 from the central basin near the present distributary margin it cannot be considered necessarily to be representative mixing is indicated by the data an important climatic factor is the alternation of multi year wet and dry periods the california basin study was conducted during an extended dry period of low river discharge this undoubtedly will have affected the conclusions of the study related to sediment water interactions and pollutant transport by suspended clays