bluuebunny/crossref_metadata_2025 huggingface dataset:
Power-law extreme flood frequency
Authors: Kidson R. , Richards K. S. , Carling P. A.
Published: April 2008

Conventional Flood Frequency Analysis (FFA) has been criticized both for its questionable theoretical basis, and for its failure in extreme event prediction. An important research issue for FFA is the exploration of models that have theoretical/explanatory value as the first step towards more accurate predictive attempts. Self-similar approaches offer one such alternative, with a plausible theoretical basis in complexity theory that has demonstrable wide applicability across the geophysical sciences. This paper explores a simple self-similar approach to the prediction of extreme floods. Fifty river gauging records from the USA exhibiting an outlier event were studied. Fitting a simple power law (PL) relation to events with return period of 10 years or greater resulted in more accurate discharge and return period estimates for outlier events relative to the Log-Pearson III model. Similar success in predicting record events is reported for 12 long-term rainfall records from the UK. This empirical success is interpreted as evidence that self-similarity may well represent the underlying physical processes generating hydrological variables. These findings have important consequences for the prediction of extreme flood events; the PL model produces return period estimates that are far more conservative than conventional distributions.
Models, data and mechanisms: quantifying wildfire regimes
Authors: Millington James D. A. , Perry George L. W. , Malamud Bruce D.
Published: April 2008

The quantification of wildfire regimes, especially the relationship between the frequency with which events occur and their size, is of particular interest to both ecologists and wildfire managers. Recent studies in cellular automata (CA) and the fractal nature of the frequency-area relationship they produce has led some authors to ask whether the power-law frequency-area statistics seen in the CA might also be present in empirical wildfire data. Here, we outline the history of the debate regarding the statistical wildfire frequency-area models suggested by the CA and their confrontation with empirical data. In particular, the extent to which the utility of these approaches is dependent on being placed in the context of self-organized criticality (SOC) is examined. We also consider some of the other heavy-tailed statistical distributions used to describe these data. Taking a broadly ecological perspective we suggest that this debate needs to take more interest in the mechanisms underlying the observed power-law (or other) statistics. From this perspective, future studies utilizing the techniques associated with CA and statistical physics will be better able to contribute to the understanding of ecological processes and systems.
‘Transgressive washing’ concept: a sequence stratigraphic approach for calci- and siliciclastic turbidites
Authors: El Kadiri Kh. , Chalouan A. , Bahmad A. , Salhi F. , Liemlahi H.
Published: April 2008

Carbonate breccias, calciturbidites and sandstone flysch sediments are typically assigned to the lowstand regime, based on the double assumption that these thick sedimentary packages necessitate (1) emergence phases for the production of their terrigenous material, and (2) a relatively lower position of the shoreline, which did not lie too far from the shelf-break line. In strictly regarding these conditions, we can run the risk of neglecting the role played by the transgression-related currents in reworking and exporting basinward bioclastic and siliciclastic sands from shelves. The ‘transgressive washing’ concept proposed here accounts for the latter mechanism, particularly in the case when the stratigraphic record shows that the onset of both the calci- and siliciclastic material was contemporaneous with newly marine-encroached continental source areas. Four examples from the Rifian internal (source) and external zones (basin) are presented to illustrate this phenomenon.
Mauretanian flysch nappe in the northwestern Rif Cordillera (Morocco): deformation chronology and evidence for a complex nappe emplacement
Authors: Chalouan A. , El Mrihi A. , El Kadiri Kh. , Bahmad A. , Salhi F. , Hlila R.
Published: April 2008

This study deals with the Mauretanian flysch nappe in the southern side of the Gibraltar Strait, NW of the Rif belt (Morocco), where it is possible to better appraise the stacking pattern of its two structural components (the Tisirene and Béni Ider nappes), and to decipher the chronology of deformation and its structural relationships with the overlying (Predorsalian and Numidian nappes) and the underlying nappes (Melloussa and Intrarif units). It is found that the main deformations were produced by an intermittent compressional regime, during which north-south- to NW-SE-directed compressional phases alternated with ENE-WSW to east-west-directed compressional ones. Whereas the former were generated by the Africa-Iberia convergence and resulted in small-scale thrusts and a brittle deformation style, the latter were driven by the west-drifting Alboran plate and resulted in paroxysmal fold-thrust deformations. Field evidence shows that the emplacement of the Mauretanian nappe over the Massylian one and the Intrarif units operated by inter-related compressional and gravitational processes, by virtue of which the majority of nappes stacked in an out-of-sequence regime. The precise age of the paroxysmal phases remains uncertain because of paucity or absence of direct stratigraphical data. However, this structural evolution is likely to have started as early as the mid-Burdigalian, when sedimentation synchronously ceased in the flysch trough. Its final phases may be placed precisely between the Langhian (N8) age of the most recent formations overlapped by these nappes and the late Tortonian age of the oldest formations transgressively covering them.
Tectonosedimentary evolution of the Plio-Pleistocene Sant’Arcangelo Basin (Southern Apennines, Italy)
Authors: Benvenuti M. , Bonini M. , Moratti G. , Sani F.
Published: April 2008

This paper describes a new tectonosedimentary model for the evolution of the Plio-Quaternary Sant’Arcangelo Basin, located in the Southern Apennines of Italy. To this purpose, we carried out a new field survey of the basin fill, closely integrating stratigraphy, facies analysis, and structural and tectonic analyses. The geological map at 1:50 000 scale of the whole basin is the first result of this work. We present a new stratigraphic framework for the Sant’Arcangelo Basin succession, which has been subdivided into five major stratigraphic groups, classified as synthems, following the recognition of major basin-wide unconformities. The synthems include smaller-scale stratigraphic units, which are classified as depositional sequences or sub-synthems. These sub-units are composed of different lithofacies assemblages recording cyclic activation of fluvial, deltaic, shallow marine and lacustrine environments throughout the evolution of the basin. Integration of facies analysis and tectonic data led to the definition of a series of palaeogeographical sketches, encompassing the Piacenzian and late Pleistocene, which mark the main steps in the evolution of the Sant’Arcangelo Basin. Basin-scale hinterland-verging thrust faults and folds controlled the development of sub-basins and the progressive isolation of the Sant’Arcangelo Basin from the Ionian foredeep. The new model presented here defines the Sant’Arcangelo Basin as a triangular-shaped basin, bounded by oppositely verging thrusts. The hinterland-verging Valsinni thrust anticline limited its eastern margin and exerted a major control on the basin evolution.
Crustal magnetism of the Southern Tyrrhenian Sea from aeromagnetic surveys
Authors: Piangiamore G. L. , Faggioni O. , Barbano M. S.
Published: April 2008

Aeromagnetic data from the Southern Tyrrhenian Sea have been analysed, to remove the contributions of shallow and deep sources to the magnetic anomalies by applying a processing technology that increases the informative potential of the magnetic data acquired by AGIP with great accuracy, uniform distribution and high density. The aeromagnetic anomaly field has been reduced to the bottom topographic surface by the bottom reduction method. Spectral signal analysis has been carried out to separate low- and high-frequency components. The spectral reference field (SRF), obtained from the cotransformation of low frequencies, gives information about deep magnetic structures. The high-frequency components, computed from the difference between the magnetic anomaly field and the SRF, provides the spectral anomaly field (SAF). The bottom reduced magnetic anomaly field is derived by merging the high- and low-frequency bands. The resulting map provides information about geotectonic features in the Southern Tyrrhenian area and shows the effectiveness of the adopted approach over traditional procedures.
Hinterland geology and continental margin growth: the case of the Gioia Basin (southeastern Tyrrhenian Sea)
Authors: Gamberi F. , Marani M.
Published: April 2008

The Gioia Basin is a small trough located in the southeastern Tyrrhenian Sea between the Aeolian island arc and Sicily and Calabria. It is experiencing a post-rift margin evolution, while tectonic deformation and high rates of vertical movement are still affecting the Sicilian and Calabrian mainland. The analysis of the evolution of the post-rift depositional systems along the various sectors of the Gioia Basin margin has been carried out through the combined interpretation of multibeam bathymetry and seismic reflection data. Two seismic units have been identified and their component geomorphological elements ascertained through the analysis of seismic facies distribution. In general, the depositional architecture of the margin, the sedimentary environments and facies and related geomorphological elements that are active in the shaping of the margin appear to be mainly controlled by the physiography of the basin itself and by the geology of the hinterland that results from the structural evolution of the adjacent land areas. An evolution from a generalized slope bypass setting to a prograding offlapping slope architecture is recognized and explained as due to the transition from an out-of-grade to a graded profile progressing from the early post-rift stage to the later margin growth stage. Along the Sicilian margin, a constructional apron, mainly consisting of channel levee deposits, makes up much of the studied sedimentary package and reflects a high sediment supply related to the large size of river catchments on land. In contrast, the northeastern Sicilian basin sector is a destructional margin that flanks a region where small river drainage systems result in a low sediment supply to the basin and a continued high uplift rate promotes slope instability; as a consequence, the basin infill is here almost completely made up of mass-wasting deposits. In the Calabrian margin, a first phase of low sediment supply probably coinciding with the filling of the further inland Gioia Tauro half-graben was followed by the establishment of the Gioia-Mesima channel-canyon system that, furnishing an effective sediment flux to the margin, allows the formation of an intraslope depositional body consisting of channelized turbidite lobes.
Sedimentary and diagenetic environments of the Wildmoor Sandstone Formation (UK): implications for groundwater and contaminant transport, and sand production
Authors: Bouch Jon E. , Hough Ed , Kemp Simon J. , McKervey John A. , Williams Geoffrey M. , Greswell Richard B.
Published: April 2008

The Wildmoor Sandstone Formation, proved in three boreholes drilled at Birmingham University, is dominated by fine- to medium-grained sandstones deposited in a braided river environment, within which channel lag, channel fill and abandoned channel facies are recognized. Minor proportions of aeolian sandsheet are present, as are dolocretes, not previously reported in the formation.

The sandstones are feldspathic and lithic arenites, and typically are clay-poor. Early dolomite dominates the diagenetic overprint, and is preferentially developed in channellag deposits. Burial diagenetic effects are minor. Late calcite occurs as a pore-filling phase and within fractures.

Minor fractures and granulation seams are oriented parallel to the NE-SW Birmingham Fault. ‘Conventional’ granulation seams, with comminution of detrital material, and more complex seams containing comminuted dolomite cement with a millimetre-wide halo of dolomite cement are present, the latter implying that the sandstone was dolomitecemented at the time of fracturing.

Several scales of heterogeneity will affect groundwater solute transport. The palaeosols and abandoned channel mudstones may act as barriers to vertical flow at the decimetre scale. Dolomite-cemented channel-lag deposits may act similarly at smaller scales. Granulation seams have permeabilities of two-three orders of magnitude lower than their host sandstones, but their limited occurrence may limit their impact on larger scale flow. Matrix permeability is controlled by grain size and dolomite cement.

The fines in the fine-grained, ripple cross-laminatied sandstones were extensively washed out during coring, and this lithology may be a source of sand yields in some sandstone boreholes. Although no enhancement of particle yields was seen during packer testing, the possibility remains that more comprehensive failure may occur at higher pumping rates.
Non-reactive solute movement through saturated laboratory samples of undisturbed stratified sandstone
Authors: Bashar Khairul , Tellam John H.
Published: April 2008

There has been much recent work on developing models of non-reactive solute migration in saturated stratified porous media. Almost all experimental results against which the models have been tested have been obtained using artificial media. The aim of the present study is to test the models against data from naturally stratified media. In this paper we report the results of the experiments carried out on samples of laminated, intact, saturated Triassic sandstone from the UK. Column experiments were performed at steady flow rates using samples with flow either parallel or perpendicular to the lamination. For flow parallel to the lamination, the breakthrough curves were asymmetrical. They were generally characterized by early breakthrough and tailing. Asymmetry and tailing increased with increasing flow rate. Column experiments in which flow was interrupted showed the presence of physical non-equilibrium. For flow perpendicular to the lamination the breakthrough curves were symmetrical. Simultaneous use of bromide and amino-G-acid, conservative tracers having very different diffusion coefficients, demonstrated the significance of diffusion particularly when the flow is parallel to the lamination. Thinsection analysis, dye staining and positron emission projection imaging (PEPI) techniques were used to study the spatial variations in hydraulic properties in the samples. Thinsection analysis indicated that the thickness of individual layers, each of different porosity and grain size, varies from less than 1 mm to several millimetres and occasionally exceeds 1 cm. The dye and PEPI experiments also identified stratification of flow when the flow is parallel to the lamination, but in the latter case the most obvious stratification was at a larger scale than for the former. No preferential flow was found for samples with flow perpendicular to the lamination. It is concluded that the dominant process in solute migration in the sandstone samples is stratification that is, at least, at two scales, a process which will result in a fractionation where two solutes of different diffusion coefficient are present.
Compositional changes in a fumarolic field, Vulcano Island, Italy: a statistical case study
Authors: Buccianti A. , Tassi F. , Vaselli O.
Published: April 2008

The identification of compositional changes in fumarolic gases of active volcanic areas is one of the most important objectives in monitoring programmes. Together with information from seismic data and deformation, it provides key data to the formulation and management of emergency plans for populations living near active volcanoes.

Chemical data obtained from different fumaroles collected at Vulcano Island (Sicily, southern Italy) between 2000 and 2004 have been analysed statistically. The methodology has identified parameters able to elucidate the structure of the complex fumarolic field of Vulcano in the investigated span of time, notwithstanding the high data variability. The southern portion of the Tyrrhenian Sea was affected by an earthquake (
M
= 5.8, 40 km NE of Palermo) in December 2002. Abrupt outgassing on the island of Panarea occurred in November 2002 and Stromboli was significantly active from December 2002 to July 2003. The great geological instability of the area is thought to have had an influence on the variability shown by the data.

The time-dependent variations in the components of the data have been investigated using logratios. The H
2
O-HCl-SO
2
subcomposition, for a limited set of fumaroles, has been used to check for log-contrast principal components to be considered as a monitoring tool of volcanic activity. Results obtained indicate that the compositional changes are a complex function of time, chemistry, temperature and space. ANOVA (analysis of variance) of log-ratios for which there is no time dependence has elucidated components subject to significant spatial variations across the fumarole field, due to changes in redox conditions, and components dominated by random variations.
Exploratory compositional data analysis
Authors: Daunis-I-Estadella J. , Barceló-Vidal C. , Buccianti A.
Published: April 2008

This paper presents the first steps that should be performed whenever the study of a compositional dataset is initiated. Centre, variation matrix and total variance of a compositional dataset are introduced. In addition the biplots are also introduced as a powerful tool to analyse and discover special features related to subcompositions. The exploratory methodology is applied to a dataset consisting of the major, minor and trace elements composition of soil samples from several places in Tuscany (Italy). The structure of the data, collected from three different known country rocks of ophiolitic nature (basic and ultrabasic rocks), represent an interesting case study for experimenting on new methodologies of statistical investigation and for pointing out differences related to parental chemistry and mineralogy as well as the nature of processes to be related to the subsequent evolution.
Rounded zeros: some practical aspects for compositional data
Authors: Martín-Fernández J. A. , Thió-Henestrosa S.
Published: April 2008

It is very important to realize that the well-known ‘zeros problem’ in compositional data is inherent in the nature of the data rather than in the log-ratio methodology. In a strict sense, any null value is informative itself and needs specific treatment before a multivariate method is applied. In the
rounded zero
case specific techniques of missing data should be applied as a previous step, taking into account that any of these techniques must respect the compositional nature of the data. In practice, when an imputation method is applied, then it is necessary to make a sensitivity analysis of the results from multivariate analysis. These methodological aspects are applied and illustrated using compositional data from geological samples.
Permo-Carboniferous climate: Early Pennsylvanian to Late Permian climate development of central Europe in a regional and global context
Authors: Roscher Marco , Schneider Joerg W.
Published: April 2008

A well-justified stratigraphical correlation of continental successions and new palaeogeographic reconstruction of Pangaea reveal new insights into the northern Pangaean climate development influenced by palaeogeography, palaeotopography, glacio-eustatic sealevel changes and ocean currents. The overall Permo-Carboniferous aridization trend was interrupted by five wet phases. These are linked to the Gondwana icecap. The aridization and weakening of wet phases over time were not only caused by the drift of northern Pangaea to the arid climatic belt, but also by the successive closure of the Rheic Ocean, which caused the expansion of arid/semi-arid environments in the Lower/Middle Permian. The end of the Gondwana glaciation rearranged ocean circulation, leading to a cold, coast-parallel ocean current west of northern Pangaea, blocking moisture coming with westerly winds. The maximum of aridity was reached during the Roadian/Wordian. The Trans-Pangaean Mountain Belt was non-existent. Its single diachronous parts never exceeded an average elevation of 2000 m. The maximum elevation shifted during time from east to west. The Hercynian orogen never acted as an orographic east-west barrier, and the Inter-Tropical Convergence Zone was widely displaced, causing four seasons (dry summer/winter, wet spring/autumn) at the equator and a strong monsoon system.
Quantitative magnetic resonance imaging methods for core analysis
Authors: Chen Quan , Rack Frank R. , Balcom Bruce J.
Published: April 2008

The majority of sedimentary rocks have significant paramagnetic impurities, which lead to magnetic resonance signal lifetimes too short to be detected by clinical magnetic resonance imaging (MRI) methods. Quantitative information is the ultimate goal for rock-core analysis. The SPRITE (single-point ramped imaging with
T
1
enhancement) imaging technique has proven to be a very robust and flexible method for the study of a wide range of systems with short signal lifetimes. As a pure phase-encoding technique, SPRITE is largely immune to image distortions generated by susceptibility variations, chemical shift and paramagnetic impurities, unlike clinical magnetic resonance imaging methods. It enables systems with transverse lifetimes as short as tens of microseconds to be successfully visualized. Our experimental results show that most sedimentary rocks have a single exponential transverse magnetization decay for
T
*
2
, which suggests that quantitative imaging of local fluid content can be easily obtained. Some examples of MRI techniques are represented that reveal internal sedimentary characteristics and heterogeneity. In addition, the application of quantitative MRI techniques to examine flow mechanisms in rock cores is outlined.
The Janus database: providing worldwide access to ODP and IODP data
Authors: Mithal Rakesh , Becker David G.
Published: April 2008

In 1997, the Ocean Drilling Program began using a relational data management system and applications called Janus to store and retrieve data collected on the drill ship
JOIDES Resolution
. Since then many new web-based data access queries have been added, and some modifications to the database have been made. The database modifications were needed to allow the migration of pre-Janus data to the database, to incorporate modifications in the calibration procedures, to improve database performance, to add storage and access to various digital images, and to add access to scanned digital images of original paper data. These modifications were made by staff at Texas A&M University and reflect enhancements required by the Ocean Drilling Program (ODP) scientific community.

With the start of the Integrated Ocean Drilling Program (IODP) an opportunity exists to make additional enhancements to the existing Janus database. As such, two major areas are identified: developing a core description program(s) and providing data visualization tools for improved analysis. Efforts to use Java-based programs to build these enhancements are cited. Geographic information systems (GIS) technology is being explored as a viable approach to providing these enhancements.

Building an understanding of the Janus database is best accomplished by visiting the Web site
http://iodp.tamu.edu/database
. Available data can be reviewed using the online ‘Database overview’ option. A list of all queries that are available in Janus can be acquired through the online ‘Data search’ option.
Channel flow and continental collision tectonics: an overview
Authors: Grujic D.
Published: April 2008

The principle of channel flow as defined in fluid dynamics has been used in continental geodynamics since the 1980s. The basic equations for one-dimensional flow introduced to geologists by Turcotte and Schubert were further developed by several research groups to meet the needs of specific studies. The most substantive differences among numerical models are results of different solutions for flow in crust, developed for different boundary conditions. The concept of channel flow has met with strong opposition and criticism from geophysicists and modellers. Although it is difficult to prove unambiguously that there is an active weak channel, it is still the most successful model to explain and predict the tectonics, metamorphism and exhumation of high-grade terranes in some orogens. Moreover, the concept of channel flow has stimulated novel approaches to the study of both the tectonics and metamorphism of large, hot orogens and the interaction between tectonic and surface processes.
Mechanisms and timescales of felsic magma segregation, ascent and emplacement in the Himalaya
Authors: Scaillet B. , Searle M. P.
Published: April 2008

We combine field, petrological, geochemical and experimental observations to evaluate the timescales of compaction-driven and shear-assisted melt extraction and ascent in the Himalaya. The results show that melt migration via compaction and channelling is inescapable and operates on timescales of less than 1 million years and possibly as short as 0.1 million years. Field and petrological data show that such a fast and efficient melt transfer results from a combination of favourable factors, including: (1) low but constant melt viscosity (10
4.5
Pa s) during extraction and ascent; (2) grain size coarsening of the source rocks in response to prolonged heating prior to melting; and (3) high source fertility and thus high melt fraction, owing to elevated modal amounts of muscovite in leucogranite sources. All three factors dramatically increase source permeability. Calculations show that shear-assisted melt extraction had a time interval recurrence in the range 10 000–100 000 years (10–100 ka), leading to sill thicknesses of 1–30 m. Yet melts falling at the low end of the viscosity range when coupled to high shear velocities may lead to veins several hundred metres thick. The deepest structural levels (e.g. central Zanskar Range) show that
in-situ
melts formed where pure shear compaction was greatest and where simple shear was also operative. Magma extracted from migmatite leucosomes was injected along planes of weakness parallel to the ductile shear fabric, probably by some form of hydraulic fracturing crack propagation mechanism. Large High Himalayan leucogranite (HHL) bodies (e.g.
c.
5 km thick sills at Manaslu, Makalu and northern Bhutan) may thus represent inflated laccoliths assembled via dykes that tapped a 100–300 m melt layer produced by compaction of the Greater Himalayan Series (GHS). Thermal simulations show that such melt layers may have incubation times of several million years. Although transport time for magmas associated with the HHL is short, the time for assembly may take several million years for the largest HHL, as geochronological data indicate (up to 5 million years for Manaslu, Shisha Pangma). Transport of leucogranite melt from mid-crustal levels towards the surface was concomitant with active low-angle normal faulting along the South Tibetan Detachment (STD) normal fault, a structure that effectively formed the lid to the extrusion of a partially molten layer of mid-crustal rocks (channel flow). Rapid cooling of the granites emplaced at the top of the GHS implies rapid extrusion and lateral flow of GHS rocks beneath the STD during the period
c.
20–17 Ma. Weakening of the crust by partial melting is thus likely to be pulsatory in time, and future thermomechanical models should incorporate such aspects to model tectonic evolution of hot orogens.
The Appalachian Inner Piedmont: an exhumed strike-parallel, tectonically forced orogenic channel
Authors: Hatcher Robert D. , Merschat Arthur J.
Published: April 2008

The Appalachian Inner Piedmont (IP) extends along orogenic strike some 700 km from North Carolina to Alabama. Its physical attributes contrast with those of other Appalachian tectonic elements: gentle dip of dominant foliation; imbricate stack of fold nappes; dominant sillimanite-grade metamorphism and near ubiquitous migmatization; heterogeneous, non-plane deformation; and earlier S-foliations transposed to C-foliations southeast of the mid-Palaeozoic Brevard fault zone forming a 10–20 km wide amphibolite-facies shear zone along the western flank of the IP. The IP contains west- and SW-directed thrust sheets and mineral stretching lineation, sheath folds on all scales, and other indicators that define a curved crustal flow pattern throughout the belt. Field and modern geochronologic data confirm that the IP is not exotic. It contains a Laurentian component (eastern Tugaloo terrane) and an internal terrane (Cat Square) that contains both Laurentian and Gondwanan detrital zircons, separated by the Brindle Creek fault. Cat Square terrane rocks likely accumulated in a Devonian remnant ocean that closed beginning
c.
400 Ma.

The complex but consistently asymmetric, NW- to west- to SW-directed flow pattern throughout the IP reflects confinement beneath a > 15 km thick overburden produced during subduction of Cat Square and Laurentian components beneath the approaching Carolina superterrane along the Central Piedmont suture. Oblique NE-to-SW transpressive subduction to > 15 km depth initiated partial melting, forcing escape from the collision zone in an along-strike orogenic channel. The IP detached from rocks to the west of the mid-Palaeozoic Brevard fault zone as the collision zone tightened and the IP mass flowed
c.
200 km southwestward in the channel. The top of the channel is preserved at the NE end of the IP, and the base (Brevard fault zone) is preserved to the west and SW. As an exhumed orogenic channel, the curved IP flow paths may provide insight for middle to lower crustal deformation and flow in modern orogens.
The Campi Flegrei caldera: unrest mechanisms and hazards
Authors: De Natale G. , Troise C. , Pingue F. , Mastrolorenzo G. , Pappalardo L. , Battaglia M. , Boschi E.
Published: April 2008

In the last four decades, Campi Flegrei caldera has been the world’s most active caldera characterized by intense unrest episodes involving huge ground deformation and seismicity, but, at the time of writing, has not culminated in an eruption. We present a careful review, with new analyses and interpretation, of all the data and recent research results. We deal with three main problems: the tentative reconstruction of the substructure; the modelling of unrest episodes to shed light on possible pre-eruptive scenarios; and the probabilistic estimation of the hazards from explosive pyroclastic products. The results show, for the first time at a volcano, that a very peculiar mechanism is generating episodes of unrest, involving mainly activation of the geothermal system from deeper magma reservoirs. The character and evolution of unrest episodes is strongly controlled by structural features, like the ring-fault system at the borders of the caldera collapse. The use of detailed volcanological, mathematical and statistical procedures also make it possible to obtain a detailed picture of eruptive hazards in the whole Neapolitan area. The complex behaviour of this caldera, involving interaction between magmatic and geothermal phenomena, sheds light on the dynamics of the most dangerous types of volcanoes in the world.
Lateral collapse and tsunamigenic potential of marine volcanoes
Authors: McGuire W. J.
Published: April 2008

The predominantly constructive life cycles of large, long-lived, stratovolcanoes and basaltic shields are punctuated by transitory episodes during which large volumes of material are divested from the flanks. Such shedding typically takes place catastrophically in the form of a lateral collapse, generating a debris avalanche and leaving a scar that may attain caldera dimensions. Collapse may follow instability development arising from a single, discrete, event, such as a crypto-dome intrusion, or may be the end-product of progressive destabilization over a long period of time. Lateral collapses may also occur at persistent slumps, which may have been active over periods as long as 10
4
–10
5
a prior to catastrophic failure. Collapse velocities may exceed 40 m s
−1
, leading to completion of the process within a few hundreds of seconds. Collapse volumes span several orders of magnitude, ranging from less than 1 km
3
to more than 10 km
3
at many continental and subduction-zone volcanoes, to 1000 km
3
or more at the great basalt shields of Hawaii. Lateral collapse may be accompanied by a wide range of associated hazards, including atmospheric shock wave, pyroclastic flows and surges, extensive tephra fall, and secondary lahars. For volcanoes in the marine environment, potentially destructive and lethal tsunamis can be added to the inventory. Here, the potential for a lateral collapse at an ocean island volcano to generate a ‘mega-tsunami’ (more than 100 m high at source and destructive at oceanic distances) is discussed and evaluated.
Volcanic hazard assessment at the Campi Flegrei caldera
Authors: Mastrolorenzo G. , Pappalardo L. , Troise C. , Rossano S. , Panizza A. , de Natale G.
Published: April 2008

Previous and new results from probabilistic approaches based on available volcanological data from real eruptions of Campi Flegrei, are assembled in a comprehensive assessment of volcanic hazards at the Campi Flegrei caldera, in order to compare the volcanic hazards related to the different types of events. Hazard maps based on a very wide set of numerical simulations, produced using field and laboratory data as input parameters relative to the whole range of fallout and pyroclastic-flow events and their relative occurrence, are presented. The results allow us to quantitatively evaluate and compare the hazard related to pyroclastic fallout and density currents (PDCs) in the Campi Flegrei area and its surroundings, including the city of Naples.

Due to the dominant wind directions, the hazard from fallout mostly affects the area east of the caldera, and the caldera itself, with the level of probability and expected thickness decreasing with distance from the caldera and outside the eastern sectors. The hazard from PDCs decrease roughly radially with distance from the caldera centre and is strongly controlled by the topographic relief, which produces an effective barrier to propagation of PDCs to the east and northeast, areas which include metropolitan Naples. The main result is that the metropolitan area of Naples would be directly exposed to both fallout and PDCs. Moreover, the level of probability for critical tephra accumulation by fallout is relatively high, even for moderate-scale events, while, due to the presence of topographic barriers, the hazard from PDCs is only moderate and mostly associated with the largest events.
Intrinsic vulnerability of the Alburni karst system (southern Italy)
Authors: Ducci D.
Published: April 2008

In order to, respectively, assess the resource vulnerability and the source vulnerability of the Alburni karst system (southern Italy), the COP and VULK methods have been applied in the framework of the ‘European Approach’ as proposed in 2003 by the COST (Co-Operation in Science and Technology) 620 task group – Action: ‘Vulnerability and Risk Mapping for the Protection of Carbonate – Karst – Aquifers’. The Alburni massif, with more than 500 caves, is the most important karst area of southern Italy. The drainage network is not continuous; there are several endoreic basins and large zones without superficial drainage but with many sinking streams (streams disappearing into swallow holes) and dolines. The caves (more than 100), well explored by speleologists, directly communicate with the above mentioned infiltration areas. The most important ones are hierarchically well organized and extend over a wide area. Some of them recharge important springs with very short transit times. The final vulnerability map shows that the prevalent vulnerabilities are high and very high owing to the widespread karstification and the presence of large vegetated areas with gentle slopes that favour fast infiltration on the plateau.
Natural and anthropogenic rock collapse over open caves
Authors: Waltham T. , Lu Z.
Published: April 2008

Natural rock collapse that reaches the ground surface to form a collapse doline is relatively rare in limestone karst. The anthropogenic karst geohazard is posed by the possibility of rock collapse when additional loading is imposed by engineering works directly over a known or unknown cave. An intact rock-cover thickness that exceeds half the cave width appears to be safe in most karst terrains formed in strong limestone. Guidelines suggest that drilling or probing prior to construction should prove sound rock to depths ranging between 3 and 7 m in most of the various types of karst.
Sinkholes in Italy: first results on the inventory and analysis
Authors: Nisio S. , Caramanna G. , Ciotoli G.
Published: April 2008

The Italian Geological Survey (APAT) carried out field surveys and analysis of collapse phenomena (sinkholes) in Italy. The main goal of the project is to collect geological, geomorphological, geochemical and hydrogeological data about the sinkhole-prone areas in Italy in order to develop a spatial database of the characteristics of each phenomenon. The preliminary results of this study provide information on the distribution, geological setting, and monitoring and remediation actions associated with these natural collapses in Italy. Many Italian regions are affected by these natural disasters. Some of them are caused by karst collapses or anthropic activity. However, some occur in areas characterized by buried carbonate bedrock (up to 190 m), as well as by peculiar geological–structural and geochemical scenarios. In these areas it is not reasonable to ascribe the formation mechanism to karst activity. Instead, these types of cavities quickly develop in terrains with a variable granulometry, often in connection with upwelling fluids. In this work some natural specific cases have been studied in order to define the relationships between the geology (regional tectonic elements, mineral spring waters and strong gas vents) and the genesis of the sinkholes. A first attempt of sinkhole classification is also presented.
Karst processes and slope instability: some investigations in the carbonate Apennine of Campania (southern Italy)
Authors: Santo A. , Del Prete S. , Di Crescenzo G. , Rotella M.
Published: April 2008

Some investigations carried out in the Campania Region (southern Italy) are shown concerning instability phenomena, the development of which is strongly influenced by karst. The widespread presence of carbonate massifs close to important urban centres with dense road networks creates high-risk situations in many settings of this region.

Such phenomena can have very different dimensions, origin and geomorphological development, and can be traced back to the action of hypogean and epigean karst and to complex interactions with other erosional processes.

In particular, among the hypogean forms, we have analysed collapse sinkholes that have developed on carbonate slopes, especially along fault lines where there are aquifers and ascent of mineralized fluids, and which are sometimes connected to strong seismic events.

Among the forms connected to epikarst processes, the origin of pinnacles has been investigated. They are isolated rock pillars, whose origin depends on a particular interaction between the geostructural characteristics of the masses and the process of karstic dissolution.

Moreover, a wide variety of morphologies exist that are related to the interaction between epigean and hypogean karst and other typologies of erosional processes. Among these one group is represented by caves on carbonate slopes developed in cataclastic zones, where a slow karstic process leads to the formation of upwards caves, with dimensions of some decametres, and consequently to the high production of debris downhill. Similarly, this process has been observed along slopes set on talus. Finally, the complex combination of the karstic phenomenon with the erosional wave action forms both caves and natural rock arcs along the coasts.
The Effect of Galvanic Coupling Between Modern Fracture Fixation Constructs in Physiologically Relevant Solutions: The Role of Serum Proteins on the Corrosion of Ti6Al4V and 316L Alloys
Authors: Grebner Todd , Hansen D. C.
Published: April 2008

The corrosion behavior of 316L and Ti6Al4V standard 8-hole 3.5 millimeter small fragment locking compression plate and screw constructs immersed in Hanks Balanced Salt Solution (HBSS) modified with the addition of albumin and fibrinogen at concentrations similar to that found in human blood serum was investigated. Open circuit potential, DC polarization and electrochemical impedance spectroscopy techniques were used to measure four possible assembled configurations of the constructs (plate:screw): Ti6AL4V:Ti6Al4V, 316L:316L, Ti6Al4V:316L and 316L:Ti6Al4V. In addition, 168 hour (1 week) galvanic current measurements were made of the same plate:screw combinations. The results of this investigation indicate that the Ti6Al4V:Ti6Al4V plate and screw construct exhibited the lowest corrosion rate of the four possible construct combinations by an order of magnitude. Both of the mixed metal plate:screw constructs (Ti6Al4V:316L and 316L:Ti6Al4V) exhibited metal deposition onto the plates after the 1 week galvanic couple measurement. These results indicate that testing of the alloys in a physiologically relevant media may yield corrosion data that is more representative of the actual materials performance when implanted in the body.
Selective Dissolution of Ni from Nitinol for Increasing the Biocompatibility
Authors: Dalla Corte Daniel , Dick Luís Frederico P.
Published: April 2008

Different electrochemical surface treatments were applied to the Ni-Ti shape memory alloy and to pure Ti and Ni for comparison. Electrolytes containing complexing ions, as F- or Cl-, produced localized corrosion on Ni-Ti. However, by Rutherford backscattering spectroscopy and scanning electron microscopy a loss of nickel and morphological modifications of the surface were verified for Ni-Ti polarized in 1M H3PO4 or 1M H2SO4. Corrosion resistance improvement in Hank's solution was observed for the Ni-Ti alloy polarized at 3V in 1M H3PO4.
VUV Luminescence Due to 5d - 4f Transitions in Gd3+ and Lu3+ Ions Doped into Fluoride Crystals
Authors: Makhov Vladimir , Kirm Marco , Stryganyuk Gregory , Vielhauer Sebastian , Zimmerer Georg
Published: April 2008

High-resolution (< 1 Aå) VUV emission and excitation spectra as well as luminescence decay kinetics have been studied for several fluoride crystals containing Gd3+ and Lu3+ ions under excitation by synchrotron radiation. The obtained results evidently show that VUV luminescence (~ 10 eV) observed from these crystals originates from 5d-4f transitions in the Gd3+ and Lu3+ ions. Only fast spin-allowed 5d-4f luminescence is observed from Gd compounds, whereas both spin-forbidden and spin-allowed 5d-4f luminescence has been detected from Lu compounds, the latter being observed only at high enough (T > 100 K) temperatures.
Synthesis, Characterization and Luminescent Properties of [Tb(HMPA) 3(phen)] Complex
Authors: Kumar Rajesh , Khatkar Satyender P. , Makrandi J. K. , Singh Ishwar
Published: April 2008

The complex [Tb(HMPA)3(phen)] (where HMPA=2'-hydroxy-4'-methoxy-2-phenylacetophenone and phen =1,10-phenanthroline) was synthesized . Energy dispersive X-ray analysis (EDX) results showed the presence of terbium in the complex. This complex was further characterized by infra-red spectroscopy, thermal analysis, scanning electron microscopy (SEM) and elemental analysis. The synthesized complex emitted green luminescent with main peak at 546nm on exposure at 354nm.
The Role of LiF for the Electron Injection in tris-(8-hydroxyquinoline) Aluminum
Authors: Ding Huanjun J. , Gao Yongli
Published: April 2008

We have investigated the interface electronic structure of Al and Au deposition on LiF coated tris-(8-hydroxyquinoline) aluminum (Alq) using X-ray and ultraviolet photoemission spectroscopy. We observed that at the Al/LiF/Alq interface, a new state appears in the former energy gap and the highest occupied molecular orbital (HOMO) of Alq has a 1 eV downward shift, which explains the significant improvement in electron injection. In contrast, the Au/LiF/Alq interface shows a flat band situation and as a result, the electron injection barrier remains high. The difference between these two interfaces is attributed to the n-doping by Li released upon Al deposition, and the p-doping by Au that compensates for any possible Li release.
Development of Thiophene-based Polymeric Semiconductors for Printed Thin-Film Transistors
Authors: Wu Yiliang , Li Yuning , Liu Ping , Pan Hualong , Ong Beng
Published: April 2008

Recently, organic thin-film transistors (OTFTs) have received great interests as potentially low-cost alternative to hydrogenated α-Si transistors for applications in large-area, flexible, and ultra-low-cost electronics. The development of high mobility, solution- processable, and air-stable organic semiconductor is the key to achieve this transition. In this paper, we review structural studies and design of thiophene-based polymer semiconductors with respect to solution processability, ambient stability, molecular self-organization, and field-effect transistor properties for OTFT applications. We show that through delicately controlled pi-conjugation, strategically positioned pendant side-chain distribution, and carefully tailored side-chain length, novel solution-processable thiophene-based polymer semiconductors with mobility similar to the hydrogenated α-Si transistors and good ambient stability were developed.
Quasi-Static Capacitance-Voltage Characterizations of Mobile Ion Accumulation and Depletion Phenomena in Organic Thin-Film Transistors
Authors: Chen YiMing , Huang JianJang
Published: April 2008

By conducting C-V profile measurement, we analyzed the charge transport behavior in polycrystalline pentacene OTFTs. We found that carrier accumulation and depletion processes in the semiconductor channel layer is caused by a trap and de-trap mechanism. We apply such processes to explain C-V profiles at various gate voltages, ramp rates and sweep directions. At faster ramp rates, hysteresis can be observed from C-V profile. The phenomenon can be attributed to the asymmetry of the relaxation time of carrier trap and detrap mechanism. At the slower ramp rate, most carriers are able to interact with the gate stress, so the hysteresis disappears. And beyond this ramp rate, the corresponding threshold voltages are then kept at constant values, despite the existence of traps. Furthermore, low-mobility mobile ions or impurities participate in the charge accumulation and depletion when the ramp rate is much slower, which results in a skew of C-V profiles.