ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    facet.materialart.
    Unknown
    A nondestructive stratigraphic and radiographic neutron study of Lorenzo Ghiberti’s reliefs from paradise and north doors of Florence baptistery (2009)
    American Institute of Physics
    Details
    Publication Date: 2009-10-01
    Print ISSN: 0021-8979
    Electronic ISSN: 1089-7550
    Topics: Physics
    Published by American Institute of Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 2
    facet.materialart.
    Unknown
    Non destructive neutron diffraction measurements of cavities, inhomogeneities, and residual strain in bronzes of Ghiberti’s relief from the Gates of Paradise (2011)
    American Institute of Physics
    Details
    Publication Date: 2011-03-15
    Print ISSN: 0021-8979
    Electronic ISSN: 1089-7550
    Topics: Physics
    Published by American Institute of Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 3
    facet.materialart.
    Unknown
    A silicon photomultiplier readout for time of flight neutron spectroscopy with γ-ray detectors (2009)
    American Institute of Physics
    Details
    Publication Date: 2009-09-01
    Print ISSN: 0034-6748
    Electronic ISSN: 1089-7623
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Published by American Institute of Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 4
    facet.materialart.
    Unknown
    PML Absorbing Boundaries (2003)
    Seismological Society of America
    Details
    Publication Date: 2003-04-01
    Description: It has been previously demonstrated that no reflection is generated when elastic (or electromagnetic) waves enter a region with Perfectly Matching Layer (PML) absorbing conditions in a continuous medium. The practical application of PMLs, however, is in numerical modeling, where the medium is discretized by either a finite-element or a finite-difference scheme thus introducing a reduced amount of reflection. In such a case what is the practical and quantitative efficiency of PML absorbing boundaries? Assuming a regular spatial mesh, we start by evaluating analytically the reflection of body waves introduced by the discrete transition toward PML properties, under variable angle of incidence and wavelength. We then extend our evaluation with numerical tests for both body and Rayleigh waves. Surprisingly enough, the absorption remains equally efficient at wavelengths far larger than the PML thickness itself. As a consequence, the PML thickness can be kept minimal even for studies involving relatively low frequencies, and no rescaling with model size is required. Another pleasant feature is that it is all the more efficient at shallow angles of incidence. Finally, we show through numerical examples that a major advantage of using PMLs is their efficiency in absorbing Rayleigh waves at the free surface, a point where more classical methods perform rather poorly. Although previous authors essentially limited the description of their discrete implementation to 2D, we develop to some level of detail a 3D finite-difference scheme for PMLs and provide numerical examples.
    Print ISSN: 0037-1106
    Electronic ISSN: 1943-3573
    Topics: Geosciences , Physics
    Published by Seismological Society of America
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 5
    facet.materialart.
    Unknown
    Simulation of Earthquake Ground Motion and Effects on Engineering Structures during the Preeruptive Phase of an Active Volcano (2004)
    Seismological Society of America
    Details
    Publication Date: 2004-12-01
    Description: Several of the world's active volcanoes are located near densely populated areas, and therefore the seismic hazard associated with preeruptive earthquake activity and its relation to the potential damage of engineering structures should be considered as a part of risk evaluation and management. This is true for Mt. Vesuvius volcano (southern Italy), where several hundred thousand people are exposed to volcanic and related seismic risks. This study investigates the effect of preeruptive seismic activity through the massive simulation of earthquake waveforms in the magnitude, location, and focal-mechanism ranges expected for Mt. Vesuvius seismicity. Synthetics are processed to evaluate the characteristic strong-motion parameters, which are useful for estimating the seismic damage to a built-up environment that would arise from both the maximum expected single event and the cumulative effect of a large number of small events. Synthetic and observed strong-motion parameters for a selected set of recorded earthquakes are compared to validate the modeling approach. The scaling of the simulated peak ground acceleration (PGA) with distance appears to be influenced by earthquake depth, owing to the presence of a sharp velocity discontinuity at shallow depths underneath the Vesuvius area. On the other hand, the hysteretic energy spectrum, related to the plastic behavior of the structures, depends strongly on the b-parameter of the Gutenberg-Richter law (G-R). By varying the G-R law parameters across a reasonable expected range, we observe that the cumulative hysteretic energy is comparable to the values observed at near-source distances during the 1997 Umbria-Marche, Italy, event (M 5.8), which produced serious damage to buildings and infrastructure, although a significant PGA value was not recorded.
    Print ISSN: 0037-1106
    Electronic ISSN: 1943-3573
    Topics: Geosciences , Physics
    Published by Seismological Society of America
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 6
    facet.materialart.
    Unknown
    A Local Magnitude Scale for Southern Italy (2009)
    Seismological Society of America
    Details
    Publication Date: 2009-07-29
    Description: A local magnitude scale has been defined for southern Italy, in the area monitored by the recently installed Irpinia Seismic Network. Waveforms recorded from more than 100 events of small magnitude are processed to extract synthetic Wood-Anderson traces. Assuming a general description of peak-displacement scaling with the distance, by means of linear and logarithmic contributions, a global exploration of the parameter space is performed by a grid-search method with the aim of investigating the correlation between the two decay contributions and seeking for a physical solution of the problem. Assuming an L (super 2) norm, we found M=logA+1.79 log R-0.58 yielding an error on the single estimation smaller than 0.2, at least when the hypocenter location is accurate. Station corrections are investigated through the station residuals, referring to the average value of the magnitude. Using a z test, we found that some stations exhibit a correction term significantly different from 0. The use of the peak acceleration and peak velocity as indicators of the magnitude is also investigated.
    Print ISSN: 0037-1106
    Electronic ISSN: 1943-3573
    Topics: Geosciences , Physics
    Published by Seismological Society of America
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 7
    facet.materialart.
    Unknown
    Seismic Ambient Noise Analysis in Southern Italy (2012)
    Seismological Society of America
    Details
    Publication Date: 2012-03-29
    Description: We studied the ambient noise recorded at Irpinia Seismic Network (ISNet), a seismic network installed along the Campania-Lucania Apenninic chain (southern Italy), with the aim of characterizing the noise spectrum for each station as a function of time and the detection threshold of the network. For the latter purpose, we proposed a mixed indirect approach based on the signal-to-noise ratio (SNR) in the time domain, with parameterization in the frequency domain. The source signature is represented by the convolution of the Brune source time function with the Azimi attenuation curve. We found that 1.3 is the minimum magnitude an event should have to be detected at least at five stations with an SNR larger than five, wherever it occurs. We observed a space variability of the detection threshold as large as 0.3 units, ascribed to both the geometrical configuration of the network and the differences in the noise levels at the different stations. A sensitivity study indicates that the estimation of the detection threshold is robust for changes in the focal depths and stress drop, while it is strongly affected by the anelastic attenuation. In our case, changes of the reduced time t (super *) in the range 0.015-0.035 s generate changes in the completeness threshold of 0.5 units. Noise levels were obtained by a statistical analysis on the power spectral density curves along almost three years of continuous data from 22 stations. We found that, at short periods, major time variations are generated by diurnal changes in the wind intensity and other meteorological factors. At longer periods, we retrieved the microseismic peak, resulting from the constructive interference of oceanic waves. We also found an additional peak between 2 and 4 s, correlated with the sea wave height along the Tyrrhenian coast.
    Print ISSN: 0037-1106
    Electronic ISSN: 1943-3573
    Topics: Geosciences , Physics
    Published by Seismological Society of America
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 8
    facet.materialart.
    Unknown
    The Effectiveness of a Distant Accelerometer Array to Compute Seismic Source Parameters: The April 2009 L'Aquila Earthquake Case History (2011)
    Seismological Society of America
    Details
    Publication Date: 2011-01-26
    Description: The 6 April 2009 M (sub w) 6.3 L'Aquila earthquake, central Italy, has been recorded by the Irpinia Seismic Network (ISNet) about 250 km southeast of the epicenter. Up to 19 three-component accelerometer stations could be used to infer the main source parameters with different seismological methods. We obtained an approximate location of the event from arrival times and array-based back-azimuth measurements and estimated the local magnitude (6.1) from an attenuation relation for southern Italy. Assuming an omega-square spectral model, we inverted S-wave displacement spectra for moment magnitude (6.3), corner frequency (0.33 Hz), stress drop (2.5 MPa), and apparent stress (1.6 MPa). Waveform modeling using a point source and an extended-source model provided consistent moment tensors with a centroid depth around 6 km and a prevalently normal fault plane solution with a dominant directivity toward the southeast. The relatively high corner frequency and an overestimated moment magnitude of 6.4 from moment tensor inversions are attributed to the rupture directivity effect. To image the rupture geometry, we implemented a beamforming technique that back-projects the recorded direct P-wave amplitudes into the earthquake source region. A northwest-southeast striking rupture of 17 km length is imaged, propagating with an average velocity up to 3 km/s. This value is significantly higher than our estimate of 2.2 km/s from S-wave spectra. Our case study demonstrates that the use of array techniques and a dense accelerometer network can provide quick and robust estimates of source parameters of moderate-sized earthquakes located outside the network.
    Print ISSN: 0037-1106
    Electronic ISSN: 1943-3573
    Topics: Geosciences , Physics
    Published by Seismological Society of America
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 9
    facet.materialart.
    Unknown
    Kinematic Inversion of Strong-Motion Data Using a Gaussian Parameterization for the Slip: Application to the 2008 Iwate-Miyagi, Japan, Earthquake (2012)
    Seismological Society of America
    Details
    Publication Date: 2012-12-01
    Description: We present a nonlinear technique for the purpose of estimating the distribution of the final slip and the rupture velocity on the fault plane from the inversion of strong-motion records. In this work, the ground-motion simulation is obtained by evaluating the representation integral in the frequency domain, through a finite-element approach, based on a Delaunay's triangulation of the fault plane. The slip distribution is parameterized by a linear combination of 2D overlapping Gaussian functions. This choice allows us to relate the maximum frequency in the data to the smallest resolvable wavelength on the fault plane, insuring a smooth representation for the slip function. We investigate the capability of such a representation to describe complex slip maps, and we relate the width of the Gaussian function and the overlapping to the minimum wavelength of the slip function. The inverse problem is solved by a two-step procedure aimed at separating the computation of the rupture velocity from the evaluation of the slip distribution. While a global exploration is maintained for the rupture velocity, for each explored value of this quantity, the slip solution is computed as the best solution approaching the observations in the sense of the L2 norm. The nonlinear step is performed through the neighborhood algorithm (NA), while the linear one uses the nonnegative least-squares (NNLS) method. The technique has been applied to retrieve the rupture history of the 2008 Iwate-Miyagi, Japan, earthquake. The slip distribution is characterized by a large slip patch extending from the hypocenter to the southern shallow part of the fault plane, with a maximum amplitude of 6 m. In addition, a relatively smaller asperity is located in the north shallow part of the fault. We found that the rupture lasted about 12 s with an average rupture velocity of about 2.0 km/s.
    Print ISSN: 0037-1106
    Electronic ISSN: 1943-3573
    Topics: Geosciences , Physics
    Published by Seismological Society of America
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 10
    facet.materialart.
    Unknown
    The Effectiveness of a Distant Accelerometer Array to Compute Seismic Source Parameters: The April 2009 L'Aquila Earthquake Case History (2012)
    Seismological Society of America
    Details
    Publication Date: 2017-04-03
    Description: The seismic sequence that occurred in the Abruzzo Apennines near L’Aquila (Italy) in April 2009 caused extensive damage and a large number of casual- ties (more than 300). The earthquake struck an area in the Italian Apennines chain where several faults, belonging to adjacent seismotectonic domains, create a complex tectonic regime resulting from the interaction among regional stress buildup, local stress changes caused by individual earthquakes, and viscous-elastic stress relaxation. Understanding such complex interaction in the Apennines can lead to a large step for- ward in the seismic risk mitigation in Italy. The Abruzzo earthquake has been very well recorded by interferometric synthetic aperture radar (InSAR) data, much better than the first Italian earthquake ever recorded by satellites, namely, the 1997 Umbria–Marche earthquake. ENVISAT (ENVIronmental SATellite) data for the Abruzzo earthquake are, in fact, very clear and allow an accurate reconstruction of the faulting mechanism. We present here an accurate inversion of vertical deformation data obtained by ENVISAT images, aimed to give a detailed reconstruction of the fault geometry and slip distribu- tion. The resulting fault models are then used to compute, by a suitable theoretical model based on the elastic dislocation theory, the stress changes induced on the neigh- boring faults. The correlation of the subsequent mainshocks and aftershocks of the Abruzzo sequence with the volumes undergoing increasing Coulomb stress clearly evidence the triggering effect of coseismic stress changes on further seismicity. More- over, this analysis put in evidence which seismotectonic domains have been more heav- ily charged by stress released by the Abruzzo mainshocks. The most important faults significantly charged by the Abruzzo sequence belong to the Sulmona and Avezzano tectonic domains. Taking into account the average regional stress buildup in the area, the positive Coulomb stress changes caused by this earthquake can be seen as antici- pating the next earthquakes in the neighboring domains of 15–20 yr.
    Description: Published
    Description: 2340-2354
    Description: JCR Journal
    Description: restricted
    Keywords: Aquila Earthquakes of April 2009 ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER (OA)
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...