Earthquakes in Switzerland and surrounding regions during 2004

This report of the Swiss Seismological Service summarizes the seismic activity in Switzerland and surrounding regions during 2004. During this period, 677 earthquakes and 96 quarry blasts were detected and located in the region under consideration. With 22 events with M_L≥2.5, the seismic activity in the year 2004 was close to the average over the last 30 years. As in previous years, most of the activity was concentrated in the Valais and in Graubünden. In addition, several moderate earthquakes occurred in the lower crust below the northern Alpine foreland. Unusual was that five earthquakes were sufficiently strong to cause ground shaking of intensity IV over large portions of the territory. Two were located in Switzerland (Liestal, M_L 3.8, and Brugg, M_L 4.0). The epicenters of the other three strong events were located outside Switzerland (Besan?on in the French Jura, M_L 4.8, Waldkirch in southern Germany, M_L 5.1, and Lago di Garda in northern Italy, M_L 5.3).     

A review of calcareous nannofossil astrobiochronology encompassing the past 25 million years

This paper presents a review of (astrobiochronological) calibration of Recent to late Oligocene calcareous nannofossil datum events. Biohorizons included in the paper are those of the widely used “standard” nannofossil zonations of Martini, E. [1971. Standard Tertiary and Quaternary calcareous nannoplankton zonation. In: Farinacci, A. (Ed.), Proceedings of the Second International Conference on Planktonic Microfossils Roma. Rome, Ed. Tecnosci. vol. 2, pp. 739–785], and Okada, H., and Bukry, D. [1980. Supplementary Modification and Introduction of Code Numbers to the Low-Latitude Coccolith Biostratigraphy Zonation (Bukry, 1973, 1975). Marine Micropaleontology 51, 321–325], as well as supplementary biohorizons proposed in the literature. The biohorizons have been selected on the basis of the unambiguous taxonomy of the index taxa and their biostratigraphic usefulness. We emphasise the application of rigorous methodology in nannofossil studies which permits an evaluation of biohorizons in terms of reliability, and calibrates their potential correlatability. Astrochronological age estimates rely on the Geologic timescale developed by the ICS in 2004, with some new calibrations included. We provide an overview of the relative position of biohorizons versus the astronomically calibrated ages of magnetic reversals and reference isotope stratigraphies. Surprisingly, there are still few high-resolution quantitative biostratigraphic studies of astrochronologically tuned sections in spite of the central role of such studies in addressing fundamental problems such as the tempo and mode of plankton evolution.     

Quaternary intraplate deformation in the southeastern Sierras Pampeanas, Argentina

Neogene strain from the subducting Nazca plate is widely distributed in theAndean foreland as a result of flat-lying subduction beneath central westernArgentina (28^°–33^°S latitude). This fact is indicated byuplifted basement blocks bounded by reverse faults as far as 600 kms eastof the Chilean trench axis. Some deformation in the southern Sierras deCórdoba (southeastern Sierras Pampeanas) indicates significantdisplacements during Quaternary and even late Holocene time. Thisregion has low to moderate seismicity characterized by earthquakemagnitudes 6.7 with no associated noticeable surface ruptures.This paper presents information recently gathered on the most conspicuousregional structures of the area (El Molino, Sierra Chica and Las Lagunasfaults). The last movement along the El Molino fault thrust basement rocksover organic-rich (0.8–1.3 ka) sediment and fault relationships suggestprevious Quaternary displacements. Along the Sierra Chica fault,Precambrian basement has been thrust a minimum of 13.5 m overPleistocene conglomerates, and faulting also affects latePleistocene-Holocene fluvial sediments. The Las Lagunas fault has beenregarded as the source of the 1934 Ms 5.5 and 6.0 earthquakes, whichheavily damaged the nearby village of Sampacho. The faulted surface isburied under Holocene loess, but its trace is expressed as a 24-km-longrectilinear scarp, despite continuous modification due to land use.Although we lack detailed information on probable rupture lengths duringlarge Sierras Pampeanas thrust earthquakes, some preliminary considerationsare made for the regional seismic hazard of these structures. The geologicevidence described here identifies these faults as possible sources of strongearthquakes in the future.     

Three Reflection Telescopes for Wide Field Space Astronomy. First Results from a 30 cm Prototype and Prospects

We present the basic concepts of the two-mirror, three-reflection optical system (2MTRT), and discuss the important benefits of such a system for space projects: wide ( 2^°) correctedand unvignetted FOV, without the use of refractive optics for thefield correction, planarity of the focal surface for an optimizedinstallation of wide area detectors, easy telescope adjustement, small volume and little mass.We also report the results of optical tests made with a 30 cm prototype,equipped with a 2k × 2k CCD camera, and give examples of scientific programmes which can be performed from space and in hostile terrestrial sites such as the Antarctic Plateau.     

Water-table and discharge changes associated with the 2016–2017 seismic sequence in central Italy: hydrogeological data and a conceptual model for fractured carbonate aquifers

A seismic sequence in central Italy from August 2016 to January 2017 affected groundwater dynamics in fractured carbonate aquifers. Changes in spring discharge, water-table position, and streamflow were recorded for several months following nine Mw 5.0–6.5 seismic events. Data from 22 measurement sites, located within 100 km of the epicentral zones, were analyzed. The intensity of the induced changes were correlated with seismic magnitude and distance to epicenters. The additional post-seismic discharge from rivers and springs was found to be higher than 9 m³/s, totaling more than 0.1 km³ of groundwater release over 6 months. This huge and unexpected contribution increased streamflow in narrow mountainous valleys to previously unmeasured peak values. Analogously to the L’Aquila 2009 post-earthquake phenomenon, these hydrogeological changes might reflect an increase of bulk hydraulic conductivity at the aquifer scale, which would increase hydraulic heads in the discharge zones and lower them in some recharge areas. The observed changes may also be partly due to other mechanisms, such as shaking and/or squeezing effects related to intense subsidence in the core of the affected area, where effects had maximum extent, or breaching of hydraulic barriers.

     

Intrinsic groundwater vulnerability assessment: issues,comparison of different methodologies and correlation with nitrate concentrations in NW Italy

The concept of aquifer vulnerability is certainly useful in the field of groundwater protection. Nevertheless, within the scientific community, the definition of vulnerability is still under debate and lacks standardisation. As a consequence, the methods for evaluating the vulnerability degree are numerous and often lead to conflicting results. Thus, in this study, three methods that are commonly used in groundwater vulnerability assessments due to their easy application (namely DRASTIC, GOD and TOT) were utilised in four areas of the Piedmont region (NW Italy). The results obtained by the different methods were compared and correlated with the nitrate concentrations in the groundwater. The aims of the study were (i) to evaluate the effectiveness of the adopted methods and their comparability, (ii) to discuss the limits of the intrinsic vulnerability methods and (iii) to verify the applicability of nitrate as a tracer in the assessment of groundwater vulnerability or explain the reasons why it is not applicable. It was observed that the three intrinsic vulnerability methods are not able to uniquely identify the most or least vulnerable areas. Additionally, the comparison of the intrinsic vulnerability indexes only occasionally showed a reasonable correlation. Furthermore, there was no clear correlation between the vulnerability indexes and nitrate concentrations in the groundwater. These results could be explained by several reasons: (1) the methods are mostly based on the level of groundwater protection provided by the overlaying lithologies and do not consider the physical processes occurring in the aquifer; (2) the intrinsic vulnerability methods only consider vertical pathways for contaminants, but a pre-existing contaminant could be present in the aquifer; (3) groundwater nitrate concentrations are affected by the nitrate input and surplus; and (4) nitrates are subject to physical and biological attenuation in aquifers and cannot necessarily be considered stable tracers in the assessment of groundwater vulnerability.     

Asbestos and other fibrous minerals contained in the serpentinites of the Gimigliano-Mount Reventino Unit (Calabria,S-Italy)

Serpentinites are metamorphic rocks with good technological properties and valuable ornamental characteristics, which have been exploited since ancient times. Actually, their use is limited and monitored in several countries worldwide because they can contain fibrous asbestos minerals that may be carcinogenic. Furthermore, certain types of fibrous minerals can be confused with asbestos, and must therefore be carefully investigated. We have investigated the possible presence of the asbestos and non-asbestos fibrous phases contained in serpentinitic rocks in a meta-ophiolitic sequence from the Gimigliano-Mount Reventino Unit (Southern Italy), which had not been previously assessed. The detection and quantification of asbestos and the correct distinction of the fibrous non-asbestos minerals are very important not only from a scientific point of view, but also from a legislative one. This is especially the case for the administrative agencies that have to take decisions with regards to the implementation of public and occupational health protection measures (e.g., in road yards and quarry excavations). As a consequence of this, serpentinitic rock samples have been characterized in detail through X-ray powder diffraction, scanning and transmission electron microscopy combined with energy-dispersive spectrometry, analytical electron microscopy (SEM–EDS and TEM–AEM), differential scanning calorimetry, thermogravimetry and micro-Raman spectroscopy. Two kinds of asbestos and four kinds of non-asbestos fibrous silicates have been detected in the examined samples. In order of decreasing abundance these are polygonal serpentine, chrysotile, fibrous antigorite, tremolite, gedrite and magnesiohornblende. The size, morphology, crystallinity and chemical composition of the fibres were also discussed, in the light of the possible role these properties could play in the carcinogenic effect on human health.     

Earthquakes in Switzerland and surrounding regions during 2009

This report of the Swiss Seismological Service summarizes the seismic activity in Switzerland and surrounding regions during 2009. During this period, 450 earthquakes and 68 quarry blasts were detected and located in the region under consideration. The three strongest events occurred about 15 km NW of Basel in southern Germany (M_L 4.2), near Wildhaus in the Toggenburg (M_L 4.0) and near Bivio in Graubünden (M_L 3.5). Although felt by the population, they were not reported to have caused any damage. With a total of 24 events with M_L ≥ 2.5, the seismic activity in the year 2009 was close to the average over the previous 34 years.     

Application of Binary Permeability Fields for the Study of $${\hbox {CO}_{2}}$$ Leakage from Geological Carbon Storage in Saline Aquifers of the Michigan Basin

The feasibility of geological carbon storage (GCS) sites depends on their capacity to retain safely \({\hbox {CO}_{2}}\). While deep saline formations and depleted gas/oil reservoirs are good candidates to sequester \({\hbox {CO}_{2}}\), gas/oil reservoirs typically have a limited storage capacity compared to ideal targets (\(\sim \) 1 Mt/year) considered for \({\hbox {CO}_{2}}\) disposal (Celia et al. in Water Resour Res 51(9):6846–6892, 2015. doi: 10.1002/2015WR017609). In this respect, deep saline aquifers are considered more appropriate formations for GCS, but present the disadvantage of having limited characterization data. In particular, information about the continuity of the overlying sealing formations (caprock) is often sparse if it exists at all. In this work, a study of \({\hbox {CO}_{2}}\) leakage is conducted for a candidate GCS site located in the Michigan Basin, whose sealing properties of the caprock are practically unknown. Quantification of uncertainty on \({\hbox {CO}_{2}}\) leakage from the storage formation is achieved through a Monte Carlo simulation approach, relying on the use of a computationally efficient semi-analytical leakage model based upon the solution derived by Nordbotten et al. (Environ Sci Technol 43(3):743–749, 2009), which assumes leakage occurs across “passive” wells intersecting caprock layers. A categorical indicator Kriging simulator is developed and implemented to represent the caprock sealing properties and model the permeability uncertainty. Binary fields of caprock permeability are generated and exhibit mostly low permeability, with sparsely-occurring local high permeability areas where brine and \({\hbox {CO}_{2}}\) may leak out of the storage formation. In addition, the feasibility of extending the use of the semi-analytical model to large-area leakage pathways is studied. This work advances a methodology for preliminary uncertainty quantification of \({\hbox {CO}_{2}}\) leakage at sites of GCS with little or no information on the sealing properties of the caprock. The implemented analysis shows that, for the considered site, \({\hbox {CO}_{2}}\) leakage may not be negligible even for relatively low (\(\sim \) 1%) probabilities of finding permeable inclusions in the caprock and highlights the importance of being able to characterize caprock sealing properties over large areas.