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  • Articles  (69)
  • 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques  (65)
  • Chemistry
  • 2005-2009  (69)
  • 1980-1984
  • 1955-1959
  • 1945-1949
  • 2006  (69)
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  • 2005-2009  (69)
  • 1980-1984
  • 1955-1959
  • 1945-1949
Year
Journal
Topic
  • 1
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    Synthetic seismicity for the San Andreas fault (2006)
    Details
    Publication Date: 2021-06-09
    Description: Because historical catalogs generally span only a few repetition intervals of major earthquakes, they do not provide much constraint on how regularly earthquakes recur. In order to obtain better recurrence statistics and long-term probability estimates for events M ? 6 on the San Andreas fault, we apply a seismicity model to this fault. The model is based on the concept of fault segmentation and the physics of static dislocations which allow for stress transfer between segments. Constraints are provided by geological and seismological observations of segment lengths, characteristic magnitudes and long-term slip rates. Segment parameters slightly modified from the Working Group on California Earthquake Probabilities allow us to reproduce observed seismicity over four orders of magnitude. The model yields quite irregular earthquake recurrence patterns. Only the largest events (M ? 7.5) are quasi-periodic; small events cluster. Both the average recurrence time and the aperiodicity are also a function of position along the fault. The model results are consistent with paleoseismic data for the San Andreas fault as well as a global set of historical and paleoseismic recurrence data. Thus irregular earthquake recurrence resulting from segment interaction is consistent with a large range of observations.
    Description: JCR Journal
    Description: open
    Keywords: seismicity ; model ; San Andreas fault ; seismic hazard ; fault segments ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
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    Rupture history of the 1997 Umbria-Marche (Central Italy) main shocks from the inversion of GPS, DInSAR and near field strong motion data (2006)
    INGV
    Details
    Publication Date: 2021-01-05
    Description: We investigate the rupture history of the three largest magnitude earthquakes of the 1997 Umbria-Marche sequence by inverting GPS, DInSAR and near-source strong motion waveforms. We use the frequency domain inversion procedure proposed by Cotton and Campillo (1995) and calculate the Green s functions for a layered halfspace using the discrete wavenumber and reflectivity methods. We first invert GPS measurements and DInSAR interferograms to image the coseismic slip distribution on the fault planes in a layered half space for the two earthquakes that occurred on September 26, 1997 at 00:33 UTC (Mw = 5.7) and 09:40 UTC (Mw = 6.0) near Colfiorito. We also invert DInSAR interferograms to infer the slip distribution during the subsequent earthquake that occurred on October 14, 1997 at 15:23 UTC (Mw = 5.6) in the SE section of the seismogenic zone near Sellano. We also explore the set of acceptable solutions using a genetic algorithm to have information on the available resolution of geodetic data. The slip models obtained by geodetic data inversion are used to perform a forward modeling of strong motion waveforms for all three events. We adopt a constant rupture velocity of 2.6 km/s and a constant rise time of 1 s. Our results show that these rupture models provide an acceptable fit to recorded waveforms. Finally, we invert the recorded ground displacements, collected during the September 26th 09:40 main shock and the October 14th Sellano earthquake, to constrain the rupture history. We use the geodetic slip distribution as starting model for the iterative inversion procedure. The retrieved rupture models are consistent with those inferred from geodetic data and yield a good fit to recorded seismograms. These rupture models are characterized by a heterogeneous slip distribution and an evident rupture directivity in agreement with previous observations.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: slip history ; waveform inversion ; geodetic data modeling ; Colfiorito earthquakes ; kinematic source models ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques ; 05. General::05.01. Computational geophysics::05.01.03. Inverse methods ; 05. General::05.02. Data dissemination::05.02.02. Seismological data
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
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    Ricostruzione geometrica del bacino di sansepolcro dell'interpretazione di profili di sisma a riflessione (2006)
    Details
    Publication Date: 2017-04-04
    Description: We have reconstrated the geometry of the Altotiberino Basin, near Sansepolcro based on the interpretation of a set of reflection seismic profiles. The profiles cross the basin from SW to NE and from NW to SE. The Southern section of the basin has been already analyzed because of crossed by the CROP-03 seismic profiles (Barchi et al., 1998).
    Description: Unpublished
    Description: Rome, 2005
    Description: open
    Keywords: seismic profiles ; 04. Solid Earth::04.02. Exploration geophysics::04.02.06. Seismic methods ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 4
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    Appunti di Sismometria (2006)
    Details
    Publication Date: 2017-04-03
    Description: Istituto Nazionale di Geofisica e Vulcanologia
    Description: Submitted
    Description: open
    Keywords: Seismometry ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: report
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  • 5
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    Management of Historical Seismic Data Using GIS: The Island of Ischia (Southern Italy) (2006)
    Kluwer Academic Publishers
    Details
    Publication Date: 2017-04-04
    Description: This paper presents the results of the use of Geographic Information Systems (GIS) in managing information on the effects of earthquakes in historical times on the island of Ischia. The unpublished sources on the Casamicciola earthquake of 28 July 1883 and the extensive bibliography documenting the island’s seismicity from 1228 showed the need to proceed towards a type of data storage that would also allow management of the same data. Application of GIS techniques allowed us to insert, extract, handle, manage and analyse the data for the zoning of seismic damage on the island of Ischia. The end-product consists of information layers, such as maps of isoseismals, the damage, and hazard involved, as well as numerical tables associated to maps. The study was developed using GIS Arc-View 3.2 software (ESRI) and is structured in thematic vectorial levels and rasters. The overlapping themes constitute a cartographic data base of the island. The damaged sites are located on a map at a scale of 1:10,000, with all the information on the 1883 earthquake (total number of houses, number of collapsed houses, collapsed or damaged rooms, photographs, plans of buildings, etc.) being associated to each site. The GIS is structured in such a way as to be able to be integrated with further georeferenced data and with other databases. It is thus able to provide support both for in-depth analyses of the dynamic processes on the island and extend the assessment to other natural risks (volcanic, landslides, flooding, etc.).
    Description: Published
    Description: 379–393
    Description: partially_open
    Keywords: Historical seismicity ; GIS ; seismic hazard ; island of Ischia ; 04. Solid Earth::04.06. Seismology::04.06.05. Historical seismology ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 6
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    WP8 Modelling of topographic signal: New software for the analysis of landscape response to faulting (2006)
    Details
    Publication Date: 2017-04-04
    Description: Slow active faults are inherently defined as faults that produce little displacement over geological time. This characteristic implies that the signature of such fault at the surface is very subtle and thus difficult to detect. One challenging strategy to tackle the problem of identifying elusive tectonic re-cords is the careful inspection of sensitive features in the landscape through quantificational methods. This approach assumes that even the faintest modification of the ground surface due to tectonics af-fects the development of recognizable landscape features. The ever increasing availability of comput-ing machines and detailed Digital Elevation Models (DEM) encourages the usage of dedicated soft-ware to speed up the geomorphic/tectonic analysis and mapping. The next sections will illustrate a suite of three original software tools dedicated at analysing the response of the landscape to the tec-tonic forcing caused by slip at depth on seismogenic faults. This process of analysis includes the fol-lowing main steps: (1) detection of sensitive landscape features; (2) parameterisation of seismogenic faults; and (3) modelling landscape evolution.
    Description: Istituto Nazionele di Geofisica e Vulcanoilogia (Rome, Italy) European Commission Research Directorates General Shared Cost
    Description: Published
    Description: open
    Keywords: new software ; faults ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: report
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  • 7
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    Seismic rotation waves: basic elements of theory and recording (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: Returning to the old problem of observed rotation effects, we present the recording system and basic elements of the theory related to the rotation fi eld and its association with seismic waves. There can be many different causes leading to observed/recorded rotation effects; we can group them as follows: generation of micro-displacement motion due to asymmetry of source processes and/or due to interaction between seismic body/surface waves and medium structure; interaction between incident seismic waves and objects situated on the ground surface. New recording techniques and advanced theory of deformation in media with defects and internal (e.g., granular) structure make it possible to focus our attention on the fi rst group, related to microdisplacement motion recording, which includes both rotation and twist motions. Surface rotations and twists caused directly by the action of emerging seismic waves on some objects situated on the ground surface are considered here only in the historical aspects of the problem. We present some examples of experimental results related to recording of rotation and twist components at the Ojcow Observatory, Poland, and L'Aquila Observatory, Italy, and we discuss some prospects for further research.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: rotation seismograph ; asymmetric stresses ; defect density ; self-rotation nuclei ; rotation and twist motions ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 8
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    Effects of the 6th September 2002 earthquake: damage amplification in the south-eastern sector of Palermo explained by GIS technology (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: During the 6th September 2002 earthquake the highest damage level in Palermo was observed in the SE sector. This is a recent urbanization area where reinforced concrete structures predominate. A detailed analysis of soil properties in Palermo was carried out by City-GIS to investigate a possible role of nearsurface geology on earthquake effects. City-GIS is a tool dedicated to natural hazard evaluation in urban areas. The availability of high density of well log data (stratigraphic and geotechnical) allowed a realistic modeling of surface geology and physical-mechanical properties that control the seismic response. In wide zones of the above mentioned sector of Palermo, outcropping terrains are composed of thin calcarenite layers, lying above remarkably thick siltyclayey sands that overlay the Numidian Flysch, commonly considered the bedrock of Quaternary sediments. Since silty-clayey sands feature greater deformability properties (Young's modulus) and smaller resistance properties (undrained cohesion and shear resistance angle) than Numidian Flysch, these zones of the SE sector exhibit high values of the acoustic impedance contrast. Moreover, a quite wide portion of the study area, crossed by the Oreto River, is characterized by very thick alluvial deposits. Here, the significant lateral variations of the lithostratigraphic geometry may be an additional cause of strong site effects.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: GIS ; seismic response ; site effects ; Palermo ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 9
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    Minimum 1D velocity models in Central and Southern Italy: a contribution to better constrain hypocentral determinations (2006)
    Details
    Publication Date: 2019-11-04
    Description: We computed one-dimensional ( I D) velocity models and station corrections for Centrai and Southern Italy, in- verting re-picked P-wave alTival times recorded by the Istituto Nazionale di Geofisica seismic network. The re-picked data yield resolved P-wave velocity results and proved to be more suited than bulletin data for de- tailed tomographic studies. Using the improved velocity models, we relocated the most significant earthquakes which occurt.ed in the Apennines in the past 7 years, achieving constrained hypocentral determinations for events within most of the Apenninic belt. The interpretation of the obtained lD velocity models allows us to infer interesting features on the deep structure of the Apennines. Smooth velocity gradients with depth and low P-wave velocities are ob,'ierved beneath the Apennines. We believe that our results are effective to constrain hypocentral locations in Italy and may represent a first step towards more detailed seismotectonic analyses.
    Description: JCR Journal
    Description: open
    Keywords: Earthquake location ; 1D velocity model ; Italian peninsula ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 10
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    Ray synthetic seismograms: a useful tool in the International Data Center environment (2006)
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    Publication Date: 2019-11-04
    Description: In this paper some of the results of a feasibility study on ray synthetic seismograms usage are reported. A computational method, ways of composing synthetic traces, an application of the source wavelet and the radiation pattern and integration of such an approach into the Center for Seismic Studies (CSS) revision 3.0 structure are outlined. Further on, results obtained for model examples, nuclear explosions, and earthquakes are presented. Conclusions of the undertaken feasibility study help to understand that ray synthetic seismograms represent a very fast tool (results in “no time”) and simultaneously represent a complex tool with all needed features. The ray synthetic seismograms can be implemented in various ways: to be computed automatically and used within the Intelligent Monitoring System, to be computed automatically and provided to the analyst, to provide a database of master events, to be computed interactively by an analyst during routine daily analysis.
    Description: JCR Journal
    Description: open
    Keywords: seismology ; synthetic seismograms ; data processing ; nuclear explosion ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 11
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    Comparison between LDG-network and GERESS-array with respect to regional detection and location results (2006)
    Details
    Publication Date: 2019-11-04
    Description: The design of a global seismic system to monitor compliance with a ban on underground nuclear testing considerably deviates from previous concepts of international seismic data exchange. The new concept relies on centralized processing of continuous data from a fixed station network (“alpha” stations) which provides the primary detection and location capability. This alpha station network is augmented by additional stations (“beta” stations) which send data on request to refine the hypocentres of events which were detected by the alpha network. To test this concept we have used the GERESS array in Germany as a prototype alpha station and investigated its regional detection and location capability for events in France and surrounding areas. For this region, data from the national French network operated by LDG provide an excellent reference data base. Within a 5 degree distance, GERESS showed an excellent performance in terms of detection and location down to magnitude M(LDG) = 3. Between a 5 degree and 10 degree distance, the detection capability is still high but very often it is not sufficient to locate events below M(LDG) = 4. Generalizing these results, we can conclude that either the maximum distance between alpha stations should be 10 degrees or the contribution of beta stations has to play a significant role in a future monitoring system.
    Description: JCR Journal
    Description: open
    Keywords: locations ; array ; seismic monitoring ; alpha stations ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 12
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    Amplitude response of a telemetered seismic system from seismometers to digital acquisition system (2006)
    Details
    Publication Date: 2019-11-04
    Description: Automated amplitude response of the complete seismometer, telemetry and recording system js obtaiued trom sinusoidal inputs to the calibration coil. Custom-built software was designed to perform fully automatic cali- bration analyses of the digital signals. In this paper we describe the signals used for calibration and interactive and batch procedures designed to obtain calibration functions in automatic mode. By using a steady-state method we reach a high degree of accuracy in the determination of both the frequency and amplitude of the \ignal. The only parameters required by this procedure are the seismometer mass, the calibration-coil constant and the intensity of the current injected into the calibration coil. This procedure is applicable to telemetered seismic systems and represents an optimization of the processing time. The software was designed to requjre no modification" jf the device used to generate the sinusoidal current should change. In particular, it is possi- ble to changc the number of monotrequcncy packages transmitted to the calibration coil with the on]y restric- tion that the difference between the frequency of two consecutjve packages be greater than 5%; for these rea- sons the procedure is expected to be usefu] for the seismological community. The paper inc]udes a generaI de- scription of thc designing criteria, and of the hardware and software architecture, as well as an account of thc system's performancc during a two year period of operation.
    Description: JCR Journal
    Description: open
    Keywords: transfer function ; seismic network ; calibration method ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 13
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    An analytic method for separating local from regional effects on macroseismic intensity (2006)
    Details
    Publication Date: 2019-11-04
    Description: nterpretation of macroseismic data is hazardous, due to its qualitative nature. This, linked with errors in eval- uation,) and the variations of local intensity, makes it difficult to draw valid conclusions. This study presents a statistical method as the basis for distinguishing the diverse components that constitute a macroseismic field. The method is based on the polar transformation of the coordinate system and on the analysis of the fractal di- mension of the intensity values, exposed to the gradually increasing action of a two-dimensional filter. The fractal dimension is shown to be an ideaI parameter with which to measure out the filtering process in order to separate the local components from the regional trend. This method has been applied to two Italian events and to an earthquake which took pIace in the Former Yugoslavian Republic of Macedonia (FYROM).
    Description: JCR Journal
    Description: open
    Keywords: macroseismic intensity ; fractal dimension ; filtering ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 14
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    The Ebre Observatory seismological station: past and present instrumentation and noise conditions (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: A review of the past and present instrumentation at Ebre Observatory seismological station (EBR) is presented in this work. In order to assess the quality of EBR from the point of view of modern seismic instrumentation site requirements, the noise conditions at EBR are also investigated by means of velocity power spectral density analysis in the frequency band 0.01〈 f 〈15 Hz by exploiting the three component broadband and digital data processing current capability. A correlation between noise levels and meteorological conditions at the site is observed, using the data of a complete meteorological station located a few tens of meters from the seismic cave. Results show that for long periods ( f 〈 0.04 Hz) and wind speeds ranging from 0 to 15.5 m/s, seismic noise levels may vary up to 45 dB for the horizontal components. These variations are related to tilts due to wind-generated pressure fl uctuations. Secondly, the seasonal variation of noise levels at the frequency band 0.04 〈 f 〈 0.3 Hz is characterized, obtaining that the amplitude of the seasonal variation is higher for secondary (up to 52 dB) than for primary (up to 44 dB) microseisms. On the other hand, a seasonal variation of the frequency of the three-component main noise peak is also suggested in this site and its variation is opposite to the velocity power spectral density amplitude evolution. Finally, a correlation between wind speed and seismic background noise is also observed at high frequencies.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: EBR station ; instrumentation ; seismic noise ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 15
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    Seismic damage in historic town centres and attenuation criteria (2006)
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    Publication Date: 2019-11-04
    Description: The structural significance of the damage scenarios characteristic of VIII and IX degrees on the MKS macroseismic scale is discussed with reference to the seismic behaviour of the buildings which make up the urban fabric of a historic town or city. In an VIII degree scenario, damage is limited to structurally precarious situations, while a IX degree scenario involves seismic damage to external walls. Mechanical interpretation of these scenarios provides the basis for intervention strategies sufficiently well defined as to constitute a guide for seismic damage prevention programmes. VIII degree damage is prevented by identifying precarious situations. while IX degree damage requires systematic action. A proposal is put forward for the clarification of seismic regulations and the usefulness of evaluating future earthquakes in macroseismic terms with reference to the safety requirements of new buildings is discussed.
    Description: JCR Journal
    Description: open
    Keywords: Italy ; Historical towns ; assessment of macroseismic intensity ; intervention strategies ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 16
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    Detection capability of the Italian network for teleseismic events (2006)
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    Publication Date: 2019-11-04
    Description: The future GSE experiment is based on a global seismic monitoring system, that should be designed for monitoring compliance with a nuclear test ban treaty. Every country participating in the test will transmit data to the International Data Center. Because of the high quality of data required, we decided to conduct this study in order to determine the set of stations to be used in the experiment. The Italian telemetered seismological network can detect all events of at least magnitude 2.5 whose epicenters are inside the network itself. For external events the situation is different: the capabilíty of detection is conditioned not only by the noise condition of the station, but also by the relative position of epicenter and station. The ING bulletin (January 1991-June 1992) was the data set for the present work. Comparing these data with the National Earthquake Information Center (NEIC) bulletin, we established which stations are most reliable in detecting teleseismic events and, moreover, how distance and back-azimuth can influence event detection. Furthermore, we investigated the reliability of the automatic acquisition system in relation to teleseismic event detection.
    Description: JCR Journal
    Description: open
    Keywords: teleseismic detections ; network detection capability ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 17
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    A comparison of two methods for earthquake source inversion using strong motion seismograms (2006)
    Details
    Publication Date: 2019-11-04
    Description: In this paper we compare two time-domain inversion methods that have been widely applied to the problem of modeling earthquake rupture using strong-motion seismograms. In the multi-window method, each point on the fault is allowed to rupture multiple times. This allows flexibility in the rupture time and hence the rupture velocity. Variations in the slip-velocity function are accommodated by variations in the slip amplitude in each time-window. The single-window method assumes that each point on the fault ruptures only once, when the rupture front passes. Variations in slip amplitude are allowed and variations in rupture velocity are accommodated by allowing the rupture time to vary. Because the multi-window method allows greater flexibility, it has the potential to describe a wider range of faulting behavior; however, with this increased flexibility comes an increase in the degrees of freedom and the solutions are comparatively less stable. We demonstrate this effect using synthetic data for a test model of the Mw 7.3 1992 Landers, California earthquake, and then apply both inversion methods to the actual recordings. The two approaches yield similar fits to the strong-motion data with different seismic moments indicating that the moment is not well constrained by strong-motion data alone. The slip amplitude distribution is similar using either approach, but important differences exist in the rupture propagation models. The single-window method does a better job of recovering the true seismic moment and the average rupture velocity. The multi-window method is preferable when rise time is strongly variable, but tends to overestimate the seismic moment. Both methods work well when the rise time is constant or short compared to the periods modeled. Neither approach can recover the temporal details of rupture propagation unless the distribution of slip amplitude is constrained by independent data.
    Description: JCR Journal
    Description: open
    Keywords: earthquake source inversion ; rupture propagation ; strong ground motion ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 18
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    Broad-band moment tensor inversion from single station, regional surface waves for the 1990, NW-Iran earthquake sequence (2006)
    Details
    Publication Date: 2019-11-04
    Description: e present a method for the inversion of complete waveforms in the 5-30 mHz frequency band for moment tensor determination. The method is based on the calibration of phase and group velocity dispersion curves for Rayleigh and Love fundamental modes to account for heterogeneous lithospheric structure, and is applied to the analysis of single station records of the VSL MEDNET station for the 1990 NW Iran earthquake sequence (the events of June 20, 21 and 24). The revised seismic moment of the June 20, 1990 Iranian earthquake is Mo = 1.56 x 1027 dyne-cm, corresponding to Mw = 7.4. The method proves to be a very robust tool for the analysis of moderate and large earthquakes at regional distances, producing consistent moment tensor solutions trom single station inversions in narrow (2-4 mHz) and wide (up to 20 mHz) frequency bands across the whole band of interest.
    Description: JCR Journal
    Description: open
    Keywords: seismic moment ; inversion techniques ; regional waveform analysis ; 1990 NW-Iran seismicity ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 19
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    Estimation of strong ground motion in broad-frequency band based on a seismic source scaling model and an empirical Green's function technique (2006)
    Details
    Publication Date: 2019-11-04
    Description: We introduce a generalized method for simulating strong ground motion from large earthquakes by summing subevent records to follow the ?2 law. The original idea of the method is based on a constant stress parameter between the target event and the subevent. It is applicable to a case where both events have a different stress drop after some manipulation. However, the simulation for a very large earthquake from a small event with this method has inevitably some deficiencies of spectral amplitudes in the intermediate frequency range deviating f`rom the ?2 model, although the high and low frequency motions match the scaling. We improve the simulation algorithm so as not to make spectral sags, introducing self-similar distribution of subfaults with different sizes in the fault plane, so-called fractal composite faulting model. We show successful simulations for intermediate-sized earthquakes (MJMA = 5.0, 6.0 and 6.1), the large aftershocks of the 1983 Akita-Oki earthquake. using the records of smaller aftershocks (MJMA = 3.9 and 5.0) as an empirical Green's function. Further, we attempted to estimate strong ground motion for the 1946 Nankai earthquake with Mw 8.2, using the records of a MJMA 5.1 earthquake occurring near the source region of the mainshock. We found that strong ground motions simulated for the fractal composite faulting model with two asperities radiating significantly high frequency motions matched well the observed data such as the near-field displacement record, the source spectrum estimated from the teleseismic record, and the seismic intensity distribution during the 1946 Nankai earthquake.
    Description: JCR Journal
    Description: open
    Keywords: empirical Green's function ; strong ground motion ; scaling law ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
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    A prototype radonmeter for seismic surveillance (2006)
    Details
    Publication Date: 2019-11-04
    Description: A new 222Rn monitoring prototype has been designed, assembled and tested at the Istituto Nazionale di Geofisica (ING) specifically addressed to seismic surveillance tasks, exploiting environmental monitoring, etc. It operates with an a scintillation technique (photomultiplier + Lucas Cell) coupled with a water input system, that lets continuous dehumidified gas flow, stripped from groundwater under monitoring. Several laboratory tests have been carried out to check the stability and versatility of the system; moreover statistical tests have been accomplished on several data sets obtained with an 241Am radioactive standard source, to check stability of the photomultiplier. A customised water flow system has been developed to perform both the highest efficiency and lowest influence of external noise parameters. This new prototype is very cheap and will be integrated within the new multiparametric geochemical monitoring system GMS II, that is currently being developed at ING, specifically designed for geochemical surveillance of seismic events.
    Description: JCR Journal
    Description: open
    Keywords: 222Rn continuous monitoring ; geochemical earthquake prediction ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
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    A microseismic study in a low seismicity area of Italy: the Città di Castello 2000-2001 experiment (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: Recent seismological studies contribute to better understand the first order characteristics of earthquake occurrence in Italy, identifying the potential sites for moderate to large size earthquakes. Ad hoc passive seismic experiments performed in these areas provide information to focus on the location and geometry of the active faults more closely. This information is relevant for assessing seismic hazard and for accurately constraining possible ground shaking scenarios. The area around the Città di Castello Basin, in the Northern Apennines (Central Italy), is characterized by the absence of instrumental seismicity (M 〉 2.5), it is adjacent to faults ruptured by recent and historical earthquakes. To better understand the tectonics of the area, we installed a dense network of seismic stations equipped with broadband and short period seismometers collecting data continuously for 8 months (October 2000-May 2001). The processing of ~ 900 Gbyte of data revealed a consistent background seismicity consisting of very low magnitude earthquakes (ML 〈 3.2). Preliminary locations of about 2200 local earthquakes show that the area can be divided into two regions with different seismic behaviour: an area to the NW, in between Sansepolcro and Città di Castello, where seismicity is not present. An area toward the SE, in between Città di Castello, Umbertide and Gubbio, where we detected a high microseismicity activity. These findings suggest a probable different mechanical behaviour of the two regions. In the latter area, the seismicity is confined between 0 and 8 km of depth revealing a rather well defined east-dipping, low angle fault 35 km wide that cuts through the entire upper crust down to 12-15 km depth. Beside an apparent structural complexity, fault plane solutions of background seismicity reveal a homogeneous pattern of deformation with a clear NE-SW extension.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: microseismicity ; low-angle normalfault ; seismic gap ; seismic hazard ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
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    Preliminary calibration of candidate alpha stations in the GSETT-3 network (2006)
    Details
    Publication Date: 2019-11-04
    Description: The technical concept of a future global seismic monitoring system includes 50 to 60 core stations, mostly arrays, which provide the primary detection and location capability. Due to the average station distance, these core (“alpha”) stations form a teleseismic network. Many of the proposed stations are to be newly installed and before the network can be regarded as fully operational, the stations have to be calibrated. As for traditional seismic networks, the station residuals - compared to a standard earth model - have to be determined. The standard earth model is defined in terms of travel-time tables and amplitude-distance curves. After recording a representative set of events, station residuals with respect to travel-time and magnitude can be calculated. In case of arrays, the determination of mislocation vectors (azimuth and slowness residuaIs) are of ulmost importance if array slowness vectors are used as starting solutions in a location procedure. Finally, in a monitoring context it is very important to estimate the station sensitivity for varying background noise conditíons and - in case of arrays - to know the frequency dependent improvement by beamforming. This paper uses the newly installed high-frequency GERESS array in Germany to demonstrate the calibration procedure.
    Description: JCR Journal
    Description: open
    Keywords: global seismic networks ; station calibration ; array location ; magnitude residual ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    Automatic processing of seismic events recorded on a mini-array Signal analysis combined with neural networks (2006)
    Details
    Publication Date: 2019-11-04
    Description: We present a new method for automatic processing of mini-array records of regional events. It is based on a comprehensive analysis of the cross-correlation functions. This leads to a set of time-delays used to compute the azimuth and velocity of the travelling wave only in case of consisteney of the time-delay set. The second step takes into account the time-frequency representations of these wave parameters to identify each regional wave using a neural network. The resulting standard error on azimuth is 3° and the relative error on distance is less than 20%.
    Description: JCR Journal
    Description: open
    Keywords: neural networks ; mini-array ; automatic seismic processing ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques ; 05. General::05.06. Methods::05.06.99. General or miscellaneous
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    Application of seismogram synthesis to the study of earthquake source from strong motion records (2006)
    Details
    Publication Date: 2019-11-04
    Description: We present the results of an analysis of the Michoacan and Landers earthquakes to constrain the kinematic description of the rupture process. The example of the Michoacan earthquake shows that a crack type model is better a dislocation model to describe the displacement in the vicinity of the fault. We also show that this in contradiction with the fact that the faulting appears to be a complex process. We attribute this complexity to instabilities in crack growth. The June 28, Landers earthquake offers an exceptional opportunity to apply a new inversion technique to a major strike slip event. We model the rupture evolution including local differences in slip durations and variations in rupture velocity. The slip distribution shows that this event consists of a series of regions of high slip (sub-events) separated by regions of relative low slip. Our inversion favors the hypothesis that the duration of the slip at each point is of the order of the duration of the rupture of each sub-event and is consistent with a crack type process occurring during each sub-event. For such a large earthquake, the slip duration is however smaller than the total rupture duration.
    Description: JCR Journal
    Description: open
    Keywords: strong motion ; earthquake source ; rise-time ; inversion ; Landers ; Michoacan ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    Inferences on the source mechanisms of the 1930 Irpinia (Southern Italy) earthquake from simulations of the kinematic rupture process (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: We examine here a number of parameters that define the source of the earthquake that occurred on 23rd July 1930 in Southern Italy (in the Irpinia region). Starting from the source models proposed in different studies, we have simulated the acceleration field for each hypothesized model, and compared it with the macroseismic data. We then used the hybrid stochastic-deterministic technique proposed by Zollo et al. (1997) for the simulation of the ground motion associated with the rupture of an extended fault. The accelerations simulated for several sites were associated with the intensities using the empirical relationship proposed by Trifunac and Brady (1975), before being compared with the available data from the macroseismic catalogue. A good reproduction of the macroseismic field is provided by a normal fault striking in Apenninic direction (approximately NW-SE) and dipping 55° toward the SW.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: 1930 Irpinia earthquake ; ground motion simulation ; kinematic source model ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    An improved seismicity picture of the Southern Tyrrhenian area by the use of OBS and land-based networks: the TYDE experiment (2006)
    Details
    Publication Date: 2019-02-01
    Description: The problem of large location uncertainties for seismicity occurring in the Southern Tyrrhenian Sea have been partially exceeded during the implementation of the long-term scientific mission of the TYrrhenian Deep sea Experiment (TYDE), which allowed the installation of 14 wide-band Ocean Bottom Seismometers (OBS) and Hydrophones (OBH) in the period December 2000 – May 2001 on the sea-bottom floor around the Aeolian and Ustica Islands. Local events recorded at landstations have been observed also on the seismograms of the Ocean Bottom Seismic Network (OBSN). Moreover, some hundreds of low magnitude events, undetected from the land networks, have been recorded. We combined the readings of body wave arrival times from OBS-OBH with those from landstations to localise seismic events. We focused our study on three clusters of events representative of the seismic activity of the area: (i) “deep” events, (ii) Ustica (iii) NE-Sicily. The analysis of the integrated data set of the seismicity off-shore and on-shore, obtained from the combined land-OBS seismic network (Ustica sequence and Deep events), has improved locations in terms of RMS residuals, azimuthal gap, epicentral and hypocentral errors. Moreover, further classes of events have been analysed: the first one includes some local events that could be located only by integrating single trigger readings from the few available land-stations with the OBSN-data; the second one comprises local events that have been detected only by the OBS-OBH stations. In particular, the last cluster underlines the importance of an OBSN in the Tyrrhenian deep basin to reveal its unknown intense micro-seismicity, permitting to better understand both the tectonic and geodynamic picture of the area.
    Description: Published
    Description: 3A. Geofisica marina
    Description: JCR Journal
    Description: open
    Keywords: Ocean bottom seismograph ; integrated seismic networks ; southern Tyrrhenian Sea ; Aeolian islands ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
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    A microseismic study in a low seismicityarea: the 2001 site-response experimentin the Città di Castello Basin (Italy) (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: A site response experiment was performed in the basin of Città di Castello (a small town in Central Italy) in May 2001. This study is part of a project on the evaluation of seismic hazard in seismogenic areas funded by the Gruppo Nazionale Difesa dai Terremoti (GNDT). The experiment consisted of a dense fixed transect configuration with most of the stations recording in continuous mode, and several ambient noise measurements both in single station and in array configuration spread over the investigated area. The dense transect was composed of 26 seismic stations in a crosswise configuration with a maximum inter-station distance of 250 m. The stations were deployed in the southern part of the basin, from the eastern bedrock outcrop to the western edge, across the town. About 70 earthquakes were recorded during 10 days of deployment, generally low magnitude or regional events. We located 23 earthquakes and 17 of them were located using the waveform similarity approach at 4 stations outside the target area. These 4 stations were part of a dense temporary seismic network involved in a previous experiment of the same project, aimed at performing a high-resolution picture of the local seismicity. Delay analysis on the recorded waveforms allowed us to infer the basin geometry at depth and estimate the S-wave velocity of sediments. Moreover, we evaluated relative site response along the E-W transect by performing a standard spectral ratio. Amplification factors up to 9 are found inside the basin; at frequencies above 5 Hz stations closer to the edges show higher amplification, whereas stations located in the middle of the basin, where the alluvial sediments are thicker (CD11-CD14), show higher amplification below 5 Hz. We considered the average amplification in two frequency bands (1-5 Hz and 5-10 Hz), representative of the resonance frequency for 2-3 storey buildings and 1 storey houses,respectively. Our results suggest that the potential hazard for 2-3 storey buildings is higher in the center of the basin (amplification factor up to 6), and for 1 storey houses is higher at the edges (amplification factor up to 5).
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: dense seismic array ; weak motion ; ambient noise ; basin geometry ; urban area ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
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    Nonparametric analysis of the time structure of seismicity in a geographic region (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: As an alternative to traditional parametric approaches, we suggest nonparametric methods for analyzing temporal data on earthquake occurrences. In particular, the kernel method for estimating the hazard function and the intensity function are presented. One novelty of our approaches is that we take into account the possible dependence of the data to estimate the distribution of time intervals between earthquakes, which has not been considered in most statistics studies on seismicity. Kernel estimation of hazard function has been used to study the occurrence process of cluster centers (main shocks). Kernel intensity estimation, on the other hand, has helped to describe the occurrence process of cluster members (aftershocks). Similar studies in two geographic areas of Spain (Granada and Galicia) have been carried out to illustrate the estimation methods suggested.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: nonparametric estimation ; hazard function ; intensity function ; dependent data ; clustering ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk
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    A preliminary studyof the site-dependence of the multifractalfeatures of geoelectric measurements (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: Multifractal analysis was performed to characterize the fluctuations in dynamics of the hourly time variability of self-potential signals measured from January 2001 to September 2002 by three stations installed in the Basilicata region (Southern Italy). Two stations (Giuliano and Tito) are located in a seismic area, and one (Laterza) in an aseismic area. Multifractal formalism leads to the identification of a set of parameters derived from the shape of the multifractal spectrum (the maximum a0, the asymmetry B and the width W) and measuring the «complexity» of the signals. Furthermore, the multifractal parameters seem to discriminate self-potential signals measured in seismic areas from those recorded in aseismic areas.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: self-potential signals ; multifractal formalism ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
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    Northern Sicily, September 6, 2002earthquake: investigation on peculiarmacroseismic effects (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: The Northern Sicily, September 6, 2002 earthquake (Ml = 5.6, MW = 5.9) is investigated under macroseismic aspect: peculiar effects are collected besides standard effects normally used to define Mercalli-Cancani-Sieberg (MCS) intensity. They include sound heard during the quake, fear felt and a simple qualitative description of ground movement felt. Spatial coverage of such information is dense enough to be statistically processed, to give an interpolated, smoothed field for each data type. Sound heard is compared with theoretical sound field produced considering source geometry and transmission of waves to air, it also confirms the Southern Sicily amplification disclosed by macroseismic intensity values. Fear felt is also in agreement with macroseismic intensity field while type of ground motion is a partly independent aspect.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: macroseismic intensity ; earthquakesound ; macroseismic effects ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    Association of Total Electron Content (TEC) and foF2 variations with earthquake events at the anomaly crest region (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: The paper attempts to identify ionospheric parameters in association with earthquake at anomaly crest station through VHF Radio Beacon data and ground based ionosonde measurements while the Total Electron Content(TEC) parameters from RB observations are based mainly on data taken over Guwahati (26.2°N, 91.75° E), foF2 data used in the analysis were collected at Ahmadabad (23.01°N, 72.36°E). The paper describes methods and techniques adopted to examine modifications on these parameters if any, due to earthquake preparatory processes at equatorial anomaly crest stations. The mechanism of inducement of density changes in the ionosphere is sought through the generation of strong fountain effect possibly by the development of electric field during the earthquake preparatory process.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: earthquake ; TEC ; foF2 ; anomaly ; 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques ; 04. Solid Earth::04.02. Exploration geophysics::04.02.06. Seismic methods ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
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    Deep-sea borehole seismological observatories in the western Pacific: temporal variation of seismic noise level and event detection (2006)
    Details
    Publication Date: 2019-11-04
    Description: Seismological networks provide critical data for better understanding the dynamics of the Earth; however, a great limitation on existing networks is the uneven distribution of stations. In order to achieve a more uniform distribution of seismic stations, observatories must be constructed in marine areas. The best configuration for oceanic seismic observatories is thought to be placement of seismometers in deep boreholes. Two deep-sea borehole seismological observatories (WP-1 and WP-2) were constructed in the western Pacific and form the initial installations of a 1000 km span network. At present, seismic records of more than 400 total days were retrieved from both the WP-1 and WP-2. Long-term variations in broadband seismic noise spectra (3mHz - 10 Hz) in the western Pacific were revealed from these records, and the data showed that ambient seismic noise levels in borehole observatories are comparable to those of the quietest land seismic stations. In addition, there is little temporal variation of noise levels in periods greater than 10 seconds. Due to this low seismic noise environment, many teleseismic events with magnitudes greater than 5 were recorded. It is confirmed that seismic observation in deep-sea borehole gives the best environment for earthquake observation in marine areas.
    Description: JCR Journal
    Description: open
    Keywords: deep-sea borehole observatory ; broadband seismometer ; seismic noise level ; long-term observation ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
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    The monterey bay broadband ocean bottom seismic observatory (2006)
    Details
    Publication Date: 2019-11-04
    Description: We report on the installation of a long-term buried ocean-floor broadband seismic station (MOBB) in Monterey Bay, California (USA), 40km off-shore, at a water depth of 1000 m. The station was installed in April 2002 using a ship and ROV, in a collaborative effort between the Monterey Bay Aquarium Research Institute (MBARI) and the Berkeley Seismological Laboratory (BSL). The station is located on the western side of the San Gregorio Fault, a major fault in the San Andreas plate boundary fault system. In addition to a 3-component CMG-1T seismometer package, the station comprises a current meter and Differential Pressure Gauge, both sampled at high-enough frequency (1 Hz) to allow the study of relations between background noise on the seismometers and ocean waves and currents. The proximity of several land-based broadband seismic stations of the Berkeley Digital Seismic Network allows insightful comparisons of land/ocean background seismic noise at periods relevant to regional and teleseismic studies. The station is currently autonomous. Recording and battery packages are exchanged every 3 months during scheduled one day dives. Ultimately, this station will be linked to shore using continuous telemetry (cable and/or buoy) and will contribute to the earthquake notification system in Northern California. We present examples of earthquake and noise data recorded during the first 6 months of operation of MOBB. Lessons learned from these and continued recordings will help understand the nature and character of background noise in regional off-shore environments and provide a reference for the installation of future off-shore temporary and permanent broadband seismic stations.
    Description: JCR Journal
    Description: open
    Keywords: seismic station ; San Gregorio Fault ; earthquake ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
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    Source characteristics of moderate size events using empirical Green funclions: an application to some Guerrero (Mexico) subduction zone earthquakes (2006)
    Details
    Publication Date: 2019-11-04
    Description: The records of an aftershock (M ~ 4) of a moderate size event (M = 5.9) which occurred along the subduction zone of Guerrero (Mexico), are used as empirical Green functions (EGF) to determine the source characteristics of the mainshock and of its smaller size (M = 5.5) foreshock. The data consist of accelerograms recorded by the Guerrero Accelerograph Array, a high dynamic range strong motion array. The three events appear to be located close to each other at distances much smaller than the source to receiver distances. The fault mechanism of the mainshock is computed by non-linear inversion of P polarity readings and S wave polarizations determined at two near source stations. The foreshock and aftershock fault mechanisms are similar to that of the mainshock as inferred from long period data and shear wave polarization analysis. The maximum likelihood solution is well constrained, indicating a typical shallow dipping thrust fault mechanism, with the P-axis approximately oriented in a SSW direction. The source time functions (STFs) of the mainshock and foreshock events are determined using a new method of deconvolution of the EGF records at three strong motion sites. In this method the STF of the large event is approximated by a superposition of pseudo triangular pulses whose parameters are determined by a non-linear inversion in frequency domain. The source time function of the mainshock shows the presence of two separate pulses, which can be related to multiple rupture episodes. The relative location of mainshock sub-events is done by using plots of isochrones computed from measurementes of the time delay between pulses on the STF records at each station. The first sub-event is located no more than 2.5-3 km away from the other along the fault strike. The STF retrieved from foreshock records shows single pulse waveforms. The computed STFs are used to estimate seismic moments, source radii and stress release of the events assuming a circular fault model and constant rupture velocity. The final rupture model for the mainshock indicates the successive breaking of two nearby large slip patches having sizes of the order of a few kilometers and with the rupture propagating at an average speed close to the shear wave velocity.
    Description: JCR Journal
    Description: open
    Keywords: empirical Green function ; source time function ; pseudo-triangular pulse ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
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    Autoregressive models as a tool to discriminate chaos from randomness in geoelectrical time series: an application to earthquake prediction (2006)
    Details
    Publication Date: 2019-11-04
    Description: The time dynamics of geoelectrical precursory time series has been investigated and a method to discriminate chaotic behaviour in geoelectrical precursory time series is proposed. It allows us to detect low-dimensional chaos when the only information about the time series comes from the time series themselves. The short-term predictability of these time series is evaluated using two possible forecasting approaches: global autoregressive approximation and local autoregressive approximation. The first views the data as a realization of a linear stochastic process, whereas the second considers the data points as a realization of a deterministic process, supposedly non-linear. The comparison of the predictive skill of the two techniques is a test to discriminate between low-dimensional chaos and random dynamics. The analyzed time series are geoelectrical measurements recorded by an automatic station located in Tito (Southern Italy) in one of the most seismic areas of the Mediterranean region. Our findings are that the global (linear) approach is superior to the local one and the physical system governing the phenomena of electrical nature is characterized by a large number of degrees of freedom. Power spectra of the filtered time series follow a P(f) = F-a scaling law: they exhibit the typical behaviour of a broad class of fractal stochastic processes and they are a signature of the self-organized systems.
    Description: JCR Journal
    Description: open
    Keywords: self-potential time series ; chaos ; dynamical system ; earthquake prediction ; 04. Solid Earth::04.06. Seismology::04.06.02. Earthquake interactions and probability ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
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    Seismomagnetic models for earthquakes in the eastern part of Izu Peninsula, Central Japan (2006)
    Details
    Publication Date: 2019-11-04
    Description: Seismomagnetic changes accompanied by four damaging earthquakes are explained by the piezomagnetic effect observed in the eastern part of Izu Peninsula, Central Japan. Most of the data were obtained by repeat surveys. Although these data suffered electric railway noise, significant magnetic changes were detected at points close to earthquake faults. Coseismic changes can be well interpreted by piezomagnetic models in the case of the 1978 Near Izu-Oshima (M 7.0) and the 1980 East Off Izu Peninsula (M 6.7) earthquakes. A large total intensity change up to 5 nT was observed at a survey point almost above the epicenter of the 1976 Kawazu (M 5.4) earthquake. This change is not explained by a single fault model; a 2-segment fault is suggested. Remarkable precursory and coseismic changes in the total force intensity were observed at KWZ station along with the 1978 Higashi-Izu (M 4.9) earthquake. KWZ station is located very close to a buried subsidiary fault of the M 7.0 Near Izu-Oshima earthquake, which moved aseismically at the time of the M 7.0 quake. The precursory magnetic change to the M 4.9 quake is ascribed to aseismic faulting of this buried fault, while the coseismic rebound to enlargement of the slipping surface at the time of M 4.9 quake. This implies that we observed the formation process of the earthquake nucleation zone via the magnetic field.
    Description: JCR Journal
    Description: open
    Keywords: seismomagnetic effect ; piezomagnetic effect ; Izu Peninsula ; magnetic precursor to earthquake ; preseismic slip ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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    Application of numerical simulations for a tentative seismic microzonation of the city of Rome (2006)
    Details
    Publication Date: 2019-11-04
    Description: A hybrid technique, based on mode summation and finite differences, was used to silnulate the ground motion induced in the city of Rome by possible earthquakes occurring in the main seisrnogenetic areas surrounding the city: the Central Apennines and the Alban Hills. The results of the numerical simulations are used for a seismic inicrozonation in the city of Rome, which can be used for the retrofitting of buildings of special social and cultural value. On the basis of our analysis Rome can be divided into six main zones: (1) the edges and (2) the central part of the alluvial basin of the River Tiber; (3) the edges and (4) the central part of the Paleotiber basin; the areas outside the large basins of the Tiber and Paleotiber, where we distinguish between (5) areas without, and (6) areas with a layer of volcanic rocks close to the surface. The strongest amplification effects have to be expected at the edges of the Tiber basin, with maximum spectral amplification of the order of 5 to 6, and strong arnplifications occur inside the entire alluvial basin of the Tiber. The presence of a near-surface layer of rigid material is not sufficient to classify a location as a 〈〈hard-rock site〉〉 when the rigid material covers a sedimentary complex. The reason is that the underlying sedimentary complex causes amplifications at the surface due to resonance effects. This phenomenon can be observed in the Paleotiber basin, where spectral amplifications in the frequency range 0.4-1.0 Hz reach values of the order of 3 to 4.
    Description: JCR Journal
    Description: open
    Keywords: Rome ; wave-propagation modelling ; seismic strong ground motion ; seismic microzonation ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk
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    Evaluation of sixteen years of INGV seismic Bulletins (2006)
    Details
    Publication Date: 2019-11-04
    Description: In this work we analyze earthquake parameters published in the Seismic Bulletin of the Istituto Nazionale di Geofisica e Vulcanologia (INGV) The analysis and the interpretation of the digital signals, done by specialized employees daily, produce most of the seismological information that comprises INGV’s earthquake bulletins. After a brief introduction on the criteria we use to obtain seismic parameters, this paper will review the processing procedures employed over a period of sixteen years from 1988 to September 2003. This study also addresses the issue of the comparison between Magnitude calculated on signal duration (Md) and on amplitude (ML) and the lack of a correct calibration between them . A completeness analysis of the whole bulletin performed using both the Stepp and the Habermann techniques shows the importance of considering changes in the seismicity rate and in the geometry of the seismological network. To conclude this excursus, we calculated the errors of hypocentral locations and the detection capacity of individual seismic stations. This final step stresses the increasing improvement of the INGV seismic network over the past 16 years.
    Description: JCR Journal
    Description: open
    Keywords: earthquake parameters ; errors of hypocentral locations ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    Parameters estimation of intensity decay relationships (2006)
    Details
    Publication Date: 2019-11-04
    Description: This paper presents a methodology that analyses a set of observed intensities and estimates the parameters of an adopted attenuation law directly using the data points. A procedure was developed to define and evaluate the equivalent radii Di of the isoseismal lines. From these data it is possible to derive the parameters of the attenuation law. Moreover a validation procedure was developed to measure the capability of intensity decay relationships to reproduce the observed intensities. A case study of 55 earthquakes, divided into 9 subsets, of similar-attenuation zones, was analysed, using, as attenuation law, the one proposed by Grandori (1987, l991) to estimate either the parameters for each single earthquake or the parameters of an average intensity decay relationship for the similar-attenuation zones. The calculated intensity decay relationships result in 60- 70% of correctly reproduced points for most intensity data maps analysed. Analysing the similar-attenuation zones and different earthquakes simultaneously, the parameters of attenuation laws obtain results with a lower percentage of correctly reproduced points. The proposed methodology seems to be effective and suitable to reach practical results in parameters estimation of intensity decay relationships.
    Description: JCR Journal
    Description: open
    Keywords: intensity data-points ; equivalent radius ; intensity decay relationships ; validation criteria ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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    Attenuating intensities (2006)
    Details
    Publication Date: 2019-11-04
    Description: The study presents a methodology in which fractile distances for a given macroseismic intensity are used as a point measure on which to do attenuation characterization. The use of statistically derived distances expected not to be exceeded at a given probability avoids ambiguous definition of isoseismal radii, and consequent mis- interpretation of attenuation parameters with a physical content. The utility and definiteness of such a fractile distance is evident when treating many earthquakes, of different magnitudes and for which the macroseismic data-sets are of different sizes. The methodology is applied to 55 Italian earthquakes of the last four centuries, with epicentral intensity ranging from VII to XI MCS. Propagation properties in volcanic districts are peculiar, with a rapid decay of observed intensity from the epicentre. The attenuation properties of the other crustal en- vironments are not clcarly correlated with the geodynamic domain; the earthquakes show a mean behaviour that appears to depend on relatively homogeneous conditions of propagation. Source depth, tectonic style and finiteness of the source are not addressed because only macroseismic surveying had been applied to most of the earthquakes, and they cannot be linked to surficial fault ruptures. The study is intended to provide mean attenuations that can be used in probabilistic seismic hazard studies; the variabiljty of individual earthquake attenuations for a region introduces the need to use different parameters in future deterministic earthquake scenarios.
    Description: JCR Journal
    Description: open
    Keywords: macroseismic intensity ; attenuation relationship ; seismic hazard ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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    Long-period modelling of MEDNET waveforms for the December 13, 1990 Eastern Sicily earthquake (2006)
    Details
    Publication Date: 2019-11-04
    Description: The availability of broad-band digital data allow "the analysis" of the seismic signal in the low-noise frequency band for structural and seismic source studies, We model complete seismograms -surface and body waves - for the December 13, 1 990, Eastern Sicily earthquake, recorded at regional distances on the MEDNET stations AQU, BNI and KEG, The inversion for the moment tensor is carried out following two approaches: a) a model-independent stralegy to fit complete seismograms in the 100-130 s period range; b) the calibration of phase velocity curves along each path to fit surface waves in the 40-100 s range, Both methodologies yield stable and consistent results: the 1990 Eastern Sicily earthquake had a seismic moment of M/o = 37 x 1024 dyne.cm, corresponding lo magnitude values of mb = 5,5, Ms = 5,7, Mw = ML = 5.8. In a second stage, synthetic seismograms arc generated by full reflectivity in the 5-50 s period range, with a new code based on the "minors" integration. By modelling surface waves in the 30-50 s range and body waves to 5 s periods, we derive average velocity models for the Central and Eastern Mediterranean, and constrain the hypocenter of the 1990 Eastern Sicily earthquake to be in the 13-17 km depth range.
    Description: JCR Journal
    Description: open
    Keywords: Seismic moment ; inversion techniques ; very-broand-band waveforms ; regional earthquake ; Eastern Sicily ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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    An algorithm for doble difference joint hypocenter determination: application to the 2002 Molise (Central Italy) earthquake sequence (2006)
    Details
    Publication Date: 2019-11-04
    Description: We have developed an original computer code for double difference hypocenter determination including an independent routine for the cross-correlation estimate of the time difference between two waveform segments, relative to different events recorded by the same stations. This computer code has been tested relocating a set of 26 events recorded by the seismic stations of the telemetered Italian national network operated by the INGV. The hypocentral solutions so obtained are characterized by standard deviations typically of the order of magnitude of 50 m, in comparison with the errors of a few kilometers characterizing the performance of the INGV bulletins. The proximity of hypocenters in several groups of events closely separated in time shows that our relocations are the result of an accurate analysis, rather than that of random errors. The method developed in this study is suitable for rapid and accurate hypocentral determination carried out by a permanent sparsely distributed network of stations, even before that mobile equipment installed in the area affected by new seismic activity allows higher resolution locations.
    Description: JCR Journal
    Description: open
    Keywords: Aftershocks ; Foreshocks ; Joint Hypocenter Determination ; Double Difference ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques ; 05. General::05.04. Instrumentation and techniques of general interest::05.04.99. General or miscellaneous ; 05. General::05.06. Methods::05.06.99. General or miscellaneous
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    A study of local site effects in Benevento(Southern Italy) by the analysis of seismic records of explosions (2006)
    Details
    Publication Date: 2019-11-04
    Description: In this paper we evalllate the seismic amplification effects in the town of Benevento llsing records of an explo- sion of 500 kg fired at abollt 7 km. Seismic records were obtained at 43 selected sites in the city by digital three-component stations. A data selection performed on the signal-to-noise ratio reduced the available data to 26 stations. We used the spectral ratio techniques to evaluate the amplification effects of each recording site compared both to the average spectrum calculated over 26 stations and to a reference seismic station. The shapes of the spectral ratios were classified according to the geological characteristics of the site. A characteristic shape of the spectral ratio was observed to be related to the specific structure of the subsoil. In particular, the sites on basin sediments (Lagonegro Unit) and Middle Pleistocene conglomerates failed to show amplification effects; the sites on thick alluvial deposits showed amplification in the 5-9 Hz range; finally, sites on alluvial-lacustrine deposits amplified the seismic signal at frequencies depending on the characteristics and the thickness of the deposit. In addition, damage distribution caused by the 1688 earthquake in Benevento was related to the thickness of the surface layers in the ancient built-up area of the town. The study of the spectral ra- tios showed that these deposits amplify ground motion at frequencies between 9 and 12 Hz, i.e. frequencies close to the natural period of the most widespread buildings at that time in Benevento. Geological and seismic data were jointly used to carry out a zonation of the urban area of Benevento on the basis of homogeneous seismic responses. The validity of this analysis is limited to the main frequency band and amplitude of ground motion produced by the explosions.
    Description: JCR Journal
    Description: open
    Keywords: site effects ; spectral ratio ; Southern Apennines ; Benevento ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    Study of blind thrust faults underlying Tokyo and Osaka urban areas using a combination of high-resolution seismic reflection profiling and continuous coring (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: We acquired high-resolution seismic reflection profiles and continuously cored boreholes to evaluate active flexures produced by major blind thrust fault systems within two densely populated Neogene-Quaternary sedimentary basins in Japan: the Fukaya Fault System near Tokyo in the Kanto Basin and the Uemachi Fault System in the Osaka Basin. The high-resolution seismic reflection survey made clear the length, geometry and growth history of fault-related folds, or flexures formed above the two blind thrusts. Continuously cored boreholes linked with high-resolution seismic profiles enabled us to estimate the uplift rate as defined by shallow stratigraphic horizons and constrain the age of the most recent growth of the flexures during earthquakes on the Fukaya and Uemachi fault systems. Even with the high quality of the data we collected, it is still not possible to exactly constrain the age of the most recent blind thrust earthquake recorded by flexure of these fault-related folds. Data presented in this paper form the basis for future efforts aimed at mechanical and kinematic models for fault growth to evaluate the activity of blind thrusts underlying urban areas.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: blind thrust ; fault-related fold ; flexure ; high-resolution seismic reflection profiling ; continuou scoring ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    Normal-fault stress and displacement through finite-element analysis (2006)
    Details
    Publication Date: 2019-11-04
    Description: We compute displacement and stress due to a normal fault by means of two-dimensional plane-strain finite-element analysis. To do so, we apply a system of forces to the fault nodes and develop an iterative algorithm serving to determine the force magnitudes for any slip distribution. As a sample case, we compute the force magnitudes assuming uniform slip on a 10-km two-dimensional normal fault. The numerical model generates displacement and stress fields that compare well with the analytical solution. In fact, we found little difference in displacements (〈5%), displacement orientation (〈15°), and stress components (〈35%, half of which due to slip tolerance). We analyze such misfit, and discuss how the error propagates from displacement to stress. Our scheme provides a convenient way to use the finite-elements direct method in a trial-and-error procedure to reproduce any smooth slip distribution.
    Description: JCR Journal
    Description: open
    Keywords: algorithms ; earthquakes ; faults ; theoretical studies ; numerical models ; analytical models ; displacements ; stress ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques ; 05. General::05.01. Computational geophysics::05.01.05. Algorithms and implementation
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    Pattern of seismicity in the Lucanian Apennines and foredeep (Southern Italy) from recording by SAPTEX temporary array (2006)
    Details
    Publication Date: 2019-11-04
    Description: The deployment of a temporary seismic network in Southern Italy during 2001-2004 (the SAPTEX array, Southern APennine Tomography EXperiment) allowed us to relocate the hypocenters of Southern Apennines earthquakes with low uncertainty among the location parameters. The best array distribution of the SAPTEX network for the analysis of seismicity in the Lucanian Apennines and foredeep was reached in the first two years of recording. The SAPTEX data were merged with those of the Italian National Seismic Network (RSNC) operated by the Istituto Nazionale di Geofisica e Vulcanologia (INGV). For the hypocenters computation of events in the upper Agri Valley we also included P- and S- waves arrivals from the local Eni-Agip network. The seismicity for the Lucanian Apennines and foredeep in the analyzed period has magnitudes ranging from 2.0 to 4.1. A major finding is the identification of two different crustal domains: the westernmost characterizing the chain, mostly with shallow earthquakes (within about 20 km of depth), and the easternmost one belonging to the outer margin of the chain and to the foredeep, with deeper seismicity (mostly between 20-40 km of depth). Thirty fault-plane solutions were computed and used for stress inversion; most of them are related to earthquakes within the chain sector and indicate a generalized NE-SW extension. Moreover, the dense network allowed us to improve the location of events relative to two low magnitude sequences which occurred in the study period.
    Description: JCR Journal
    Description: open
    Keywords: seismicity ; seismic network ; motectonics ; Lucanian Apennines ; Lucanian foredeep ; Southern Italy ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques ; 05. General::05.02. Data dissemination::05.02.02. Seismological data ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    Earthquake, GIS and multimedia. The 1883 Casamicciola earthquake (2006)
    Details
    Publication Date: 2019-11-04
    Description: A series of multimedia monographs concerning the main seismic events that have affected the Italian territory are in the process of being produced for the Documental Integrated Multimedia Project (DIMP) started by the Italian National Seismic Survey (NSS). The purpose of the project is to reconstruct the historical record of earthquakes and promote an earthquake public education. Producing the monographs. developed in ARC INFO and working in UNIX. involved designing a special filing and management methodology to integrate heterogeneous information (images, papers, cartographies, etc.). This paper describes the possibilities of a GIS (Geographic Information System) in the filing and management of documental information. As an example we present the first monograph on the 1883 Casamicciola earthquake. on the island of Ischia (Campania, Italy). This earthquake is particularly interesting for the following reasons: I) historical-cultural context (first destructive seismic event after the unification of Italy); 2) its features (volcanic earthquake); 3) the socioeconomic consequences caused at such an important seaside resort.
    Description: JCR Journal
    Description: open
    Keywords: Earthquake ; GIS, Multimedia ; documentation, education ; Casamicciola (Italy) ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    Macroseismic intensity evaluation with the 〈〈Fuzzy Sets Logic〉〉 (2006)
    Details
    Publication Date: 2019-11-04
    Description: The use of a macroseismic scale often requires subjective choices and judgments which may produce inhomogeneities and biases in the resulting intensities. To get over this problem it would be necessary to formalize the decision process leading to the estimation of the macroseismic intensity but, on historical records, this is often hindered by the poorness and incompleteness of the aLailable information and by the intrinsical ambiguity of the common language. Moreover. all the intensity scales have always been created and updated to be used 〈〈in the field. on contemporary earthquakes and then it may happen tkdt even detailed historical descriptions often do not correspond to the descriptive frameworks of any grade. I11 order to face these problems. we propose in this work a computer method for the evaluation of the macroseismic intensity which makes use of the 〈〈Fuzzy Sets Logic〉〉T. his approach reproduces the taslts performed by the hurnan brain which. taking advantage of the tolerance of imprecision. is able to handle with information bearing only an approximate relation to the data. This allows to understand and make explicit some passes of the evaluation process that are unconsciously followed by the macroseismic exper
    Description: JCR Journal
    Description: open
    Keywords: macroseismic intensity ; fuzzy sets ; MCS scale ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    Seismic damage and destructive potential of seismic events (2006)
    Details
    Publication Date: 2019-11-04
    Description: This paper has been written within a research framework investigating the destructive potential of seismic events. The elastic response spectra seem insufficient to explain the behaviour of structures subject to large earthquakes in which they experience extensive plastic deformations. Recent works emphasise that there were many difficulties in the definition of a single pararneter linked to the destl-uctive potential of an earthquake. In this work a study on the effect of frequency content on structural damage has been carried out. The behaviour of two different elastoplastic oscillators has been analysed, considering several artificial earthquakes. The results obtained suggest a method for evaluating the destructive seismic potential of an earthquake through the response spectra ad the frequency content of the signal. and through the mechai~ical characteristics of the structures within the analysed area.
    Description: JCR Journal
    Description: open
    Keywords: seismic desctructive potential ; frequency content ; elasto-plastic oscillator ; response spectra ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    Underground earth strain and seismic radiation measurements with a laser interferometer and a dense small-aperture seismic array (2006)
    Details
    Publication Date: 2019-11-04
    Description: This paper describes two geophysical instruments, installed in the underground physics laboratories of Gran Sasso (LNGS-INFN), located in the seismic zone of the Central Apennines, Italy. These instruments monitor strain and seismic radiation with very high sensitivity: one is a 90 m-long laser interferometer, sensitivity 3 x 10-12, frequency response 10-7-10-2 Hz, and has been operating since 1994. The other is a small-aperture seismic array composed of 21 three-component short period (Mark L4C-3D) and 3 broadband (Guralp CMG-3ESP) seismometers. This dense array will be in operation at the beginning of 1998.
    Description: JCR Journal
    Description: open
    Keywords: strain ; seismic array ; seismometry ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
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    Intensity assessment from documentary data. Criteria and procedures in the daily practice of seismologists (2006)
    Details
    Publication Date: 2019-11-04
    Description: A major problem in assessing macroseismic intensity from historical records is the lack of a standardized procedure for processing documentary sources and supplying unequivocal intensity estimates. In fact, most macroseismic, scales do not include detailed descriptions of procedures for intensity assessment and many divergent interpretations of intensity values arc obtained by different operators. In order to disclose these problems an experiment was made in Italy in 1994, in the framework of GNDT "Seismicity" Working Group. A set of selected documents concerning origil1al descriptions of effects produced by earthquakes which had occurred in Italy from 15th to 20th century, was supplied to a number of independent researchers. Each of them was invited to assess on this basis the intensity values and to explain his intellectual path by describing it in detail. This documentation was finally collected and, during a meeting devoted to this topic, the researchers involved were invited to discuss their personal experiences. The discussion indicated that the discrepancies between the estimate obtained by the different authors from the same documentary source are, in many cases, greater than 1 degree. This implies that the effect of personal choices may play an important role in intensity assessment and makes intensity estimates performed by the different authors less comparable. At present no definitive conclusions about these problems can be drawn but the topics focused during the meeting may represent a useful basis for a wider discussion to define a standardized procedure for thc assessment of intensity from documentary data.
    Description: JCR Journal
    Description: open
    Keywords: Earthquake ; macroseismic scales ; historical records ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    Lithospheric structure models applied for locating the Romanian seismic events (2006)
    Details
    Publication Date: 2019-11-04
    Description: The paper presents our attempts made for improving the locations obtained for local seismic events, using refined lithospheric structure models. The location program (based on Geiger method) supposes a known model. The program is run for some seismic sequences which occurred in different regions, on the Romanian territory, using for each of the sequences three velocity models: 1) 7 layers of constant velocity of seismic waves, as an average structure of the lithosphere for the whole territory; 2) site dependent structure (below each station), based on geophysical and geological information on the crust; 3) curves deseribing the dependence of propagation velocities with depth in the lithosphere, characterizing the 7 structural units delineated on the Romanian territory. The results obtained using the different velocity models are compared. Station corrections are computed for each data set. Finally, the locations determined for some quarry blasts are compared with the real ones.
    Description: JCR Journal
    Description: open
    Keywords: location ; velocity models ; seismic sequences ; quarry blasts ; Romania ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
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    Ecological and fisheries development of Lake Manzalah (Egypt): hydrography and chemistry of Lake Manzalah (2006)
    Alexandria: National Institute of Oceanography and Fisheries
    Details
    Publication Date: 2021-05-19
    Description: This journal is published by the NIOF, Egypt
    Description: Lake Manzalah; the largest delta Lake in Egypt represents a dynamic system that has been undergoing continuous and pronounced changes since long times. In the last year’s this Lake faced drastic problems that retarded its environmental and fisheries development; the most serious one is the discharge of waste water. It is attempted in the present study to investigate the chemical characters of Lake Manzalah water during 2001-2002. Water temperature ranged from an average of 12.35oC in January and 29.14oC in July. Dissolved Oxygen, pH and total dissolved solids were found in ranges optimum for the living of marine and freshwater fish species. The average concentrations of nutrients lied in the following ranges: 1.24 to 4.89 μmol PO4 -3 l-1 , 5.08 to 28.73 μmol SiO4 -2 l-1 and 1.81 to 17.7 μ_mol NO3-1 l-1 The concentrations of phosphorus and nitrogen compounds were found to be relatively higher at the southern regions of the Lake near to the outlets of the drains.
    Description: NIOF
    Description: Published
    Keywords: Hydrography ; Water ; Chemistry ; Chemical composition ; Water content ; Environment ; Chemical composition ; Environments ; Water content ; Fisheries
    Repository Name: AquaDocs
    Type: Journal Contribution , Refereed , Article
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    Electromagnetic radiation related to dislocation dynamics in a seismic preparation zone (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: Electromagnetic emission is observed frequently before earthquakes as high noise level in VLF and ULF bands. We present theoretical considerations on electromagnetic radiation caused by dislocation dynamics in the preseismic micro-sources (micro-crackings) located in an earthquake preparation zone. Some of these micro-sources could be located near the ground surface and their electromagnetic signals could be accesible in some recording stations. The examples of the numerically simulated induction and radiation fields are given and one example of the observed radio-noise recording is shown.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: stress evolution ; instabilities ; charge dislocations ; electromagnetic emission ; 04. Solid Earth::04.05. Geomagnetism::04.05.03. Global and regional models ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    Background electromagnetic noisein the vicinity 1 Hz as a possible indicatorof earthquake-related anomalies (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: Measurements of space-time distributions of the background emissions in the frequency range 0.5-5 Hz and their seasonal and diurnal variations are presented. The analysis of impedance ratio determines the presence of high space harmonics in the emission spectral distribution. The absence of this emission during the winter time correlates with the absence of any precursors before local earthquakes with M ~ 6. It is shown that the knowledge of the background emission behavior and its origin are very important for precursor phenomena monitoring.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: electromagnetic emission ; temperature ; Earth surface ; impedance ; earthquake precursor ; 1 Hz frequency range ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    Procedures and toolsused in the investigationof New Zealand's historical earthquakes (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: New Zealands tectonic setting, astride an obliquely convergent tectonic boundary, means that it has experienced many large earthquakes in its 200-year written historical records. The task of identifying and studying the largest early instrumental and pre-instrumental earthquakes, as well as identifying the smaller events, is being actively pursued in order to reduce gaps in knowledge and to ensure as complete and comprehensive a catalogue as is possible. The task of quantifying historical earthquake locations and magnitudes is made difficult by several factors. These include the range of possible earthquake focal depths, and the sparse, temporally- and spatially-variable historical population distribution which affects the availability of felt intensity information, and hence, the completeness levels of the catalogue. This paper overviews the procedures and tools used in the analysis, parameterisation, and recording of historical New Zealand earthquakes, with examples from recently studied historical events. In particular, the 1855 M 8+ Wairarapa earthquake is discussed, as well as its importance for the eminent 19th century British geologist, Sir Charles Lyell, and for future global understanding of the connection between large earthquakes and sudden uplift, tilting and faulting on a regional scale.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: seismicity ; historicalearthquake ; earthquake catalogue ; 04. Solid Earth::04.06. Seismology::04.06.05. Historical seismology ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    Re-evaluation of early instrumental earthquake locations: methodology and examples (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: The difficulties of locating earthquakes in the early instrumental period are not always fully appreciated. The networks were sparse, and the instruments themselves were of low gain, often had inappropriate frequency response and recording resolution, and their timing could be unreliable and inaccurate. Additionally, there was only limited knowledge of earth structure and consequent phase identification and propagation. The primitive Zöppritz tables for P and S, with no allowance for the core, did not come into use until 1907, and remained the main model until the adoption of the Jeffreys-Bullen tables in the mid-1930s. It was not until the early 1920s that studies of Hindu Kush earthquakes revealed that earthquake foci could have significant depth. Although many early locations are creditably accurate, others can be improved by use of more modern techniques. Early earthquakes in unusual places often repay closer investigation. Many events after about 1910 are well enough recorded to be re-located by computer techniques, but earlier locations can still be improved by using more recent knowledge and simpler techniques, such as phase re-identification and graphical re-location. One technique that helps with early events is to locate events using the time of the maximum phase of surface waves, which is often well reported. Macroseismic information is also valuable in giving confirmation of earthquake positions or helping to re-assess them, including giving indications of focal depth. For many events in the early instrumental period macroseismic locations are to be preferred to the poorly-controlled instrumental ones. Macroseismic locations can also make useful trial origins for computer re-location. Even more recent events, which appear to be well located, may be grossly in error due to mis-interpretation of phases and inadequate instrumental coverage. A well converging mathematical solution does not always put the earthquake in the right place, and computer location programs may give unrealistically small estimates of error. Examples are given of improvements in locations of particular earthquakes in various parts of the world and in different time periods.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: earthquake location ; macroseismic locations ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    Accelerometric radiation simulation for the September 26, 1997 Umbria-Marche (Central Italy) main shocks (2006)
    Details
    Publication Date: 2019-11-04
    Description: We applied a hybrid stochastic-deterministic method to simulate the strong ground motion characteristics associated with the September 26, 1997 Umbria-Marche main shocks. One hundred different rupture processes on previously inferred fault planes were simulated. The maps of computed PGA (mean values from 100 simulations) show a SE alignment for the 00:33 event and a NW alignment for the 09:40 event, in accordance with the macroseismic data. Moreover, we found a good agreement between the predicted 1ó interval for the PGA values and the data recorded at several accelerometric stations. As a further test, we computed the response spectra at the station Cerreto di Spoleto and found a satisfactory agreement with the synthetic results.
    Description: JCR Journal
    Description: open
    Keywords: kinematic source model ; strong motion simulation ; Umbria-Marche main shocks ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    222 Rn study throughout different seismotectonical areas: comparison between different techniques for discrete monitoring (2006)
    Details
    Publication Date: 2019-11-04
    Description: n the frame of the geochemical monitoring of seismicity mainly aimed at deepening the relationships between active seismotectonics and fluid geochemistry, i.e. earthquake prediction, a 222 Rn study was accomplished. It is addressed to inter-calibrate in diverse tectonic settings different methods to measure radon in groundwater: Alpha Scintillation Method using Lucas Cells (ASM-LCC) and Gamma Spectrometry Method (GSM), adopting both the Charcoal Trap Method (CTM) by Active Charcoals Canisters (ACC) and the Beaker Marinelli (BM) sampling devices. The intercalibration occurred on the field as well as in the laboratory, to finally select the best-fitting to gather radon information in each situation. Three Italian areas were selected to verify radon behavior and background concentration in different seismotectonical, geo-structural and lithological settings: ancient metamorphosed rocks – quiescent faults (Eastern Alps), carbonate foreland – active faults (Gargano) and quiescent volcanic structure overlapping a carbonate basement – swarm seismic activity (Colli Albani). The high radon concentration variability and the factors affecting radon behavior in groundwater (i.e. carrier gases presence, convection along fault systems, lithology influence, etc.) strongly constrain the measurement method to be adopted. The results point out apparently that the ASM-LCC method may be useful for expeditious and quick response of groundwater radon concentration during geochemical surveys aimed at grossly detecting the presence of tectonic structures, the deepening of circulation or the peculiar geological features linked to the presence of U-Th minerals. This method is not reliable for accurate measurements, while the GSM methods showed low standard deviation (higher precision with respect ASM-LCC) and accurate radon measurements. Finally, a customized DINCE Standard Radiactive Source (DSRS) was set up, and first used for the efficient estimation of the ING available Lucas Cells. A calibration factor for each ING Lucas Cell was defined and the most critical aspects of the ASM-LCC method revised.
    Description: JCR Journal
    Description: open
    Keywords: radon in groundwater versus seismotectonics ; ASM-LCC and GSM methods ; Eastern Alps ; Gargano ; Colli Albani ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    Antipersistent dynamics in short time scale variability of self-potential signals (2006)
    Details
    Publication Date: 2019-11-04
    Description: Time scale properties of self-potential signals are investigated through the analysis of the second order structure function (variogram), a powerful tool to investigate the spatial and temporal variability of observational data. In this work we analyse two sequences of self-potential values measured by means of a geophysical monitoring array located in a seismically active area of Southern Italy. The range of scales investigated goes from a few minutes to several days. It is shown that signal fluctuations are characterised by two time scale ranges in which self-potential variability appears to follow slightly different dynamical behaviours. Results point to the presence of fractal, non stationary features expressing a long term correlation with scaling coefficients which are the clue of stabilising mechanisms. In the scale ranges in which the series show scale invariant behaviour, self-potentials evolve like fractional Brownian motions with anticorrelated increments typical of processes regulated by negative feedback mechanisms (antipersistence). On scales below about 6 h the strength of such an antipersistence appears to be slightly greater than that observed on larger time scales where the fluctuations are less efficiently stabilised.
    Description: JCR Journal
    Description: open
    Keywords: Fractal propeties ; variogram analysis ; antipersistence ; self-potential signal ; earthquake prediction ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    Reducing the subjectivity of intensity estimates: the Fuzzy Set approach (2006)
    Details
    Publication Date: 2019-11-04
    Description: We describe a method for the encoding and the computer analysis of the macroseismic effects deduced from historical sources allowing the complete formalization of the process of seismic intensity assessment. It makes use of a multi-criteria decisions-support algorithm, based on the theory of the Fuzzy Sets. Analyzing the texts of the available sources for the 1919 Mugello (M S = 6.2) and 1920 Garfagnana (M S = 6.5) earthquakes, the observed effects are classified independently of any macroseismic scale. Each sentence reported on the sources is "decomposed" into five syntactic elementary components and represented by a set of alphanumeric codes for further processing by computer codes. This retains the maximum adherence to the original sources and avoids forced interpretations and losses of information due to the need to fit each observed effect to a description of the scale. Moreover, this scheme also allows to gather equivalent effects by reassigning them the same code, and using this new classification in further processing. This procedure could even be useful to define a new macroseismic scale on the basis of a statistical analysis of different effect occurrences.
    Description: JCR Journal
    Description: open
    Keywords: macroseismic intensity ; fuzzy sets ; Mugello ; Garfagnana ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    Deriving numerical estimates from descriptive information: the computation of earthquake parameters (2006)
    Details
    Publication Date: 2019-11-04
    Description: We describe here how the origin time, the epicenter location, the epicentral intensity and the magnitude of the earthquakes included in the Catalogue of Strong Italian Earthquakes (CFTI3) have been determined from the documentary information available. As the literature lacks widely accepted formal definitions for these parameters in the case of macroseismic data, we developed ad hoc procedures that starting from generally shared qualitative statements give reasonable and stable results which can also be useful for statistical analysis. These procedures use all of the information available in the CFTI3 database as much as possible and make use of "robust" estimators in order to minimize the effects of anomalous data. The resulting parametric catalogue has been examined statistically for completeness showing that the great majority of the Italian earthquakes with moment magnitude larger that 5.5-6.0 of the last four centuries are correctly reported in CFTI3.
    Description: JCR Journal
    Description: open
    Keywords: macroseismic epicenter ; epicentral intensity ; macroseismic magnitude ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    Extreme value statistics and thermodynamics of earthquakes: aftershock sequences (2006)
    Details
    Publication Date: 2019-11-04
    Description: The Gutenberg-Richter magnitude-frequency law takes into account the minimum detectable magnitude, and treats aftershocks as if they were independent and identically distributed random events. A new magnitude-frequency relation is proposed which takes into account the magnitude of the main shock, and the degree to which aftershocks depend on the main shock makes them appear clustered. In certain cases, there can be two branches in the order-statistics of aftershock sequences: for energies below threshold, the Pareto law applies and the asymptotic distribution of magnitude is the double-exponential distribution, while energies above threshold follow a one-parameter beta distribution, whose exponent is the cluster dimension, and the asymptotic Gompertz distribution predicts a maximum magnitude. The 1957 Aleutian Islands aftershock sequence exemplifies such dual behavior. A thermodynamics of aftershocks is constructed on the analogy between the non-conservation of the number of aftershocks and that of the particle number in degenerate gases.
    Description: JCR Journal
    Description: open
    Keywords: Pareto and beta power laws ; cluster dimension ; frequency-magnitude regression laws ; order-statistics ; indipendence and clustering ; thermodynamics of aftershocks ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    Spectrogram analysis of selected tremor signals using short-time Fourier transform and continuous wavelet transform (2006)
    Details
    Publication Date: 2019-11-04
    Description: Among a variety of spectrogram methods Short-Time Fourier Transform (STFT) and Continuous Wavelet Transform (CWT) were selected to analyse transients in non-stationary tremor signals. Depending on the properties of the tremor signal a more suitable representation of the signal is gained by CWT. Three selected broadband tremor signals from the volcanos Mt. Stromboli, Mt. Semeru and Mt. Pinatubo were analyzed using both methods. The CWT can also be used to extend the definition of coherency into a time-varying coherency spectrogram. An example is given using array data from the volcano Mt. Stromboli.
    Description: JCR Journal
    Description: open
    Keywords: spectrogram ; wavelet transform ; broadband tremor ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
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    Analysis of multidimensional geophysical monitoring time series for earthquake prediction (2006)
    Details
    Publication Date: 2019-11-04
    Description: A method is presented for detection of synchronous signals in multidimensional time series data. It is based on estimation of eigenvalues of spectral matrices and canonical coherences in moving time windows and extraction of an aggregated signal (a scalar signal, which accumulates in its own variations only those spectral components which are present simultaneously in each scalar time series). It is known that an increase in the collective behavior of the components of some systems and an enlarged spatial radius of fluctuations of their parameters could be regarded as an important precursor of an oncoming catastrophe, i.e. abrupt change of the system's parameter values. From that point of view, detection of synchronous signals in various geophysical parameters, measured at points of some network, covering a given area of the Earth's crust, is of interest for identifying precursors of strong earthquakes. Some examples are presented of the use of this technique in the processing of real geophysical time series.
    Description: JCR Journal
    Description: open
    Keywords: collective behaviour ; spectral matrices ; canonical coherences ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    On the validity of the regional time and magnitude predictable model in China (2006)
    Details
    Publication Date: 2021-12-06
    Description: A simplified form of the "regional time and magnitude predictable model" gives the time interval, T, between two successive mainshocks in a region and the magnitude, Mf, of the following mainshock by the relations: logT=cMP+a; Mf=CMp+A, where Mp is the magnitude of the preceding mainshock, a, A are constants which depend on the minimum considered mainshock and on the region's tectonic loading (moment rate). The physical meaning of the model is that the larger the magnitude of the preceding main shock, Mp, the longer the time, T, will be till the occurrence of the next one and the smaller its magnitude, Mf. This means that parameters c and C are positive and negative, respectively, when the model has been found valid for a certain area. In order to examine if the above model is appropriate to describe the seismicity behavior in the area of China, a detailed inspection was carried out aiming to show if the estimated values of parameters c and C favor the model. The results show that c tends to the global value 0.33, obtained by Papazachos and Papadimitriou (1997), and that C tends to be within the range [-0.30, -0.23]. The results, which favored the model, greatly outnumber those that do not follow it, the latter being concentrated around the boundaries of the seismically active regions. It is concluded that the results, which favor the model, obviously dominate the whole territory of China.
    Description: JCR Journal
    Description: open
    Keywords: time dependent seismicity ; validation test ; China ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques ; 05. General::05.02. Data dissemination::05.02.02. Seismological data
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    Evolution. Darwin for all seasons (2006)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2006-07-22
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Szathmary, Eors -- New York, N.Y. -- Science. 2006 Jul 21;313(5785):306-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institute of Biology, Eotvos University Budapest, and Collegium Budapest (Institute for Advanced Study), 2 Szentharomsag utca, H-1014 Budapest, Hungary. szathmary@colbud.hu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/16857926" target="_blank"〉PubMed〈/a〉
    Keywords: *Biological Evolution ; Chemical Phenomena ; Chemistry ; Computational Biology ; Cooperative Behavior ; Cultural Evolution ; Exobiology ; Humans ; Language ; Models, Biological ; Models, Theoretical ; Molecular Biology ; Origin of Life ; *Research ; Selection, Genetic
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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    Herve This profile. The joy of evidence-based cooking (2006)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2006-11-25
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Enserink, Martin -- New York, N.Y. -- Science. 2006 Nov 24;314(5803):1235-6.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17124302" target="_blank"〉PubMed〈/a〉
    Keywords: Chemistry ; *Cooking ; *Food ; France ; History, 20th Century ; History, 21st Century
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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    France. Chemist claims innocence to spying charge (2006)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2006-04-29
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Enserink, Martin -- New York, N.Y. -- Science. 2006 Apr 28;312(5773):512.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/16645058" target="_blank"〉PubMed〈/a〉
    Keywords: Chemistry ; China ; *Fatty Acids ; France ; History, 21st Century ; *Theft
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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