Spectral Indices of Stars at Super-solar Regime

We derived Lick narrow-band indices for 139 candidate super metal-rich stars of different luminosity class previously studied in Malagnini et al. (2000). Indices include Iron Fe50, Fe52, Fe53, and Magnesium Mgb and Mg2 features. By comparing observations with Kurucz' synthetic model atmospheres, no evidence is found for non-standard Mg vs. Fe relative abundance (i.e. [Mg/Fe]~ 0, on the average, for our sample). A comparison with the Worthey et al.(1994) and Buzzoni et al.(1992, 1994) fitting function predictions for [Fe/H] > 0 is performed and briefly discussed.Comment: 4 pages, 3 figures; proceedings of "New Quests in Stellar Astrophysics: The link between Stars and Cosmology", 26-30 March, 2001, Puerto Vallarta, Mexico, eds. M. Chavez, A. Bressan, A. Buzzoni & D. Mayya, to be published by the Kluwer Academic Publisher

Lick Spectral Indices for Super Metal-rich Stars

The Lick Fe5015, Fe5270, Fe5335, Mgb and Mg2 indices are presented for 139 candidate SMR stars of different luminosity class studied in Malagnini et al. (2000). Evidence is found for a standard (i.e. [Mg/Fe]~0) Mg vs. Fe relative abundance. Both the Worthey et al. (1994) and Buzzoni et al. (1992, 1994) fitting functions are found to suitably match the data at super-solar metallicity regimes. See http://www.merate.mi.astro.it/~eps/home.html for further details.Comment: 16 pages with 11 figures (Aastex format). To appear in the Nov. '01 issue of the PAS

ShakeMap implementation in Italy

Since 2005, the Italian Civil Protection (Dipartimento della Protezione Cilvile, DPC) has funded several projects driven toward fast assessment of ground motion shaking in Italy - the final goal being that of organizing the emergency and direct the search and rescue (SAR) teams. To this end, the Istituto Nazionale di Geofisica e Vulcanologia (INGV) has started to determine shakemaps using the USGS-ShakeMap package within 30 minutes from event occurrence and adopting a manually revised location. In this paper we present the INGV implementation of USGS-ShakeMap for earthquakes occurring in Italy and immediately neighboring areas. Emphasis is put on data acquisition, the adopted ground motion predictive relations and the site corrections for the local amplifications of the ground motion. Finally, two examples of shakemaps are shown - the first determined for a recent medium size earthquake, the other for the large Irpinia, 1980, M6.9 event. For both events, the maps are compared to the available macroseismic data

foF2 prediction in Rome observatory

A prediction procedure of the hourly values of the critical frequency of the F2 ionospheric layer, foF2, based on the local geomagnetic index ak, is presented. The geomagnetic index utilised is the time-weighted accumulation magnetic index ak(τ) based on recent past history of the index ak. It is utilised an empirical relationship between the log(NmF2(t)/ NmF2M), where NmF2(t) is the hourly maximum electron density at the F2 peak layer and NmF2M is its 'quiet' value, and the time weighted magnetic index. The prediction of foF2 is calculated during periods of severe magnetic activity in the current solar cycle 23 in Rome observatory

High-Frequency Attenuation in the Lake Van Region, Eastern Turkey

We provide a complete description of the characteristics of excitation and attenuation of the ground motion in the Lake Van region (eastern Turkey) using a data set that includes three-component seismograms from the 23 October 2011 Mw 7.1 Van earthquake, as well as its aftershocks. Regional attenuation and source scaling are parameterized to describe the observed ground motions as a function of distance, frequency, and magnitude. Peak ground velocities are measured in selected narrow frequency bands from 0.25 to 12.5 Hz; observed peaks are regressed to define a piecewise linear regional attenu- ation function, a set of excitation terms, and a set of site response terms. Results are modeled through random vibration theory (see Cartwright and Longuet-Higgins, 1956). In the log–log space, the regional crustal attenuation is modeled with a bilinear geo- metrical spreading g r characterized by a crossover distance at 40 km: g r ∝ r^−1 fits our results at short distances (r < 40 km), whereas g r ∝ r^−0.3 is better at larger distances (40 < r < 200 km). A frequency-dependent quality factor, Q f =100( f/fref)^ 0:43 (in which fref 1.0 Hz), is coupled to the geometrical spreading. Because of the inherent trade-off of the excitation/attenuation parameters (Δσ and κ), their specific values strongly depend on the choice made for the stress drop of the smaller earthquakes. After choosing a Brune stress drop ΔσBrune 4 MPa at Mw 3:5, we were able to define (1) an effective high frequency, distance- and mag- nitude-independent roll-off spectral parameter, κeff = 0:03 s and (2) a size-dependent stress-drop parameter, which increases with moment magnitude, from ΔσBrune 4 MPa at Mw 3.5 to ΔσBrune 20 MPa at Mw 7.1. The set of parameters mentioned here may be used in order to predict the earthquake-induced ground motions expected from future earthquakes in the region surrounding Lake Van

Site amplification estimates in the Garigliano valley, central Italy, based on dense array measurements of ambient noise

A frequency-domain formulation of the Aki (1957, 1965) autocorrelation method has been applied to seismic noise recorded by a 100-m wide circular array deployed on soft Holocene sediments in the Garigliano river valley, where a large amplification of ground motion during earthquakes was experienced (Rovelli et al., 1988). The application of this method to ambient noise recordings demonstrates that microtremors in the valley are dispersive and dominated by surface waves. By assuming that the vertical component reflects Rayleigh wave motion, we obtain a dispersion curve that is interpreted in terms of a layered shear-wave velocity structure. Layer thicknesses are constrained by the stratigraphic information provided by a deep hole drilled in the area, and shear velocities are estimated by means of a trial-and-error approach to achieve a satisfactory fit of the ambient noise dispersion. The best-fit velocity model is used to compute a theoretical transfer function, which is then compared with an average spectral ratio obtained from earthquake weak ground motions recorded at two stations, one in the valley and the other on a limestone reference site. An overall agreement is found between the theoretical curve and the observed spectral ratios. The discrepancies that do exist may be ascribed to the assumption of 1-D inhomogeneity which considerably simplifies the theoretical transfer function. Our results show that the spatial-correlation method can be useful to infer velocity structure down to depths of hundreds of meters, when generalized geological informations are available, and can thus provide useful constraints for theoretical methodologies for the prediction of site response

Uncertainty analysis for seismic hazard in Northern and Central Italy

In this study we examine uncertainty and parametric sensitivity of Peak Ground Acceleration (PGA) and 1-Hz Spectral Acceleration (1-Hz SA) in probabilistic seismic hazard maps (10% probability of exceedance in 50 years) of Northern and Central Italy. The uncertainty in hazard is estimated using a Monte Carlo approach to randomly sample a logic tree that has three input-variables branch points representing alternative values for bvalue, maximum magnitude (Mmax) and attenuation relationships. Uncertainty is expressed in terms of 95% confidence band and Coefficient Of Variation (COV). The overall variability of ground motions and their sensitivity to each parameter of the logic tree are investigated. The largest values of the overall 95% confidence band are around 0.15 g for PGA in the Friuli and Northern Apennines regions and around 0.35 g for 1-Hz SA in the Central Apennines. The sensitivity analysis shows that the largest contributor to seismic hazard variability is uncertainty in the choice of ground-motion attenuation relationships, especially in the Friuli Region (∼0.10 g) for PGA and in the Friuli and Central Apennines regions (∼0.15 g) for 1-Hz SA. This is followed by the variability of the b-value: its main contribution is evident in the Friuli and Central Apennines regions for both 1-Hz SA (∼0.15 g) and PGA (∼0.10 g). We observe that the contribution of Mmax to seismic hazard variability is negligible, at least for 10% exceedance in 50-years hazard. The overall COV map for PGA shows that the uncertainty in the hazard is larger in the Friuli and Northern Apennine regions, around 20-30%, than the Central Apennines and Northwestern Italy, around 10-20%. The overall uncertainty is larger for the 1-Hz SA map and reaches 50- 60% in the Central Apennines and Western Alps

Side-effects of a number of insecticides on predatory mites in apple orchards

Background: Amblyseius andersoni is a common predatory mite occurring in fruit orchards located in Europe and North America. Its role in preventing spider mite outbreaks is widely recognized, in particular when selective pesticides are used. The compatibility between plant protection products and predatory mites is crucial to preserve their activity. There is a need to investigate the effects of pesticides on beneficials using multiple approaches. Objectives: Field and laboratory experiments were conducted to evaluate the effects of a number of insecticides on A. andersoni. Methods: The effects of neonicotinoids (i.e., acetamiprid, imidacloprid, thiacloprid, thia-methoxam) were compared with those of pyrethroids (i.e., tau-fluvalinate), well known for their negative impact on predatory mites. Insecticides were applied 1-3 times in an experimental fruit orchard located in Northern Italy. Laboratory trials focused on their effects on the survival and the fecundity of predatory mite females. Results: Field experiments showed a decline in predatory mite numbers in plots treated with neonicotinoids or tau-fluvalinate compared to the untreated control. However, predatory mites in neonicotinoid plots reached higher densities compared to those recorded in tau-fluvalinate plots. Spider mite (Panonychus ulmi) populations reached moderate to high densities in plots treated with tau-fluvalinate while their densities were negligible in the remaining plots. Amblyseius andersoni survival was moderately affected by some neonicotinoids in the laboratory while they significantly reduced predatory mite fecundity. In contrast tau-fluvalinate exerted severe effects on survival and fecundity of predatory mites. Finally, escaping rate increased after pesticide exposure suggesting possible alterations in predatory mite behavior. Conclusions: Neonicotinoid applications significantly affected predatory mite densities in field conditions and this phenomenon appeared to be influenced by their impact on female fecundity. Their effects on survival were less severe. Implications of these results for IPM tactics in fruit orchards are discusse

A regional ground motion excitation/attenuation model for the San Francisco region

By using small-to-moderate-sized earthquakes located within ~200 km of San Francisco, we characterize the scaling of the ground motions for frequencies ranging between 0.25 and 20 Hz, obtaining results for geometric spreading, Q(f), and site parameters using the methods of Mayeda et al. (2005) and Malagnini et al. (2004). The results of the analysis show that, throughout the Bay Area, the average regional attenuation of the ground motion can be modeled with a bilinear geometric spreading function with a 30 km crossover distance, coupled to an anelastic function exp(-pi*f*r/V*Q(f)) , where: Q(f)=180f^0.42. A body-wave geometric spreading, g(r)= r^-1.0, is used at short hypocentral distances (r < 30 km), whereas g(r)= r^-0.6 fits the attenuation of the spectral amplitudes at hypocentral distances beyond the crossover. The frequency-dependent site effects at 12 of the Berkeley Digital Seismic Network (BDSN) stations were evaluated in an absolute sense using coda-derived source spectra. Our results show: i) the absolute site response for frequencies ranging between 0.3 Hz and 2.0 Hz correlate with independent estimates of the local magnitude residuals (dML) for each of the stations; ii) moment-magnitudes (MW) derived from our path and site-corrected spectra are in excellent agreement with those independently derived using full-waveform modeling as well as coda-derived source spectra; iii) we use our weak-motion-based relationships to predict motions region wide for the Loma Prieta earthquake, well above the maximum magnitude spanned by our data set, on a completely different set of stations. Results compare well with measurements taken at specific NEHRP site classes; iv) an empirical, magnitude-dependent scaling was necessary for the Brune stress parameter in order to match the large magnitude spectral accelerations and peak ground velocities with our weak-motion-based model

Near real time regional moment tensor estimation using italian broadband stations

Since 2002, the Istituto Nazionale di Geofisica e Vulcanologia (INGV) in Rome has started the installation of a high quality regional broadband network throughout the Italian territory. Up today, the network consists of 125 stations equipped with 40 s natural period instruments. The dense station coverage allows for the implementation of real-time regional moment tensor (MT) estimation procedures such as that proposed by Dreger and Helmberger (1993). The automatic MT algorithm uses real-time broadband waveforms continuously telemetered to INGV, and it is triggered for events with magnitude greater than Ml 3.5. This is the lowermost value for which we have found it possible to obtain reliable MT determination in the frequency band used in the inversion. The automatic solution is available within about 3-5 minutes after the earthquake location. Each solution has an assigned quality factor dependent on the number of the station used in the inversion, and the godness of fit between synthetic and observed data. MT is published on the web after revision by a seismologist. Efforts are also made to evaluate MT solutions for earthquakes occurring in Italy and neighboring regions in the last years. The results are compared to those obtained from application of other moment tensor methods. It is always found a good agreement between the newly determined solutions and those from other methods. Overall, fast and accurate moment tensor solutions are an important ingredient when attempting to estimate the recorded ground shaking. Overall, in Italy, earthquakes in the magnitude range 3.5 – 5 are very common; the availability of their focal mechanisms allows the mapping of the principal stress field axes leading to a better understanding of the ongoing tectonics