Contribution of Geographical Information Systems to the Management of Volcanic Crises

The incorporation of a set ofcomputer-based tools, such as Geographical InformationSystems and physical models, to the field of riskassessment, introduces a new perspective in thevolcanic risk maps production, increasing the analysisand modelling capabilities available through theapplication of conventional methodologies. Amethodology adapted to the requirements andcharacteristics of the new operating environment hasbeen applied at Tenerife island (Canary Islands,Spain) to carry out a study devoted to analyse thesuitability of these tools for near real-timemanagement of volcanic crises. With this in mind, aseries of potential eruption scenarios have beenselected to identify and characterise which elementsat risk would prove most vulnerable against a specificvolcanic phenomenon, depending on the socio-economiccharacteristics of the area affected and the resultingdistribution of the volcanic products. This kind ofinformation is fundamental to update, adapt or produceeffective risk management and emergency plans orprotocols, where the measures to mitigate or fightagainst a specific volcanic disaster have to be taken,incorporating the existing knowledge of the phenomenonbehaviour and taking into account their potentialeffects on the area of interest.     

On outlier-hiding effects in specific Gauss–Markov models: geodetic examples

 A specific subclass of Gauss–Markov models has been defined as containing the models for which the disturbance/response matrix, determined under the assumption of uncorrelated observations, consists of independent diagonal blocks. A proposed modification of reliability assessment procedure for such models is presented By the appropriate reduction of a given full covariance matrix for the observations, the proposal allows the assessment to be made in the resulting model which, in contrast to the initial model, is free from outlier-hiding effects of the type not occurring in ordinary models. The theoretical findings are demonstrated using simple numerical examples. All the proofs supporting the proposal are gathered in Appendixes. The proposal, which is not without its own weak points, is an attempt to associate the reliability assessment in specific Gauss–Markov models with effective outlier detection. Received: 23 June 1998 / Accepted: 5 July 2000     

Truncated Collimated Flows in Abell 30, Abell 78 and the Honeycomb Nebula

Localised collimated flows of ionized gas are found in two hydrogen deficient planetary nebulae, Abell 30 and Abell 78 as well as in the Honeycomb complex of interlocking shells in halo of 30 Dor in the Large Magellanic Cloud. One common feature of these flows, in seemingly disparate objects, is that they all terminate at around the same difference in radial velocity (with respect to that of the systemic radial velocity). A possible explanation involves high speed flows being decelerated by mass-loading. In Abell 30 and 78, mass is injected by clumps embedded in the fast wind. In the Honeycomb nebula, a supernova blast wave has pierced an old dense shell wall which adds mass to the post-shock flow via a boundary layer. This revised version was published online in July 2006 with corrections to the Cover Date.     

Astrophysical Molecules AlD and CaH: Transition Probabilities and Dissociation Energy

The Franck-Condon (FC) factors and r-centroids for the bands systemC ¹ Σ ⁺ → X ¹ Σ ⁺ of AlD and E ² Π → X ² Σ ⁺ of CaH have been evaluated by means of a reliable numerical integration procedure by using a suitable potential. The dissociation energy, D _e, for the electronic ground states of AlD and CaH have been estimated by the curve fitting method to the RKRV experimental potential curve turning out to be 3.01 eV and 2.32 eV, respectively. This revised version was published online in July 2006 with corrections to the Cover Date.     

A multi‐system geochronology in the Ad‐3 borehole,Pannonian Basin (Hungary) with implications for dating volcanic rocks by low‐temperature thermochronology and for interpretation of (U–Th)/He data

Independent geochronological and thermal modelling approaches are applied to a biostratigraphically exceptionally well‐controlled borehole, Alcsútdoboz‐3 (Ad‐3), in order to constrain the age of Cenozoic geodynamic events in the western Pannonian Basin and to test the efficacy of the methods for dating volcanic rocks. Apatite fission track and zircon U–Pb data show two volcanic phases of Middle Eocene (43.4–39.0 Ma) and Early Oligocene (32.72 ± 0.15 Ma) age respectively. Apatite (U–Th)/He ages (23.8–14.8 Ma) and independent thermal and subsidence history models reveal a brief period of heating to 55–70 °C at ~17 Ma caused by an increased heat‐flow related to crustal thinning and mantle upwelling. Our results demonstrate that, contrary to common perception, the apatite (U–Th)/He method is likely to record ‘apparent’ or ‘mixed’ ages resulting from subsequent thermal events rather than ‘cooling’ or ‘eruption’ ages directly related to distinct geological events. It follows that a direct conversion of ‘apparent’ or ‘mixed’ (U‐Th)/He ages into cooling, exhumation or erosion rates is incorrect.