The unified catalogue of earthquakes in central, northern, and northwestern Europe (CENEC)—updated and expanded to the last millennium

New databases motivate improvements and extensions of the catalogue by Grünthal and Wahlström (J Seismol 7:507–531, 2003a) – G&;W03 – of earthquakes in central, northern, and northwestern Europe with M _w?≥?3.50. Data from over 30 regional catalogues, the International Seismological Centre and U.S. National Earthquake Information Center bulletins for the NE Atlantic Ocean, and many special studies were analysed, largely along the lines of the previous study. Non-tectonic, non-seismic, and non-existing as well as duplicate events were identified and removed according to our current stage of knowledge. If not given by the original source, the moment magnitude, M _w, was calculated for each event with a specified epicentral location and a given strength measure (i.e., an original magnitude of any type or, for onshore events only, an intensity). The calculations follow transformation relations derived in the present or in our previous study. The investigated area is subdivided into 22 polygons, in each of which one or more local catalogues, supplemented by data from special studies, are used. If more than one catalogue lists an event, one entry was selected according to a priority algorithm specific for each polygon. If the selected catalogue entry contains more than one strength type, one was selected for the M _w calculation according to another priority scheme. The final catalogue, CENEC, is confined to the time period 1000–2004 and magnitudes M _w?≥?3.50. This is an extension of the time period covered by G&;W03 (1300–1993). The number of events has increased from about 5,000 to about 8,000. For each entry, available information on the date, time, location (including focal depth), intensity I ₀, magnitude M _w, and source (i.e., the local catalogue or special study) are given. The strength type and value from which M _w was calculated are also indicated. The catalogue is available on the website of the GFZ German Research Centre of Geosciences.     

Hydro-economic models: Concepts, design, applications, and future prospects

Future water management will shift from building new water supply systems to better operating existing ones. The variation of water values in time and space will increasingly motivate efforts to address water scarcity and reduce water conflicts. Hydro-economic models represent spatially distributed water resource systems, infrastructure, management options and economic values in an integrated manner. In these tools water allocations and management are either driven by the economic value of water or economically evaluated to provide policy insights and reveal opportunities for better management. A central concept is that water demands are not fixed requirements but rather functions where quantities of water use at different times have varying total and marginal economic values. This paper reviews techniques to characterize the economic value of water use and include such values in mathematical models. We identify the key steps in model design and diverse problems, formulations, levels of integration, spatial and temporal scales, and solution techniques addressed and used by over 80 hydro-economic modeling efforts dating back 45-years from 23 countries. We list current limitations of the approach, suggest directions for future work, and recommend ways to improve policy relevance.     

Assessment of marine benthic quality change in gradients of disturbance: Comparison of different Scandinavian multi-metric indices

Three multi-metric benthic macrofauna indices were used to assess marine benthic ecological quality status (EcoQS) according to the European Water Framework Directive, in seven pollution gradients mainly, western Scandinavia. The impacts included organic load, hypoxia, metals, urban effluents and physical disturbance. The indices responded in a similar threshold fashion, irrespective of impact factor identity. Usually, the border between Good and Moderate EcoQS (G/M), is determined as some deviation from a reference situation. References, however, are difficult to find. An alternative procedure is described to estimate the G/M border, not requiring reference data. Thresholds, where faunal structure deterioration commences, were identified from non-linear regressions between indices and impact factors. Index values from the less impacted side of the thresholds were assumed to come from environments of Good and High EcoQS, and the 5th percentile of these data, was defined as the G/M border. Estimated G/M borders compared well with previous studies.     

The effects of sulfidation and oxidation during metamorphism on compositionally varied rocks adjacent to the Bleikvassli Zn–Pb–(Cu) deposit, Nordland, Norway

Petrographic, electron microprobe, and bulk-rock geochemical analyses indicate that the distribution and composition of ferromagnesian silicates (biotite, garnet, and staurolite) in and adjacent to the metamorphosed Bleikvassli Zn–Pb–(Cu) volcanogenic massive sulfide deposit, Norway, are dependent upon the competing effects of f O₂–f S₂ and host-rock composition. The enrichment in magnesium content of these silicates within the orebody and at distances of as much as 5–10 m away is due to the increased f O₂ and f S₂ conditions imposed on the silicates in zones subject to minor hydrothermal alteration during regional metamorphism. Alternatively, within pelitic country rocks at distances >5–10 m from ore, the host-rock chemistry controls the composition of metamorphic silicate minerals. Also, country rocks within a few meters of ore are distinguished by the common presence of zinc-bearing staurolite (up to 9 wt% ZnO) coexisting with biotite ± garnet. Rocks in the Bleikvassli deposit were hydrothermally enriched in zinc and fluorine prior to metamorphism. The fluorine resides mainly in biotite, which is an additional contributing factor to the magnesium enrichment of that mineral due to Fe²⁺–F avoidance. Our inference that the sulfidation–oxidation halo around the Bleikvassli ore deposit is only meters in width contrasts with the view of Maiga (1983), who proposed the effects of sulfidation could be identified at distances >159 m from ore. It is evident that the delineation of a sulfidation–oxidation halo bordering a metamorphosed massive sulfide deposit must be done carefully in order to discriminate between the effects due to variations in primary rock composition versus those resulting from a sulfur and oxygen fugacity gradient between the massive sulfides and the sulfur-poor country rocks. Received: 1 March 1998 / Accepted: 3 May 2000     

Chemostratigraphy of upper Jurassic reservoir sandstones,Danish Central Graben,North Sea

A chemostratigraphic study of Upper Jurassic sandstones in the northern Danish Central Graben has been undertaken within the framework of a well-defined stratigraphic/sedimentological model based particularly on cored well sections. Two reservoir sandstone units are recognised, the transgressive marginal marine to shoreface sandstone of the Gert Member and the regressive to transgressive shoreface sandstone of the Ravn Member. Both members belong to the Heno Formation, which is equivalent to the Fulmar Formation (UK) and the Ula Formation (Norway).     

Siderophore adsorption to and dissolution of kaolinite at pH 3 to 7 and 22°C

Siderophores are Fe(III)-specific ligands produced by many aerobic microorganisms under conditions of iron stress. This study examined adsorption of the commercial trihydroxamate siderophore, desferrioxamine B (DFO-B), to an iron-containing kaolinite (0.1 bulk wt.% Fe) and examined DFO-B effects on initial kaolinite dissolution and iron release rates. Adsorption experiments were conducted at pH 3 to 8 in 0.01-M NaClO₄ in the dark and at 22°C; batch initial dissolution experiments were conducted to 96 h.The adsorption envelope (i.e., adsorption as a function of pH) of DFO-B on kaolinite was consistent with cation-like behavior, with adsorption increasing above kaolinite’s pH_pznpc of 4.9. DFO-B enhanced aluminum release from kaolinite at pH 3 to 7, relative to HNO₃, which is consistent with the ligand’s high binding affinity for Al. Correlation between DFO-B adsorption and aluminum release suggested a surface-controlled, ligand-promoted dissolution mechanism. DFO-B had no effect relative to HNO₃ on silicon release at pH 3 and 5, but moderately enhanced silicon release at pH 7. DFO-B enhanced iron release from kaolinite, with dissolved iron concentrations in the 10-ppb range at 96-h reaction time. These results show that kaolinite may serve as a source of iron to aerobic microorganisms in iron-limited conditions and that siderophores may affect kaolinite dissolution and iron content.     

Pre-orogenic upper crustal softening by lower greenschist facies metamorphic reactions in granites of the central Pyrenees

Pre-kinematic greenschist facies metamorphism is often observed in granites and basement units of mountain belts, but rarely dated and accounted for in orogenic cycle reconstructions. Studying pre-kinematic alteration is challenging because of its usual obliteration by subsequent syn-kinematic metamorphism often occurring at conditions typical of the brittle–ductile transition. It is, however, to be expected that pre-kinematic alteration has major implications for the rheology of the upper crust. In the 305 Ma-old Variscan basement of the Bielsa massif (located in the Axial Zone of the Pyrenees), successive fluid–rock interaction events are recorded in granites below 350°C. Combined microstructural and petrographic analysis, low-T thermobarometry and in situ U–Th/Pb dating of anatase, titanite and monazite show extensive pre-orogenic (pre-Alpine) and pre-kinematic alteration related to feldspar sericitization and chloritization of biotite and amphibole at temperatures of 270–350°C at 230–300 Ma. This event is followed by a second fluid–rock interaction stage marked by new crystallization of phyllosilicates at 200–280°C and is associated with the formation of mylonitic shear zones and fractures parallel to the shear planes. U–Pb anatase and monazite ages as well as the microtextural relationships of accessory minerals suggest an age for this event at 40–70 Ma, consistent with independent regional geology constraints. The Variscan basement was therefore softened at late to post-Variscan time, at least 150–200 Ma before the main Alpine shortening while Alpine-age compression (c. 35–50 Ma) leads to the formation of a dense net of mylonites. The associated deformation, both distributed at the scale of the Bielsa massif and localized at decametric scale in mylonitic corridors, precedes the strain localization along the major thrusts of the Axial Zone. The Bielsa massif is a good example where inherited, pre-orogenic upper crustal softening controls the deformation patterns in granitic basement units through low-grade metamorphic reactions.     

On measuring the gravitational-wave background using Pulsar Timing Arrays

The long-term precise timing of Galactic millisecond pulsars holds great promise for measuring the long-period (months to years) astrophysical gravitational waves. Several gravitational-wave observational programs, called Pulsar Timing Arrays (PTA), are being pursued around the world.
Here, we develop a Bayesian algorithm for measuring the stochastic gravitational-wave background (GWB) from the PTA data. Our algorithm has several strengths: (i) it analyses the data without any loss of information; (ii) it trivially removes systematic errors of known functional form, including quadratic pulsar spin-down, annual modulations and jumps due to a change of equipment; (iii) it measures simultaneously both the amplitude and the slope of the GWB spectrum and (iv) it can deal with unevenly sampled data and coloured pulsar noise spectra. We sample the likelihood function using Markov Chain Monte Carlo simulations. We extensively test our approach on mock PTA data sets and find that the algorithm has significant benefits over currently proposed counterparts. We show the importance of characterizing all red noise components in pulsar timing noise by demonstrating that the presence of a red component would significantly hinder the detection of the GWB.
Lastly, we explore the dependence of the signal-to-noise ratio on the duration of the experiment, number of monitored pulsars and the magnitude of the pulsar timing noise. These parameter studies will help formulate observing strategies for the PTA experiments.