Slip-rates of blind thrusts in slow deforming areas: examples from the Po Plain (Italy)

We calculate Plio-Pleistocene slip rates on the blind thrusts of the outer Northern Apennines fronts, that are the potential sources of highly damaging earthquakes, as shown by the MW 6.1-6.0, 2012 Emilia-Romagna seismic sequence. Slip rates are a key parameter for understanding the seismogenic potential of active fault systems and assessing the seismic hazard they pose, however, they are difficult to calculate in slow deforming areas like the Po Plain where faulting and folding is mostly blind. To overcome this, we developed a workflow which included the preparation of a homogeneous regional dataset of geological and geophysical subsurface information, rich in Plio- Pleistocene data. We then constructed 3D geological models around selected individual structures to decompact the clastic units and restore the slip on the fault planes. The back-stripping of the differential compaction eliminates unwanted overestimation of the slip rates due to compactioninduced differential subsidence. Finally, to restore the displacement we used different methods according to the deformation style, i.e. Fault Parallel Flow for faulted horizons, trishear and elastic dislocation modeling for fault-propagation folds. The result of our study is the compilation of a slip rate database integrating former published values with 28 new values covering a time interval from the Pliocene to the present. It contains data on 14 individual blind thrusts including the Mirandola thrust, seismogenic source of the 29 May 2012, MW 6.0 earthquake. Our study highlights that the investigated thrusts were active with rates ranging between 0.1-1.0 mm/yr during the last 1.81 Myr. The Mirandola thrust slipped at 0.86±0.38 mm/yr during the last 0.4 Myr. These rates calculated with an homogeneous methodology through the entire Po Plain can be charged entirely to the thrust activity and not to secondary effects like the differential compaction of sediments across the structures

The Long Term Optical Variability of the BL Lac object S5 0716+714: Evidence for a Precessing Jet

We present the historic light curve of the BL Lac object S5 0716+714, spanning the time interval from 1953 to 2003, built using Asiago archive plates and our recent CCD observations, together with literature data. The source shows an evident long term variability, over which well known short term variations are superposed. In particular, in the period from 1961 to 1983 the mean brightness of S5 0716+714 remained significantly fainter than that observed after 1994. Assuming a constant variation rate of the mean magnitude we can estimate a value of about 0.11 magnitude/year. The simultaneous occurrence of decreasing ejection velocities of superluminal moving components in the jet reported by Bach et al. (2005) suggests that both phenomena are related to the change of the direction of the jet to the line of sight from about 5 to 0.7 degrees for an approximately constant bulk Lorentz factor of about 12. A simple explanation is that of a precessing relativistic jet, which should presently be close to the smallest orientation angle. One can therefore expect in the next ten years a decrease of the mean brightness of about 1 magnitude.Comment: to appear on The Astronomical Journal, 17 pages, 7 figures. Fig.2 is given as a separated jpg fil

Deriving thrust fault slip rates from geological modeling: examples from the Marche coastal and offshore contraction belt, Northern Apennines, Italy.

We present a reconstruction of the central Marche thrust system in the central-northern Adriatic domain aimed at constraining the geometry of the active faults deemed to be potential sources of moderate to large earthquakes in this region and at evaluating their long-term slip rates. This system of contractional structures is associated with fault-propagation folds outcropping along the coast or buried in the offshore that have been active at least since about 3Myr. The ongoing deformation of the coastal and offshore Marche thrust system is associated with moderate historical and instrumental seismicity and recorded in sedimentary and geomorphic features. In this study, we use subsurface data coming from both published and original sources. These comprise cross-sections, seismic lines, subsurface maps and borehole data to constrain geometrically coherent local 3D geological models, with particular focus on the Pliocene and Pleistocene units. Two sections crossing five main faults and correlative anticlines are extracted to calculate slip rates on the driving thrust faults. Our slip rate calculation procedure includes a) the assessment of the onset time which is based on the sedimentary and structural architecture, b) the decompaction of clastic units where necessary, and c) the restoration of the slip on the fault planes. The assessment of the differential compaction history of clastic rocks eliminates the effects of compaction-induced subsidence which determine unwanted overestimation of slip rates. To restore the displacement along the analyzed structures, we use two different methods on the basis of the deformation style: the fault parallel flow algorithm for faulted horizons and the trishear algorithm for fault-propagation folds. The time of fault onset ranges between 5.3-2.2 Myr; overall the average slip rates of the various thrusts are in the range of 0.26-1.35 mm/yr

Indoor air pollution and respiratory diseases: A general update and a Portuguese perspective

Objective: To quantify the impact of different air pollutants on respiratory health based on robust estimates based on international data and to summarise the evidence of associations between indoor exposure to those pollutants and respiratory morbidity in the Portuguese population. Results: Several systematic reviews and meta-analyses (MA) at the world level demonstrate the impact of indoor air quality on respiratory health, with indoor particulate matter and gasses exerting a significant effect on the airways. Volatile organic compounds (VOC) have been related to asthma and lung cancer. However, only meta-analyses on biomass use allowed documentation of long-term respiratory effects. While early publications concerning Portuguese-based populations mainly focused on indoor exposure to environmental tobacco smoke, later studies relocated the attention to relevant exposure environments, such as day care buildings, schools, residences and nursing homes. Looking at the pooled effects from the reviewed studies, high levels of carbon dioxide and particulate matter in Portuguese buildings were significantly associated with asthma and wheezing, with VOC and fungi showing a similar effect in some instances. Conclusions: Despite the significant reduction of indoor air pollution effects after the 2008 indoor smoking prohibition in public buildings, studies show that several indoor air parameters are still significantly associated with respiratory health in Portugal. The country shares the worldwide necessity of standardisation of methods and contextual data to increase the reach of epidemiological studies on household air pollution, allowing a weighted evaluation of interventions and policies focused on reducing the associated respiratory morbidity.proofepub_ahead_of_prin

Optical and Radio monitoring of S5 1803+74

The optical (BVRI) and radio (8.4 GHz) light curves of S5 1803+784 on a time span of nearly 6 years are presented and discussed. The optical light curve showed an overall variation greater than 3 mag, and the largest changes occured in three strong flares. No periodicity was found in the light curve on time scales up to a year. The variability in the radio band is very different, and shows moderate oscillations around an average constant flux density rather than relevant flares, with a maximum amplitude of $\sim$30%, without a simultaneous correspondence between optical and radio luminosity. The optical spectral energy distribution was always well fitted by a power law. The spectral index shows small variations and there is indication of a positive correlation with the source luminosity. Possible explanations of the source behaviour are discussed in the framework of current models.Comment: 25 pages, 12 figure

919 Thunderstorm asthma in the mediterranean area: seasonal weather and effect on health for outdoor workers

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Historic Light Curve and Long-term Optical Variation of BL Lacertae 2200+420

In this paper, historical optical(UBVRI) data and newly observed data from the Yunnan Observatory of China(about100 years) are presented for BL Lacertae. Maximum variations in UBVRI: 5.12, 5.31, 4.73, 2.59, and 2.54 and color indices of U-B = -0.11 +/- 0.20, B-V= 1.0 +/- 0.11, V-R= 0.73 +/- 0.19, V-I= 1.42 +/- 0.25, R-I= 0.82 +/- 0.11, and B-I= 2.44 +/- 0.29 have been obtained from the literature; The Jurkevich method is used to investigate the existence of periods in the B band light curve, and a long-term period of 14 years is found. The 0.6 and 0.88 year periods reported by Webb et al.(1988) are confirmed. In addition, a close relation between B-I and B is found, suggesting that the spectra flattens when the source brightens.Comment: 21 pages, 6 figures, 2 table, aasms4.sty, to be published in ApJ, Vol. 507, 199