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  • 1
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    Relocation of Earthquakes by Source-Specific Station Corrections in Iran (2015)
    Seismological Society of America (SSA)
    Details
    Publikationsdatum: 2015-10-02
    Beschreibung: Accurate earthquake locations are crucial for investigating seismogenic processes, as well as for applications like verifying compliance to the Comprehensive Nuclear-Test-Ban Treaty. Modeling errors of calculated travel times, in addition to the density of the stations, their epicentral distances, and their azimuthal coverage, may have the effect of shifting the computed epicenters far from the real locations, regardless of the accuracy in picking seismic phase arrivals. In the present study, we compare the regional locations for one set of earthquakes obtained by arrival times reported by the Iranian Seismological Center with teleseismic locations obtained by arrival times reported by the International Seismological Center. We found location differences on the order of 10–20 km or larger, affecting both epicentral coordinates and depths. Average travel-time residuals to each station of the global network were computed for a set of sources located in the study area. We show that systematic shifts of hypocentral coordinates, as well as the sizes of their error ellipses, can be substantially reduced by applying source-specific station corrections. Finally, the validity of the calibration method was confirmed by a test carried out on a dataset different from that used for computing the travel-time corrections. This study includes an analysis of the effect of removing arrival times of critical stations from the dataset used for the locations, showing that this effect is largely reduced by the application of travel-time corrections. Online Material: Tables of hypocentral parameters with related information, stations used for relocation, and parameters computed for the teleseismic analysis.
    Print ISSN: 0037-1106
    Digitale ISSN: 1943-3573
    Thema: Geologie und Paläontologie , Physik
    Publiziert von Seismological Society of America (SSA)
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    PAPER CURRENT
  • 2
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    Unbekannt
    UN SISTEMA DI ACQUISIZIONE E CONDIVISIONE DEI DATI SISMICI TRA L’INTERNATIONAL MONITORING SYSTEM DEL CTBTO E LA RETE NAZIONALE CENTRALIZZATA DELL’INGV (2007)
    Istituto Nazionale di Geofisica e Vulcanologia
    Details
    Publikationsdatum: 2017-04-03
    Beschreibung: UN SISTEMA DI ACQUISIZIONE E CONDIVISIONE DEI DATI SISMICI TRA L’INTERNATIONAL MONITORING SYSTEM DEL CTBTO E LA RETE NAZIONALE CENTRALIZZATA DELL’INGV
    Beschreibung: Published
    Beschreibung: 19
    Beschreibung: 5.5. Consulenze e attività in favore di istituzioni nazionali
    Beschreibung: N/A or not JCR
    Beschreibung: open
    Schlagwort(e): IMS CTBTO ; INGV VAE ; 05. General::05.01. Computational geophysics::05.01.01. Data processing
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    ARTIKEL (OA)
  • 3
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    Unbekannt
    Le Sorgenti sismiche: teoria ed osservazioni (2008)
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Scopo di questo lavoro è quello di fornire al lettore (più o meno esperto) uno strumento per la comprensione (concettuale ed analitica) di alcuni aspetti della teoria dinamica dell’elasticità, passando poi alla rappresentazione delle sorgenti sismiche, alla loro radiazione ed alla determinazione del loro meccanismo. Il terremoto infatti, non è altro che l’effetto delle onde sismiche, cioè il processo di oscillazione della Terra e, in particolare, della superficie terrestre, dove tale oscillazione è osservabile. La sorgente del terremoto (o sorgente sismica) è la sorgente delle onde sismiche. Nel capitolo 1 si fa riferimento in particolare al più semplice problema dinamico per un mezzo isotropo; la sorgente sismica infatti è forza impulsiva applicata ad un solo punto e orientata come uno degli assi del sistema di riferimento. E’ stata descritta la relazione che rappresenta la radiazione emessa da tali sorgenti in un mezzo elastico illimitato, omogeneo ed isotropo fino ad arrivare alla soluzione rappresentata dal Tensore di Green. Successivamente, (capitolo 2), viene fornita una descrizione sulla rappresentazione delle sorgenti sismiche sia in modo analitico che concettuale. Anche in questo caso è fatta una trattazione completa del problema, per poi giungere alla definizione di tensore momento sismico. Il terzo capitolo riguarda invece la trattazione sulla radiazione della sorgente sismica, sul campo degli spostamenti e sulle funzioni di irraggiamento, partendo dai risultati del primo e del secondo capitolo. Infine nella quarta ed ultima parte si è descritto il meccanismo focale di frattura, funzioni di irraggiamento per una frattura (orientata secondo gli assi o arbitrariamente) descrivendo la sfera focale e le sue proiezioni ed alcuni metodi per la determinazione del meccanismo focale.
    Beschreibung: Istituto Nazionale di Geofisica e Vulcanologia
    Beschreibung: Published
    Beschreibung: 3.1. Fisica dei terremoti
    Beschreibung: 5.6. Consulenze in favore di istituzioni nazionali e attività nell'ambito di trattati internazionali
    Beschreibung: open
    Schlagwort(e): sorgenti sismiche ; elastodinamica ; meccanismi focali di frattura ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: report
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    ARTIKEL (OA)
  • 4
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    Station Travel‐Time Calibration Method Improves Location Accuracy on a Global Scale (2015)
    Seismological Society of America
    Details
    Publikationsdatum: 2020-02-24
    Beschreibung: Accurate earthquake locations are crucial for investigating seismogenic processes, as well as for applications like verifying compliance to the Comprehensive Test Ban Treaty. Earthquake location accuracy is related to the degree of knowledge about the 3-D structure of seismic wave velocity in the Earth. It is well known that modeling errors of calculated travel times may have the effect of shifting the computed epicenters far from the real locations by a distance even larger than the size of the statistical error ellipses, regardless of the accuracy in picking seismic phase arrivals. In the present study, we develop a method of seismic location based on a set of well located events recorded by the dense national seismic network in a seismically active region of central Japan. We show that mislocations of the order of 10-20 km affecting the epicenters calculated from a global seismic network and using the standard IASPEI91 travel times can be effectively removed by applying station-source-specific corrections. The results show a clear correlation of the travel time residuals with the subduction structure beneath Japan.
    Beschreibung: Published
    Beschreibung: 225-236
    Beschreibung: 2T. Tettonica attiva
    Beschreibung: JCR Journal
    Beschreibung: restricted
    Schlagwort(e): Travel-time correction ; Teleseimic location ; Seismic monitoring and test-ban treaty verification. ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    ARTIKEL (OA)
  • 5
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    A Multidisciplinary Study of the DPRK Nuclear Tests (2013)
    Springer Verlag
    Details
    Publikationsdatum: 2020-02-24
    Beschreibung: The Democratic People Republic of Korea announced two underground nuclear tests carried out in their territory respectively on October 9th, 2006 and May 25th, 2009. The scarce information on the precise location and the size of those explosions has stimulated various kinds of studies,mostly based on seismological observations, by several national agencies concerned with theNuclear Test Ban Treaty verification.Weanalysed the available seismological data collected through a global high-quality network for the two tests. After picking up the arrival times at the various stations, a standard location program has been applied to the observed data. If we use all the available data for each single event, due to the different magnitude and different number of available stations, the locations appear quite different. On the contrary, if we use only the common stations, they happen to be only few km apart from each other and within their respective error ellipses. A more accurate relative location has been carried out by the application of algorithms such as double difference joint hypocenter determination (DDJHD) and waveform alignment. The epicentral distance between the two events obtained by these methods is 2 km, with the 2006 event shifted to the ESE with respect to that of 2009. We then used a dataset of VHR TerraSAR-X satellite images to detect possible surface effects of the underground tests. This is the first ever case where these highly performing SAR data have been used to such aim. We applied InSAR processing technique to fully exploit the capabilities of SAR data to measure very short displacements over large areas. Two interferograms have been computed, one co-event and one post-event, to remove possible residual topographic signals. A clear displacement pattern has been highlighted over a mountainous area within the investigated region, measuring a maximum displacement of about 45 mm overall the relief. Hypothesizing that the 2009 nuclear test had been carried out close to the area where the displacement has been observed through the DInSAR technique, its relation with the epicenter location obtained through seismological processing has been discussed as a possible alternative hypothesis with respect to the preferred solutions reported by the nuclear explosion database (NEDB). The distance of about 10 km between the two places can be considered acceptable in light of the possible systematic location shifts commonly observed in the seismological practice over a global scale. The difference between the mb magnitudes of the two tests could reflect differences in geological conditions of the two test sites, even if the yield of the two explosions had been the same.
    Beschreibung: Published
    Beschreibung: 341-359
    Beschreibung: JCR Journal
    Beschreibung: restricted
    Schlagwort(e): underground nuclear test ; Double Difference Joint Hypocenter Determination DDJHD ; waveform alignment ; SAR data ; InSAR technique ; 04. Solid Earth::04.03. Geodesy::04.03.06. Measurements and monitoring ; 04. Solid Earth::04.03. Geodesy::04.03.07. Satellite geodesy ; 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::05.01.01. Data processing ; 05. General::05.01. Computational geophysics::05.01.03. Inverse methods ; 05. General::05.01. Computational geophysics::05.01.05. Algorithms and implementation
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    ARTIKEL (OA)
  • 6
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    Unbekannt
    High resolution aeromagnetic anomaly map of Mount Etna volcano, Southern Italy (2014)
    Elsevier Science Limited
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: A high resolution aeromagnetic survey of Mount Etna Volcano was carried out by the Airborne Geophysics Science Team of Istituto Nazionale di Geofisica e Vulcanologia (INGV), aimed at producing the most detailed magnetic anomaly map existing so far for this area. Two datasets of the total intensity of the Earth's Magnetic Field were collected at different altitudes to take into account the huge topographic variations of Etna volcano, that reaches elevations above 3300 m asl. One level was flown at the altitude of 2200 m whereas a second one over the central part, at about 3500 m of altitude. Since the region is characterized by a large presence of strongly magnetized volcanic products, the survey was carried out acquiring profile lines only, in order to optimize the resources. From the residual magnetic anomaly analysis we inferred two main trending lineaments (− 35°N and 0°N) that are related to regional tectonic stress field and we interpret the main magnetic anomaly as the effect of thickness variation of magnetized volcanic products due to the complex pre-volcanic basement morphology of Etna.
    Beschreibung: Published
    Beschreibung: 36-40
    Beschreibung: 7A. Geofisica di esplorazione
    Beschreibung: JCR Journal
    Beschreibung: restricted
    Schlagwort(e): Etna volcano ; Magnetic anomalies ; Aeromagnetism ; potential fields ; Fry analysis ; 04. Solid Earth::04.05. Geomagnetism::04.05.04. Magnetic anomalies
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    ARTIKEL (OA)
  • 7
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    Unbekannt
    Early stage sinkhole formation in the acque albule basin of central Italy from geophysical and geochemical observations (2015)
    Springer Berlin Heidelberg
    Details
    Publikationsdatum: 2021-12-16
    Beschreibung: Sinkhole occurrence along the Tyrrhenian margin of the Central Apennines is of great importance for applied research, land management and civil protection. This study reports on GPS-altimetry magnetic, gravity, geoelectric, seismic, and soil gas measurements of a rapidly developing sinkhole near the Guidonia military airport. The measurements revealed an elliptical 2-m depression elongated 220 m in the NNE-SSW direction with the minor axis of 110 m. In spring of 2013, two vertical cavities formed in the eastern and northeastern flanks of the depression whose depths and shapes are rapidly evolving with the formation of widespread fracturing along the same side. The geophysical observations image the developing sinkhole to a depth of some 50 m, the presence of the Travertino lithotype around the depression (down to at least 40 m), and the lack of this lithotype below the lowered area. The sinkhole's evolution appears to be structurally controlled by local and regional faulting. These results are useful for designing further geophysical, geotechnical and geochemical studies to monitor the sinkhole's evolution and to assess the hazard it presents in densely urbanized area.
    Beschreibung: Published
    Beschreibung: 36-47
    Beschreibung: 7A. Geofisica di esplorazione
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Acque Albule basin, sinkholes, subsidence, geophysical prospecting ; 04. Solid Earth::04.02. Exploration geophysics::04.02.99. General or miscellaneous ; 04. Solid Earth::04.02. Exploration geophysics::04.02.01. Geochemical exploration ; 04. Solid Earth::04.02. Exploration geophysics::04.02.02. Gravity methods ; 04. Solid Earth::04.02. Exploration geophysics::04.02.04. Magnetic and electrical methods ; 04. Solid Earth::04.02. Exploration geophysics::04.02.06. Seismic methods ; 04. Solid Earth::04.02. Exploration geophysics::04.02.07. Instruments and techniques
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    ARTIKEL (OA)
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