When the earth blisters: Exploring recurrent liquefaction features in the coastal system of Christchurch,New Zealand

The 14 February, or Valentine's Day, 2016 earthquake located offshore of Christchurch produced a new generation of liquefaction in the coastal environment of Christchurch, an environment of recurrent liquefaction during the 2010–2011 Canterbury Earthquake Sequence. The Valentine's Day earthquake occurred while trenches were open at a site in the coastal environment for studying the 2010–2011 liquefaction features. Observations in the 2016 trenches provided insights into the formation of a suite of surface and subsurface liquefaction features characteristic of the dune deposits, related to the persistent shallow water table, well‐sorted sands within the liquefiable layer and the soil above. Given these conducive conditions, there is a high potential that all earthquakes capable of inducing liquefaction may have been recorded during formation of the dunes near Christchurch. However, overprinting by subsequent generations of liquefaction features may be common and present challenges in unravelling the event history.     

The first climate refugees? Contesting global narratives of climate change in Tuvalu

Climate change effects such as sea-level rise are almost certain. What these outcomes mean for different populations, however, is far less certain. Climate change is both a narrative and material phenomenon. In so being, understanding climate change requires broad conceptualisations that incorporate multiple voices and recognise the agency of vulnerable populations. In climate change discourse, climate mobility is often characterised as the production of ‘refugees’, with a tendency to discount long histories of ordinary mobility among affected populations. The case of Tuvalu in the Pacific juxtaposes migration as everyday practice with climate refugee narratives. This climate-exposed population is being problematically positioned to speak for an entire planet under threat. Tuvaluans are being used as the immediate evidence of displacement that the climate change crisis narrative seems to require. Those identified as imminent climate refugees are being held up like ventriloquists to present a particular (western) ‘crisis of nature’. Yet Tuvaluan conceptions of climate challenges and mobility practices show that more inclusive sets of concepts and tools are needed to equitably and effectively approach and characterise population mobility.     

Comment on "Two New Carbonate Stable Isotope Standards"

Friedman et al (1) propose that NBS 19 calcium carbonate substitute for PDB. This is in apparent conflict with the recommendation of the September 1976 consultants' meeting convened by the International Atomic Energy Agency on stable isotope standards. Furthermore, Friedman et al suggest ɛ-values be adopted for NBS 19 that do not take into account the ɛ-values of NBS 20 (Solenhofen limestone). We believe that adoption of these proposals may lead to confusion in the stable isotope literature and to lack of correspondence between historic and future isotopic results.
In sharp contrast to the results of Friedman et al (1), we find NBS 20 to be a satisfactory reference material if it is handled properly.     

VLBI Imaging of Luminous Infrared Galaxies: Starbursts & AGN

As described by Colin Lonsdale in this Workshop, VLBI observations reveal thepresence of both AGN and Starburst activity in Luminous Infrared Galaxies.We highlight new results on two classical LIGs which span the range of LIGradio activity: Arp 220, which reveals luminous radio supernovae (RSN)produced in an intense starburst, and Mrk231, which has a powerful compact,AGN radio core. Second epoch observations of the compact radio sources inArp 220 confirm their nature as luminous Radio Supernovae, but indicate alower luminous RSN frequency (_LRSN 0.3 yr^-1) andconsequent slower decay rate than previously suggested. We interpret thisas due to the dense starburst medium into which the supernovaedetonate. The compact radio morphology of Mrk231 places it among theCompact Symmetric Objects (CSOs) which are suggested to be young radio sources in which asymmetric lobes or hotspots reveal theworking surface of a relativistic jet upon the ambient medium. Assumingthat the lobes in Mrk 231 are confined by ram pressure, we estimate an agefor the jet/compact source, 10⁶yr. We interpret Mrk 231as a newly formed QSO emerging from a starburst.     

Eutrophication and some European waters of restricted exchange

Regions of Restricted Exchange (RREs) are an important feature of the European coastline. They are historically preferred sites for human settlement and aquaculture and their ecosystems, and consequent human use, may be at risk from eutrophication. The OAERRE project (EVK3-CT1999-0002) concerns ‘Oceanographic Applications to Eutrophication in Regions of Restricted Exchange’. It began in July 2000, and studies six sites. Four of these sites are fjords: Kongsfjorden (west coast of Spitzbergen); Gullmaren (Skagerrak coast of Sweden); Himmerfjärden (Baltic coast of Sweden); and the Firth of Clyde (west coast of Scotland). Two are bays sheltered by sand bars: Golfe de Fos (French Mediterranean); and Ria Formosa (Portuguese Algarve). Together they exemplify a range of hydrographic and enrichment conditions. The project aims to understand the physical, biogeochemical and biological processes, and their interactions, that determine the trophic status of these coastal marine RRE through the development of simple screening models to define, predict and assess eutrophication. This paper introduces the sites and describes the component parts of a basic screening model and its application to each site using historical data. The model forms the starting point for the OAERRE project and views an RRE as a well-mixed box, exchanging with the sea at a daily rate E determined by physical processes, and converting nutrient to phytoplankton chlorophyll at a fixed yield q. It thus uses nutrient levels to estimate maximum biomass; these preliminary results are discussed in relation to objective criteria used to assess trophic status. The influence of factors such as grazing and vertical mixing on key parameters in the screening model are further studied using simulations of a complex ‘research’ model for the Firth of Clyde. The future development of screening models in general and within OAERRE in particular is discussed. In addition, the paper looks ahead with a broad discussion of progress in the scientific understanding of eutrophication and the legal and socio-economic issues that need to be taken into account in managing the trophic status of RREs.     

Fluid and Solute Transport from a Conduit to the Matrix in a Carbonate Aquifer System

Within carbonate systems, the working hypothesis suggests that when a conduit is flooded fluid and solute migrate from the conduit into the matrix. This flux of fluid and solute into the matrix creates a reservoir that can be slowly released once the flooding recedes. Although hypothesized, these fluxes have never been measured. To quantify the distance that a fluid and solute would move into a matrix, the fluxes of fluid and solute from a conduit into a matrix were simulated for nine different carbonate aquifer systems. Two independent numerical approaches were used to simulate (1) fluid flux into the matrix and (2) solute flux into the matrix during a flooding event. When flooding occurs within the conduit, the volume of water transported into and stored in the matrix with a high porosity and high hydraulic conductivity (Floridan Aquifer) was less than 0.34 m³ along a 1 m length of conduit, resulting in a penetration depth of 7.2×10⁻² m into the matrix. In a low porosity and low hydraulic conductivity matrix (Ozark Plateau), the volume of water transported into and stored in the matrix was less than 6.85×10⁻⁵ m³ along a 1 m length of conduit, resulting in a penetration depth of 2.0×10⁻⁴ m into the matrix. Simulated solute flow shows that less than 0.1% of the solute moves in to the matrix. The two approaches demonstrate that during high flow conditions fluid and solute are forced through the conduits, with very little moving into the carbonate matrix. Once the fluid and solute enter a conduit and are moving, they will remain in the conduit until they are discharged at an outlet. Thus, a carbonate matrix does not become a reservoir for solute and fluid during a high-flow event.     

Integrated economic and environmental satellite accounts

This Forum article and the Forum article that follows are reprinted from articles that appeared in theSurvey of Current Business in the April 1994 issue with permission of the U.S. Department of Commerce, Bureau of Economic Analysis BE-64, Washington, D.C. 20230. These articles are being reprinted in the interest of readers ofNonrenewable Resources. The only changes from the original articles are those that were necessary to conform with the guidelines for Forum articles in the journal; these changes included the deletion of technical and qualifying information that was provided in foot-notes in the original articles. Bibliographic references are given at the end of the second Forum article.