Source Specific Station Corrections for Regional Phases at Fennoscandian Stations

—?The IASPEI91 global travel-time curves are used as the default for event location at the Prototype International Data Center (PIDC). In order to improve event location, a 1-D Baltic travel-time model was implemented at the PIDC in 1997 for locating events using regional phases from Fennoscandian stations. Where a single model is insufficient for characterizing the regional geology, path-dependent corrections, or Source Specific Station Corrections (SSSCs), are more appropriate for event locations. We have developed SSSCs for regional phases at the Fennoscandian stations by interpolating travel times through different 1-D models. SSSCs for stations NRIS and SPITS are also derived, given the fact that paths from both stations to high latitude events are within the Fennoscandia regionalization as Baltic.¶Validation testing of the SSSCs demonstrates that using SSSCs in event location is superior to not using SSSCs, a nd, in most cases, to using the 1-D model directly when locating events. For a ground-truth data set which includes events in the Baltic Shield with location accuracy better than 2?km, the average improvement in location due to SSSCs is 9?km, and the median coverage ellipse is reduced by 2710?km² (from 3830 to 1120?km²). These results are similar to those obtained using the 1-D Baltic model. For a CEB (Calibration Event Bulletin) data set which includes events along the North Atlantic oceanic ridge and in central/southern Europe, using SSSCs the ridge events move closer to the ridge axis, and the European events move closer to CEB locations than 1-D Baltic locations. For a constrained JHD (Joint Hypocenter Determination) data set of events in the Novaya Zemlya region, when using SSSCs or the 1-D Baltic model, relative to the JHD locations mislocations are less or similar to those without SSSCs. All coverage ellipses are smaller but sti ll contain the JHD solutions.¶Our SSSCs are strongly dependent on the 1-D regional models and regionalization. Future development in 1-D velocity models and travel-time curves should improve such SSSCs, event locations, and uncertainties. It is hoped that the implementation and demonstration of SSSCs in the PIDC software will encourage these further developments. These SSSCs were implemented at the PIDC for Reviewed Event Bulletin (REB) location in April 1999.     

Small ice cap instability in the presence of fluctuations

Phenomena associated with small ice cap instability (SICI) are investigated using a general circulation model (GCM: NCAR Community Climate Model version 0) and a noise-forced nonlinear energy balance model (EBM). Both make use of idealized boundary conditions consisting of an all-land planet without topography and mean annual insolation. Ice is prescribed to exist on surface areas for which the instantaneous temperature lies below freezing. The adjustable parameters of the EBM were chosen to match the GCM solutions. For the regions in parameter space where SICI might occur we do not find the corresponding icefree steady state solution with the GCM. Our simulations with the EBM show that SICI phenomena in the presence of fluctuations are strongly dependent on the amplitude of the noise forcing. When the strength of noise forcing is adjusted to match the fluctuations in the GCM, we do not find a SICI in the EBM. With weaker levels of forcing the SICI reappears. In all cases steady stable ice caps smaller than a critical size are not found to exist.     

The paleolimnology of a small waterbody in the Pocono Mountains of Pennsylvania,USA: reconstructing 19th–20th century specific conductivity trends in relation to changing land use

Remains of scaled chrysophytes, magnetic minerals and pollen were used to analyze the recent paleolimnological history of a small lake, Lake Waynewood, in the Pocono Mountains of Pennsylvania. Important shifts in all three variables were observed over the 133 years represented by the core. The most significant changes occurred near the turn of the century when the watershed was heavily logged. Before the logging event, species such asSynura sphagnicola, S. spinosa, Mallomonas galeiformis andM. duerrschmidtiae were co-dominant members of the flora. Subsequent to the deforestation of the watershed other taxa, includingM. crassisquama, M. caudata andS. petersenii, increased in relative importance. Concurrent with changes in the scaled chrysophytes was a six-fold increase in the concentrations of magnetic material, presumably the result of increased erosion caused by the logging. Changes in pollen grains also correlate well with the onset of the deforestation event. The scaled chrysophyte inferred specific conductivity of the lake has more than tripled, with the primary increase occurring concurrent with the commencement of logging and the increase in magnetic mineral material. The effects of other human-related disturbances are also discussed.     

Résultats préliminaires sur la sédimentation pélagique de l'Atlantique tropical au Crétacé et au Tertiaire (plateau de Demerara,Leg ODP 207)

Five sites located on a bathymetric transect of the distal Demerara Rise were studied by ODP Leg 207. Albian sediments of essentially terrigenous nature (clay, siltstone, sandstone) are the oldest drilled stratigraphic levels and form apparently the top of the synrift sequence. They are overlain by Cenomanian to Santonian finely laminated black shales, rich in organic matter of marine origin, which accumulated on a thermally subsiding ramp. Early Campanian hiatuses are thought to be the result of final disjunction of Demerara Rise (South America) from Africa and the onset of deep water communication between the two Atlantic basins (south and central). The overlying Uppermost Cretaceous–Oligocene chalk includes rich and diversified calcareous plankton assemblages, as well as two radiolarian-rich intervals (Late Campanian and Middle Eocene). A complex erosional surface developed during the Late Oligocene–Early Miocene. Sedimentation was impeded since then on the intermediate and deep sites of Demerara Rise, possibly due to the action of deep submarine currents. To cite this article: T. Danelian et al., C. R. Geoscience 337 (2005).     

To the market and back: Housing policy and state housing in New Zealand

Housing policy in New Zealand has traditionally been characterised by significant market intervention in support of home ownership and a residual state housing rental sector. Within the context of dramatic social welfare reforms in the 1990s, a set of radical housing reforms was introduced that profoundly transformed the role of the state in the housing system. Key elements of the reforms included the creation of a profit-oriented company to manage state rentals, a move to market rents in the state sector and the introduction of an accommodation supplement. This paper examines the underlying rationale and impacts of the reforms focusing on issues of privatisation, tenant turnover, affordability and tenant protest. Having examined the ongoing problems engendered by these reforms the paper reviews more recent political and legislative reforms that were sought to reassert the state's traditional position within the New Zealand housing market. This revised version was published online in July 2006 with corrections to the Cover Date.     

Privatization of rural industry and de facto urbanization from below in southern Jiangsu, China

At the heart of China’s economic transformation from plan to market is the institutional rearrangement of the ownership of property rights. Privatization of collectively owned township and village enterprises (TVEs) in recent years has significantly changed the rural economy and affected small town development in China. Located mainly in villages and small towns and producing 62% of the total industrial output in Jiangsu in 1994, TVEs played a crucial role in southern Jiangsu (Sunan)’s economic development and urbanization, giving rise to the well-known “Sunan model” of regional development during the 1980s. Since the mid-1990s, ownership transition (zhuanzhi) of the TVEs from collective to private in Sunan has altered the nature of the regional economy and the pattern of small town development. The privatization of TVEs in Sunan has been so pervasive that it can be seen as the “second industrial divide” in the region’s economy. This paper traces the evolution of ownership reform in Sunan’s rural industries leading to the current phase of privatization and analyzes the effects of privatization on de facto urbanization from below in Sunan. Given the importance of privatization, continuous scholarly monitoring of its relationship to regional economic development and urbanization from below is necessary.     

Flood Management Strategy for the Upper and Middle Odra River Basin: Feasibility Study of Raciborz Reservoir

The river Odra, which rises in the Czech Republic and disgorges into the Baltic, suffered an extreme flood in July 1997 which was responsible for the loss of 55 lives and over a billion dollars worth of damage in southern Poland. The return period of the flood is variously estimated between 250 and 1000 years. The paper describes the hydrological and hydraulic studies undertaken for a flood reservoir (storage capacity is approximately 180,000,000 m³) to be constructed on the River Odra just upstream the ancient town of Raciborz, on the border between Poland and Czech Republic. These studies included the hydrodynamic modelling of a 220 km stretch of the river down to the city of Wroclaw where most of the damage occurred, flood damage analysis with and without the proposed reservoir, sensitivity analysis of operating rules for Nysa reservoirs and improvement of flood control capacity of existing channels and polders. Cost-benefits analysis, environmental impact assessments and resettlement plans, in addition to the engineering studies of the dam itself, were also carried out during the project stage but have not been included in the present paper.     

The influence of episodic events on transport of striped bass eggs to the estuarine turbidity maximum nursery area

The estuarine turbidity maximum (ETM) is an important nursery area for anadromous fish where early-life stages can be retained in high prey concentrations and favorable salinities. Episodic freshwater flow and wind events could influence the transport of striped bass (Morone saxatilis) eggs to the ETM. This hypothesis was evaluated with regression analysis of observational data and with a coupled biological-physical model of a semi-idealized upper Chesapeake Bay driven by observed wind and freshwater flow. A particle-tracking model was constructed within a numerical circulation model (Princeton Ocean Model) to simulate the transport of fish eggs in a 3-dimensional flow field. Particles with the sinking speed of striped bass eggs were released up-estuary of the salt front in both 2-d event-scale and 60-d seasonal-scale scenarios. In event scenarios, egg-like particles with observed specific gravities (densities) of striped bass eggs were transported to the optimum ETM nursery area after 2 d, the striped bass egg-stage duration. Wind events and pulses in river discharge decreased the number of egg-like particles transported to the ETM area by 20.9% and 13.2%, respectively, compared to nonevent conditions. In seasonal scenarios, particle delivery to the ETM depended upon the timing of the release of egg-like particles. The number of particles transported to the ETM area decreased when particles were released before and during wind and river pulse events. Particle delivery to the ETM area was enhanced when the salt front was moving up-estuary after river pulse events and as base river flow receded over the spawning season. Model results suggest that the timing of striped bass spawning in relation to pulsed events may have a negative (before or during events) or positive (after river flow events) effect on egg transport. Spawning after river flow events may promote early-stage survival by taking advantage of improved transport, enhanced turbidity refuge, and elevated prey production that may occur after river pulse events. In multiple regression analysis of observed data, mean spring freshwater flow rates and the number of pulsed freshwater flow events during the striped bass spawning season explained 71% of the variability in striped bass juvenile abundance in upper Chesapeake Bay from 1986 to 2002. Positive parameter estimates for these effects support the hypothesis that pulsed freshwater flow events, coupled with spawning after the events, may enhance striped bass early-stage survival. Results suggest that episodic events may have an important role in controlling fish recruitment.     

Chemical variability in the Sacramento River and in Northern San Francisco Bay

Specific conductance and concentrations of alkalinity, dissolved silica, nitrate, and ammonium were measured daily in the Sacramento River flow to northern San Francisco Bay during the rainfall seasons of 1983 and 1984 (high flow) and during late summer and early fall of 1984 (low flow). Flow and concentrations of chemical species varied in response to storm events during high flow, but flow was more variable than concentrations of chemical species. Runoff from agriculturally developed areas appeared to increase specific conductance and concentrations of alkalinity during high flow. During low flow, inputs of agricultural tailwaters caused variations in concentrations of alkalinity and dissolved silica. Dilution of municipal waste by river flow caused variability in concentrations of ammonium during both high flow and low flow. Distributions of alkalinity, dissolved silica, nitrate, and ammonium were measured in northern San Francisco Bay during late summer and fall of 1984. Changes in distributions of alkalinity in the estuary were caused by variations in alkalinity in the Sacramento River. Changes in distributions of dissolved silica, nitrate, and ammonium appeared to be primarily related to variations in supply by the river and removal by phytoplankton. Effects of removal by phytoplankton were large for ammonium and dissolved silica, but appeared relatively small for nitrate.     

Contact metamorphism/hydrothermal alteration of Tertiary basalts from the Isle of Skye,northwest Scotland

Alkali olivine basalts from Skye were simultaneously contact metamorphosed by Tertiary gabbro and granite intrusions and altered by the hydrothermal convection system that the plutons induced. Four metamorphic zones were mapped around the plutons. Furthest from the intrusions, in the primary olivine zone, metabasalts are composed of combinations of igneous olivine, augite, plagioclase, titaniferous magnetite, ilmenite, zeolites, gyrolite, sulfides, and chlorite-smectite intergrowths. Closer to the plutons, in the smectite zone, saponite and carbonate appear, primary olivine and gyrolite disappear, and zeolites decrease dramatically in abundance. Still closer to the plutons, in the amphibole zone, actinolite, edenite, chlorite, sphene, epidote, andradite, and quartz appear and saponite and chlorite-smectite intergrowths disappear. Along parts of the contact between gabbro and basalt, in the orthopyroxeneolivine zone, orthopyroxene, metamorphic olivine, and biotite appear and amphibole, chlorite, sphene, epidote, andradite, carbonate, and quartz disappear. Whole-rock chemical data indicate only minor change in the major-element chemical composition of the metabasalts during progressive metamorphism/hydrothermal alteration. Two-pyroxene eothermometry and various mineral-fluid equilibria suggest the range of peak temperatures attained in the metamorphic zones: orthopyroxene-olivine zone, 900°1, 030° C; amphibole zone, 400°–900° C; smectite and primary olivine zones, < 400° C. Mineralogical and oxygen isotopic alteration of the metabasalts were closely coupled: Basalts from the primary olivine zone with nearly unaltered igneous mineralogies have normal or near-normal wholerock ¹⁸O>+5 (SMOW); mineralogically more altered basalts from the smectite zone have whole-rock ¹⁸O=+2 to +5; still more mineralogically altered basalts from the amphibole zone (with one exception) have ¹⁸O<+ 2; completely recrystallized hornfelses from the orthopyroxene-olivine zone have ¹⁸O<0. The principal mechanism of isotope exchange between basalt and metamorphic/ hydrothermal fluid probably was heterogeneous mineralfluid reaction.Metabasalts from the orthopyroxene-olivine zone are mineralogically fresh pyroxene hornfelses that record crystallization temperatures > 1,000° C yet have highly altered whole-rock oxygen isotope compositions, ¹⁸O<0%. The hornfelses chemically interacted with metamorphic/hydrothermal fluids either at very high temperatures or while they were heated to > 1,000° C or both. Their mineralogy, however, rules out significant water-rock interaction after they cooled below 900° C. Hydrothermal convection on Skye was a two-stage process: (a) fluid flow through wall rocks initially was pervasive while they are heated; (b) fluid flow after the thermal peak in the wall rocks was sufficiently channelized that rocks such as those in the orthopyroxeneolivine zone were isolated from further fluid-rock interaction during all or almost all of the cooling history of the hydrothermal system.