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  • Journal article
    Busby CJ, Hagan JC, Putirka K, Pluhar CJ, Gans PB, Wagner DL, Rood D, DeOreo SB, Skilling Iet al., 2008,

    The ancestral cascades arc: Cenozoic evolution of the central Sierra Nevada (California) and the birth of the new plate boundary

    , Special Paper of the Geological Society of America, Vol: 438, Pages: 331-378, ISSN: 0072-1077

    We integrate new stratigraphic, structural, geochemical, geochronological, and magnetostratigraphic data on Cenozoic volcanic rocks in the central Sierra Nevada to arrive at closely inter-related new models for: (1) the paleogeography of the ancestral Cascades arc, (2) the stratigraphic record of uplift events in the Sierra Nevada, (3) the tectonic controls on volcanic styles and compositions in the arc, and (4) the birth of a new plate margin. Previous workers have assumed that the ancestral Cascades arc consisted of stratovolcanoes, similar to the modern Cascades arc, but we suggest that the arc was composed largely of numerous, very small centers, where magmas frequently leaked up strands of the Sierran frontal fault zone. These small centers erupted to produce andesite lava domes that collapsed to produce block-and-ash flows, which were reworked into paleocanyons as volcanic debris flows and streamflow deposits. Where intrusions rose up through water-saturated paleocanyon fill, they formed peperite complexes that were commonly destabilized to form debris flows. Paleocanyons that were cut into Cretaceous bedrock and filled with Oligocene to late Miocene strata not only provide a stratigraphic record of the ancestral Cascades arc volcanism, but also deep unconformities within them record tectonic events. Preliminary correlation of newly mapped unconformities and new geochronological, magnetostratigraphic, and structural data allow us to propose three episodes of Cenozoic uplift that may correspond to (1) early Miocene onset of arc magmatism (ca. 15 Ma), (2) middle Miocene onset of Basin and Range faulting (ca. 10 Ma), and (3) late Miocene arrival of the triple junction (ca. 6 Ma), perhaps coinciding with a second episode of rapid extension on the range front. Oligocene ignimbrites, which erupted from calderas in central Nevada and filled Sierran paleocanyons, were deeply eroded during the early Miocene uplift event. The middle Miocene event is recorded by growth f

  • Journal article
    Jonoud S, Jackson MD, 2008,

    New criteria for the validity of steady-state upscaling

    , TRANSPORT IN POROUS MEDIA, Vol: 71, Pages: 53-73, ISSN: 0169-3913
  • Journal article
    Burberry CM, Cosgrove JW, Liu JG, 2008,

    Spatial arrangement of fold types in the Zagros Simply Folded Belt, Iran, indicated by landform morphology and drainage pattern characteristics

    , JOURNAL OF MAPS, Vol: 4, Pages: 417-430, ISSN: 1744-5647
  • Conference paper
    Barreto D, O'Sullivan C, Zdravkovic L, 2008,

    Specimen generation approaches for DEM simulations

    , 4th International Symposium on Deformation Characteristics of Geomaterials, Publisher: I O S PRESS, Pages: 901-906
  • Journal article
    Kontoe S, Zdravkovic L, Potts DM, Menkiti COet al., 2008,

    Case study on seismic tunnel response

    , Canadian Geotechnical Journal, Vol: 45, Pages: 1743-1764

    This paper presents a case study of the Bolu highway twin tunnels that experienced a wide range of damage during the 1999 Duzce earthquake in Turkey. Attention is focused on a particular section of the left tunnel that was still under construction when the earthquake struck and that experienced extensive damage during the seismic event. Static and dynamic plane strain finite element (FE) analyses were undertaken to investigate the seismic tunnel response at two sections and to compare the results with the post-earthquake field observations. The predicted maximum total hoop stress during the earthquake exceeds the strength of shotcrete in the examined section. The occurrence of lining failure and the predicted failure mechanism compare very favourably with field observations. The results of the dynamic FE analyses are also compared with those obtain by simplified methodologies (i.e. two analytical elastic solutions and quasi-static elasto-plastic FE analyses). For this example, the quasi-static racking analysis gave thrust and bending moment distributions around the lining that differed significantly from those obtained from full dynamic analyses. However, the resulting hoop stress distributions were in reasonable agreement.

  • Journal article
    Stafford PJ, Pettinga JR, Berrill JB, 2008,

    Seismic source identification and characterisation for probabilistic seismic hazard analyses conducted in the Buller-NW Nelson region, South Island, New Zealand

    , Journal of Seismology, Vol: 12, Pages: 477-498, ISSN: 1383-4649
  • Conference paper
    Taborda D, Zdravkovic L, Kontoe S, Potts DMet al., 2008,

    Modelling cyclic pile response using the Finite Element Method

    , 8th International Conference on the Application of Stress-Wave Theory to Piles, Pages: 327-333
  • Journal article
    Gomes JLMA, Pain CC, Eaton MD, Piggott MD, Goddard AJH, Ziver AK, Yamane Y, de Oliveira CREet al., 2008,

    Investigation of nuclear criticality within a powder using coupled neutronics and thermofluids

    , Annals of Nuclear Engineering, Vol: 35, Pages: 2073-2093
  • Book chapter
    Piggott MD, Pain CC, Gorman GJ, 2008,

    Unstructured adaptive meshes for ocean modeling

    , Ocean modeling in an eddying regime, Editors: Hecht, Hasumi, Hecht, Hasumi, Publisher: Amer Geophysical Union, Pages: 383-408, ISBN: 9780875904429
  • Journal article
    van Reeuwijk M, Jonker HJJ, Hanjalic K, 2008,

    Wind and boundary layers in Rayleigh-Benard convection. I. Analysis and modeling

    , PHYS REV E, Vol: 77
  • Journal article
    Crowley H, Bommer JJ, Stafford PJ, 2008,

    Recent developments in the treatment of ground-motion variability in earthquake loss models

    , Journal of Earthquake Engineering, Vol: 12, Pages: 71-80, ISSN: 1363-2469
  • Journal article
    Stafford PJ, 2008,

    Conditional Prediction of Absolute Durations

    , Bulletin of the Seismological Society of America, Vol: 98, Pages: 1588-1594
  • Journal article
    Attal M, Tucker GE, Whittaker AC, Cowie PA, Roberts GPet al., 2008,

    Modelling fluvial incision and transient landscape evolution: influence of dynamic channel adjustment

    , JOURNAL OF GEOPHYSICAL RESEARCH, Vol: 113
  • Journal article
    Crowley H, Stafford PJ, Bommer JJ, 2008,

    Can earthquake loss models be validated using field observations?

    , Journal of Earthquake Engineering, Vol: 12, Pages: 1078-1104
  • Journal article
    Verdoold J, van Reeuwijk M, Tummers MJ, Jonker HJJ, Hanjalic Ket al., 2008,

    Spectral analysis of boundary layers in Rayleigh-Benard convection

    , PHYS REV E, Vol: 77
  • Journal article
    Kontoe S, Zdravkovic L, Potts DM, 2008,

    The Domain Reduction Method for dynamic coupled consolidation problems in geotechnical engineering

    , International Journal for Numerical and Analytical Methods in Geomechanics, Vol: 32, Pages: 659-680
  • Conference paper
    Kontoe S, Zdravkovic L, Potts DM, 2008,

    The generalised-alpha algorithm for dynamic coupled consolidation problems in geotechnical engineering

    , 12th International Conference of International Association for Computer Methods and Advances in Geomechanics (IACMAG), Pages: 1449-1558
  • Journal article
    saunders J, jackson M, pain C, 2008,

    Fluid flow monitoring in oilfields using downhole measurements of electrokinetic potential

    , Geophysics, Vol: 73, Pages: E165-E180

    Downhole measurements of electrokinetic potential are a promising new technology for hydrocarbon reservoir monitoring. Using a 3Dfinite-element model combining both multiphase flow and electrokinetic components, we investigated the behavior of electrokinetic (streaming) potential during oil production in a range of reservoir environments. We found that streaming-potential signals originate at fluid fronts and at geologic boundaries where fluid saturation changes. As water encroaches on an oil production well, the streaming-potential signal associated with the water front encompasses the well even when the front is up to 100 m away, so the potential measured at the well starts to change significantly relative to a distant reference electrode. Variations in the geometry of the encroaching water front can be characterized using an array of electrodes positioned along the well, but a good understanding of the local reservoir geology is required to identify signals caused by the front. The streaming potential measured at a well is maximized in low-permeability reservoirs produced at a high rate and in thick reservoirs with low shale content. However, considerable uncertainties remain, particularly relating to the nature of electrokinetic coupling at high salinity and during multiphase flow. Our results suggest that the streaming potential at low salinity (10^-3–10^-4 mol/L) is large (100–1000 mV) but might become too small to resolve (<0.1) mV at high salinity (0.5–2 mol/L), depending on how the available data for the electrokinetic coupling at low salinity are extrapolated into the high-salinity domain. More work remains to determine the behavior of electrokinetic coupling and therefore the utility of this technique at high salinity.

  • Conference paper
    van Reeuwijk M, Mathias SA, Simmons CT, Ward JDet al., 2008,

    Improving the worthiness of the Elder problem as a benchmark for buoyancy driven convection models

    , Virtual Conference on Climate Change and CO2 Storage, Publisher: Nature Precedings
  • Journal article
    van Reeuwijk M, Jonker HJJ, Hanjalic K, 2008,

    Wind and boundary layers in Rayleigh-Benard convection. II. Boundary layer character and scaling

    , PHYS REV E, Vol: 77

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