A review of the premium-protection method and its possible application in detection of displacements

A statistical technique using the concepts of Premium-Protection for error detection is applied to deformation measurement. The most attractive aspect of the method is the expression of test values involved in terms of size of deformation (within the limits of a particular design) to be detected. As a demonstration observations from a dam settlement survey are analysed.     

Evolution of permafrost in China during the last 20 ka

The formation and evolution of permafrost in China during the last 20 ka were reconstructed on the basis of large amount of paleo-permafrost remains and paleo-periglacial evidence, as well as paleo-glacial landforms, paleo-flora and paleofauna records. The results indicate that, during the local Last Glacial Maximum(LLGM) or local Last Permafrost Maximum(LLPMax), the extent of permafrost of China reached 5.3×106-5.4×106 km2, or thrice that of today, but permafrost shrank to only0.80×106-0.85×106 km2, or 50% that of present, during the local Holocene Megathermal Period(LHMP), or the local Last Permafrost Minimum(LLPMin). On the basis of the dating of periglacial remains and their distributive features, the extent of permafrost in China was delineated for the two periods of LLGM(LLPMax) and LHMP(LLPMin), and the evolution of permafrost in China was divided into seven periods as follows:(1) LLGM in Late Pleistocene(ca. 20000 to 13000-10800 a BP)with extensive evidence for the presence of intensive ice-wedge expansion for outlining its LLPMax extent;(2) A period of dramatically changing climate during the early Holocene(10800 to 8500-7000 a BP) when permafrost remained relatively stable but with a general trend of shrinking areal extent;(3) The LHMP in the Mid-Holocene(8500-7000 to 4000-3000 a BP)when permafrost degraded intensively and extensively, and shrank to the LLPMin;(4) Neoglaciation during the late Holocene(4000-3000 to 1000 a BP, when permafrost again expanded;(5) Medieval Warming Period(MWP) in the late Holocene(1000-500 a BP) when permafrost was in a relative decline;(6) Little Ice Age(LIA) in the late Holocene(500-100 a BP), when permafrost relatively expanded, and;(7) Recent warming(during the 20 th century), when permafrost continuously degraded and still is degrading. The paleo-climate, geography and paleopermafrost extents and other features were reconstructed for each of these seven periods.     

Detecting Changes in Ground Water Quality at Regulated Facilities

The Resource Conservation and Recovery Act (PL 94–580) and related federal and state legislation have mandated routine monitoring of ground water quality at regulated facilities. The objective of the required monitoring activities is detection of adverse changes in ground water quality caused by the facilities.
Both failure to detect pollution and an incorrect determination of pollution can be very expensive. It is crucial, therefore, that monitoring programs be designed and operated to provide statistically sound information. It is equally important that users of ground water quality data understand the nature and limitations of information from monitoring.
To address the preceding issues, the authors present a general approach to analyzing ground water quality data in light of the stated monitoring objective. The suggested approach accounts for "natural" variation in background water quality through pairing of observations. The limitations of quarterly sampling for detecting small changes in quality over a short time frame are discussed.     

Volumetric characteristics of lava flows from interferometric radar and multispectral satellite data: the 1995 Fernandina and 1998 Cerro Azul eruptions in the western Galápagos

We have used a suite of remotely sensed data, numerical lava flow modeling, and field observations to determine quantitative characteristics of the 1995 Fernandina and 1998 Cerro Azul eruptions in the western Galápagos Islands. Flank lava flow areas, volumes, instantaneous effusion rates, and average effusion rates were all determined for these two eruptions, for which only limited syn-eruptive field observations are available. Using data from SPOT, TOPSAR, ERS-1, and ERS-2, we determined that the 1995 Fernandina flow covers a subaerial area of 6.5×10⁶ m² and has a subaerial dense rock equivalent (DRE) volume of 42×10⁶ m³. Field observations, ATSR satellite data, and the FLOWGO numerical model allow us to determine that the effusion rate declined exponentially from a high of ~60–200 m³ s^-1 during the first few hours to <5 m³ s^-1 prior to ceasing after 73 days, with a mean effusion rate of 4–16 m³ s^-1. Integrating the ATSR-derived, exponentially declining effusion rate over the eruption duration produces a total (subaerial + submarine) DRE volume of between 27 and 100×10⁶ m³, the range in values being due to differing assumptions about heat loss characteristics; only values in the higher part of this range are consistent with the independently derived subaerial volume. Using SPOT, TOPSAR, ERS-1, and ERS-2 data, we determine that the 1998 Cerro Azul flow is 16 km long, covers 16 km², and has a DRE volume of 54×10⁶ m³. FLOWGO produces at-vent velocity and effusion rate values of 11 m s^-1 and ~600 m³ s^-1, respectively. The velocity value agrees well with the 12 m s^-1 estimated in the field. The mean effusion rate (total DRE volume/duration) was 7–47 m³ s^-1. Dike dimensions, fissure lengths, and pressure gradients along the conduit based on magma chamber depth estimates of 3–5 km produce mean effusion rates for the two eruptions that range over nearly four orders of magnitude, the range being due to uncertainty in the magma viscosity, dike dimensions, and pressure gradient between magma chamber and vent. Although somewhat consistent with mean effusion rates from other techniques, their wide range makes them less useful. The exponentially declining effusion rates during both eruptions are consistent with release of elastic strain being the driving mechanism of the eruptions. Our results provide independent input parameters for previously published theoretical relationships between magma chamber pressurization and eruption rates that constrain chamber volumes and increases in volume prior to eruption, as well as time constants of exponential decay during the eruption. The results and theoretical relationships combine to indicate that at both volcanoes probably 25–30% of the volumetric increase in the magma chamber erupted as lava onto the surface. In both eruptions the lava flow volumes are less than 1% of the magma chamber volume.     

Vertical distribution of plankton in the skagerrak in relation to doming of the seasonal thermocline

In the central Skagerrak between Norway and Denmark, the seasonal thermocline tends to be relatively shallow (10 to 15 m) probably due to geostrophic effects. An investigation of phytoplankton distribution in this region in late August 1981 showed the presence of an intense subsurface chlorophyll maximum (up to 30 γ 1⁻ Chl a) at a temperature of <6°C, dominated by coccolithophores and the dinoflagellate, Prorocentrum minimum. Data are presented on the vertical distribution of zooplankton in relation to these phytoplankton populations.     

Environmental management in Antarctica Instruments and institutions

Instruments and institutions for environmental management in Antarctica have evolved from beginnings in the Antarctic Treaty, with subsequent introduction of the Convention for the Conservation of Antarctic Seals, the Convention on the Conservation of Antarctic Marine Living Resources, and recommendations made at Treaty meetings. The Protocol on Environmental Protection to the Antarctic Treaty will improve existing provisions for environmental management in Antarctica. When it enters into force the Protocol will apply to all activities in the Treaty area: it provides rules for environmental impact assessment, conservation of fauna and flora, disposal of wastes, prevention of marine pollution and specially protected and managed areas. The Protocol's Committee for Environmental Protection will facilitate discussion and advice on environmental management. Management of information is a vital part of ensuring measures are effective. The Protocol should be ratified quickly to improve the basis for environmental protection, but the test will be whether and how it is implemented in practice.     

Shaking table tests of a resilient bridge system with precast reinforced concrete columns equipped with springs

This paper presents the shake table test results of a novel system for the design of precast reinforced concrete bridges. The specimen comprises a slab and four precast columns. The connections are dry and the columns are connected to the slab by an ungrouted tendon. One of the tendon ends is anchored above the slab, in series with a stack of washer springs, while the other end is anchored at the bottom of the column. The addition of such a flexible restraining system increases the stability of the system, while keeping it relatively flexible allowing it to experience negative post-uplift stiffness. It is a form of seismic isolation. Anchoring the tendon within the column, caps the design moment of the foundation, and reduces its size. One hundred and eighty-one shake table tests were performed. The first 180 caused negligible damage to the specimen, mainly abrasion at the perimeter of the column top ends. Hence, the system proved resilient. The 181^st excitation caused collapse, because the tendons unexpectedly failed at a load less than 50% of their capacity (provided by the manufacturer), due to the failure of their end socket. This highlights the importance of properly designing the tendons. The tests were used to statistically validate a rigid body model. The model performed reasonably well never underestimating the median displacement response of the center of mass of the slab by more than 30%. However, the model cannot predict the torsion rotation of the slab that was observed in the tests and is due to imperfections.     

Petrogenesis of orthopyroxene- and amphibole-bearing andesites, Mustique, Grenadine Islands, Lesser Antilles Arc: Isotope, trace element and physical constraints

Abstract On the island of Mustique, fresh and propylitized olivine–plagioclase–clinopyroxene basalt, plagioclase–clinopyroxene–orthopyroxene and plagioclase–clinopyroxene–amphibole andesite lavas and minor intrusions are interbedded with Oligocene pyroclastic and epiclastic rocks. Chemical data show that two isotopically identical, but chemically different, suites of lava are present: (i) the OPXS (⁸⁷Sr/⁸⁶Sr 0.70403–0.70454; ¹⁴³Nd/¹⁴⁴Nd 0.512952–0.512986; δ¹⁸O_cpx 5.49 and 5.61), comprising basalts and orthopyroxene‐bearing andesites; and (ii) the AMPHS (⁸⁷Sr/⁸⁶Sr 0.70401–0.70457; ¹⁴³Nd/¹⁴⁴Nd 0.512981–0.513037; δ¹⁸O_cpx 5.54), made up of basalts and amphibole‐bearing andesites. The OPXS has higher contents of TiO₂, P₂O₅, light rare earth elements, Sm, Pb, Th, U, Zr, Y and Nb, and higher La/Yb ratios than the AMPHS. The isotopic data suggest that both suites formed from melts derived from the same subduction‐modified depleted mantle source as the volcanic rocks of nearby St Vincent and Bequia, and the northern islands of the Lesser Antilles Arc. The immobile trace element contents, and La/Yb ratios, of the OPXS are indicative of ～10% partial melting of the source, whereas those of the AMPHS are indicative of ～25% partial melting. The within‐suite chemical variation of the OPXS is consistent with ～45% fractional crystallization of its intratelluric mineral assemblages, and that of the AMPHS is consistent with the removal of ～65% of its intratelluric assemblages. Experimental evidence suggests that both suites of basalt crystallized at pressures <8 kbar from melts containing 1–2 wt% water. After extensive fractional crystallization, the andesites crystallized at pressures between approximately 5 and 2 kbar. The OPXS magmas appear to have lost more of their water content than the AMPHS magmas. Thus, the OPXS andesites formed from melts with an estimated water content of 2–3 wt%, whereas the AMPHS andesites formed from melts containing at least 4.5 wt% water.