ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

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

Proceed reservation?

Export
  • 1
    facet.materialart.
    Unknown
    High-Precision Relative Locations of Two Microearthquake Clusters in Southeastern Sicily, Italy (2007)
    Bulletin of the Seismological Society of America
    Details
    Publication Date: 2017-04-04
    Description: In November 1999 and in January 2000, two microearthquake swarms occurred in Southeastern Sicily (Italy). They were analytically located in the depth range 17-25 km, some kilometers northward from the buried front of a regional foredeep, below the active thrust zone of the Sicily mountain chain. Their hypocentral distribution showed two distinct clusters, and comparison of the waveforms revealed clearly that the two swarms formed two distinct families of multiplet events. This led us: i) to carry out a precise relocation relative to two chosen master events of the families, and ii) to better define the geometrical structure of the two clusters. The cross-spectral method was applied to obtain precise readings of the wave onsets. SH-wave onsets were used instead of P-waves, as they showed clearer onsets and a good signal-to-noise ratio. Residuals of the relative locations showed small values, no more than several meters on average. The vertical extent of the two relocated clusters was 500 m and 250 m, respectively, while the horizontal extent was 250 m. Hypocenters of the first cluster clearly delineate a NNW trending plane with almost vertical dip, matching one nodal plane of the focal mechanism obtained as a composite solution of all events of the cluster. Given the considerable gap angles, because of unfavorable network geometry with respect to the events, the stability of our results was tested carrying out a Montecarlo experiment. Varying the onset times randomly in the range of 5 ms, a dispersion of the locations less than 10 m in longitude, and less than 50 m both in latitude and depth was found. Similar results were obtained when comparing relocations carried out with different master events. Thus, the overall geometrical characteristics of the clusters were not affected seriously by random errors. Considering the geo-structural framework of the region, together with the location and time evolution of the two clusters, fluids of plutonic origin are suggested as the trigger mechanism.
    Description: Published
    Description: 1479–1497
    Description: JCR Journal
    Description: open
    Keywords: earthquake swarms ; cross-correlation ; relative location ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER (OA)
  • 2
    facet.materialart.
    Unknown
    Relocation of microearthquake swarms in the Peloritani mountains – implications on the interpretation of seismotectonic patterns in NE Sicily, Italy (2005)
    Blackwell
    Details
    Publication Date: 2017-04-04
    Description: The Peloritani Mountains in northeastern Sicily make part of the Appennine-Maghrebian Chain, which forms the highly deformed southern margin of the European Continent. In this zone the NW–SE-striking ‘Aeolian-Tindari-Giardini’ System (ATG) separates two areas of seismicity. To the west of the ATG fault system, seismic activity below a depth of 40 km is essentially absent. To the east of this fault system,we note a significant presence of intermediate depth and deep events, which mark the subduction zone in the Calabrian Arc. Between 1994 and 2003 300 microearthquakes could be located with fair accuracy near the ATG fault system. Their depths range from less than 5 to 40 km, with greater depths occurring to the east of the ATG.We examined the resolution capability of the standard location by applying a grid search location for typical events. The distribution of the residuals shows trends recognizable in the standard locations that are in part an artefact of a non-ideal conditions of the standard locations, such as the station configuration, the use of an unsuitable velocity model and inconsistencies of arrival time pickings. By applying relative location techniques (the double-difference method and a master-event technique) we were able to reduce the scatter of hypocentres significantly. We focused in particular on earthquake families with similar waveforms and estimated the geometrical extent of hypocentre clusters. Compared to the standard location the dispersion of hypocentres decreased by an amount of over 90 per cent and the volume occupied by the foci contracted to 1 per cent. The significance of these geometries was tested with Monte Carlo experiments and by interchanging the master events. The cluster geometries are consistent with the dislocation patterns as inferred from fault-plane solutions but do not show a simple relation to the ATG. The role of fluid flow of plutonic origin may be invoked as a possible trigger mechanism. This hypothesis is supported by the presence of geothermal anomalies in the vicinity as well as by an upward migration trend in foci.
    Description: Published
    Description: 225-237
    Description: partially_open
    Keywords: cross-correlation ; earthquake swarms ; focal mechanism ; grid search location ; master-event technique ; relative location ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Format: 538 bytes
    Format: 897721 bytes
    Format: text/html
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER (OA)
  • 3
    facet.materialart.
    Unknown
    High-Precision Relative Locations of Two Microearthquake Clusters in Southeastern Sicily, Italy (2007)
    Seismological Society of America
    Details
    Publication Date: 2017-04-04
    Description: In November 1999 and in January 2000, two microearthquake swarms occurred in Southeastern Sicily (Italy). They were analytically located in the depth range 17-25 km, some kilometers northward from the buried front of a regional foredeep, below the active thrust zone of the Sicily mountain chain. Their hypocentral distribution showed two distinct clusters, and comparison of the waveforms revealed clearly that the two swarms formed two distinct families of multiplet events. This led us: i) to carry out a precise relocation relative to two chosen master events of the families, and ii) to better define the geometrical structure of the two clusters. The cross-spectral method was applied to obtain precise readings of the wave onsets. SH-wave onsets were used instead of P-waves, as they showed clearer onsets and a good signal-to-noise ratio. Residuals of the relative locations showed small values, no more than several meters on average. The vertical extent of the two relocated clusters was 500 m and 250 m, respectively, while the horizontal extent was 250 m. Hypocenters of the first cluster clearly delineate a NNW trending plane with almost vertical dip, matching one nodal plane of the focal mechanism obtained as a composite solution of all events of the cluster. Given the considerable gap angles, because of unfavorable network geometry with respect to the events, the stability of our results was tested carrying out a Montecarlo experiment. Varying the onset times randomly in the range of 5 ms, a dispersion of the locations less than 10 m in longitude, and less than 50 m both in latitude and depth was found. Similar results were obtained when comparing relocations carried out with different master events. Thus, the overall geometrical characteristics of the clusters were not affected seriously by random errors. Considering the geo-structural framework of the region, together with the location and time evolution of the two clusters, fluids of plutonic origin are suggested as the trigger mechanism.
    Description: Published
    Description: 1479–1497
    Description: JCR Journal
    Description: reserved
    Keywords: earthquake swarms ; cross-correlation ; relative location ; master-event technique ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER (OA)
  • 4
    facet.materialart.
    Unknown
    Editorial: Seismicity in Volcanic Areas (2022)
    Frontiers Media S.A.
    Details
    Publication Date: 2022-02-11
    Description: Editorial article
    Description: Seismic activity (e.g., earthquakes, tremors) beneath volcanic areas is primarily caused by the dynamic interaction of molten rock and hydrothermal fluids with the solid host rock, by fracturing and fragmentation of the magma itself, and by tectonic processes interacting with the volcano. In addition, near-surface phenomena such as explosions and rockfalls at a volcanic edifice also produce seismic events. At volcano observatories globally, the real-time monitoring of the spatial and temporal patterns of seismic events is an essential geophysical tool to quantify the state of unrest, and forecast eruptions successfully. Seismic waveforms, earthquake catalogues and earthquake ray-path properties commonly supplement this tool to model the complex processes responsible for the earthquakes quantitatively, and to image subsurface magmatic and tectonic structures. Independent constraints provided by other disciplines such as geodesy and structural geology also significantly help scientists to understand the volcanic processes. Recent advances in earthquake recording technology, computing power and algorithms in artificial intelligence, allow processing and interpretation of large and complex multi-parametric datasets and scenarios.
    Description: Published
    Description: 829460
    Description: 4V. Processi pre-eruttivi
    Description: JCR Journal
    Keywords: earthquake swarms ; volcanic areas ; 04.08. Volcanology ; 04.06. Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER (OA)
  • 5
    Electronic Resource
    Electronic Resource
    The relationship between earthquake swarms and magma transport: Kilauea volcano, Hawaii (1987)
    Springer
    Pure and applied geophysics 125 (1987), S. 971-991 
    Details
    ISSN: 1420-9136
    Keywords: Kilauea volcano ; earthquake swarms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A detailed investigation of earthquake locations and focal mechanisms for swarms associated with intrusive events at Kilauea volcano, Hawaii, further illuminates the relationships among stress state, faulting, and magma transport. We determine the earthquake locations and mechanisms using a three-dimensional crustal model to improve their accuracy and consistency. Swarms in Kilauea's upper east and southwest rift zones, from the years 1980 through 1982, provide clear evidence for the propagation and/or dilation of dikes. Focal mechanisms are predominantly strike-slip, and the faulting and inferred dike orientations can be interpreted quite consistently in terms of the model ofHill (1977). Stresses induced by the summit magma reservoir system strongly control faulting and magma transport in the rift zones close to the summit.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00879363
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Analysis of State of Stress During The 1997 Earthquake Swarm In Western Bohemia (2000)
    Springer
    Studia geophysica et geodaetica 44 (2000), S. 272-291 
    Details
    ISSN: 1573-1626
    Keywords: West Bohemia ; earthquake swarms ; stress analysis ; Gephart and Forsyth method ; fault plane discrimination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences , Physics
    Notes: Abstract Focal mechanisms of 70 events of the January 1997 earthquake swarm were analysed using the Gephart and Forsyth method to determine the state of stress in the West Bohemia/Vogtland region and to reveal possible stress variations during the swarm activity. The method was applied to the whole set of 70 focal mechanisms and to several subsets distinguishing magnitudes of events and the spatial and temporal distribution of the swarm. The three representative stress models A (σ 1 ,A: 0/45 (az/dip), σ 2 A: 134/35, σ 3 A: 243/25), B (σ 1 ,B: 162/38, σ 2 B: 263/14, σ 3 B: 10/49), and C (σ 1 C: 135/30, σ 2 C: 1/50, σ 3 C: 239/23) which could characterise the state of stress in the region were found. Model C can be considered to be the most probable stress model because of its consistency with the European stress field. The results of the stress analysis applied to the individual subsets of focal mechanisms indicate that the state of stress was more uniform during the first phase of the swarm. To distinguish between the fault plane and the auxiliary plane of fault plane solutions a statistical approach was used. The results showed that the fault planes striking NW-SE and dipping 45° to NE were activated during the swarm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022171027896
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Subsurface Temperature Changes Due to the Crustal Magmatic Activity – Numerical Simulation (2000)
    Springer
    Studia geophysica et geodaetica 44 (2000), S. 327-335 
    Details
    ISSN: 1573-1626
    Keywords: magma intrusions ; crustal temperatures ; earthquake swarms ; Bohemian Massif
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences , Physics
    Notes: Abstract Geothermal aspects of the hypothesis, relating the earthquake swarms in the West Bohemia/Vogtland seismoactive region to magmatic activity, are addressed. A simple 1-D geothermal model of the crust was used to assess the upper limit of the subsurface heating caused by magma intrusion at the assumed focal depth of 9 km. We simulated the process by solving the transient heat conduction equation numerically, considering the heat of magma crystallization to be gradually released in the temperature interval 1100°C to 900°C. The temperature field prior to the intrusion was in steady-state with a surface temperature of 10°C and heat flow of 80 mWm −2 , the temperature at the 9 km depth was 270°C. The results suggest that the temperature and heat flow in the uppermost 1 km of the crust begin to grow 100 ka after the intrusion emplacement only, and that the amplitudes of the changes for the realistic lateral extent (a few kilometres) of the intrusion are very small. It was also found that the rate of magma solidification depends strongly on the thickness of the intrusion. It takes about 100 years for a 50 m thick sill to cool down from 1100°C to 600°C, which value represents the lower limit of the solidus temperature. The same cooling takes only 60 days if the sill is 2 m thick. If the nature of the strongly reflected boundaries, interpreted from the January 1997 Nový Kostel seismograms, is connected with the fresh emplacement of magma, the calculated cooling rates have a predictive potential for the temporal changes of the waveforms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022127312875
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Magma Intrusions and Earthquake Swarm Occurrence in the Western Part of the Bohemian Massif (1999)
    Springer
    Studia geophysica et geodaetica 43 (1999), S. 87-106 
    Details
    ISSN: 1573-1626
    Keywords: earthquake swarms ; magma intrusions ; fluids ; Bohemian Massif ; induced seismicity ; WEBNET ; KTB ; 9HR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences , Physics
    Notes: Abstract We are proposing a hypothesis that earthquake swarms in the West Bohemia/Vogtland seismoactive region are generated by magmatic activity currently transported to the upper crustal layers. We assume that the injection of magma and/or related fluids and gases causes hydraulic fracturing which is manifested as an earthquake swarm at the surface. Our statements are supported by three spheres of evidence coming from the western part of the Bohemian Massif: characteristic manifestations of recent geodynamic activity, the information from the neighbouring KTB deep drilling project and from the 9HR seismic reflection profile, and the detailed analysis of local seismological data. (1) Recent manifestations of geodynamic activity include Quaternary volcanism, rich CO 2 emissions, anomalies of mantle-derived 3 He, mineral springs, moffets, etc. (2) The fluid injection experiment in the neighbouring KTB deep borehole at a depth of 9 km induced hundreds of micro-earthquakes. This indicates that the Earth's crust is near frictional failure in the western part of the Bohemian Massif and an addition of a small amount of energy to the tectonic stress is enough to induce an earthquake. Some pronounced reflections in the closely passing 9HR seismic reflection profile are interpreted as being caused by recent magmatic sills in the crust. (3) The local broadband seismological network WEBNET provides high quality data that enable precise localization of seismic events. The events of the January 1997 earthquake swarm are confined to an extremely narrow volume at depths of about 9 km. Their seismograms display pronounced reflections of P- and S-waves in the upper crust. The analysis of the process of faulting has disclosed a considerable variability of the source mechanism during the swarm. We conclude that the mechanism of intraplate earthquake swarms generated by magma intrusions is similar to that of induced seismicity. As the recent tectonic processes and manifestations of geodynamic activity are similar in European areas with repeated earthquake swarm occurrence (Bohemian Massif, French Massif Central, Rhine Graben), we assume that magma intrusions and related fluid and gas release at depths of about 10 km are the universal cause of intraplate earthquake swarm generation
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1023366210017
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    The Western Bohemia/Vogtland Region in the Light of the Webnet Network (2000)
    Springer
    Studia geophysica et geodaetica 44 (2000), S. 107-125 
    Details
    ISSN: 1573-1626
    Keywords: West Bohemia ; earthquake swarms ; local seismic network ; local magnitude ; local earthquake waveform
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences , Physics
    Notes: Abstract The local network of digital seismic stations WEBNET monitors the seismic activitv of practically the whole region of Western Bohemia/Vogtland swarms. The network consists of ten short-period stations and one very broadband station. The paper describes the configuration of the network, instrumental equipment and the basic parameters of the stations. The method of and formula for computing the local magnitudes from the WEBNET and KRASLICE seismograms are also given. Based on continuous WEBNET observations in the period 1995-1999, we were able to improve the model of temporal and spatial energy release in the region, the principal characteristics of which are summarised in the paper. Apart from direct P and S waves, the WEBNET seismograms also contain other significant P- and S-type waves, provisionally interpreted as reflected PxP, SxS and SxP waves. The fundamental characteristics of these waves are given in the paper, and tentative mechanisms of their origination are discussed. The large residua in the travel times of the P and S waves, and the discrepancies in the seismograms recorded at stations located east of the principal focal zone are pointed out.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022198406514
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Refined Locations of The Swarm Earthquakes In The Nový Kostel Focal Zone and Spatial Distribution of The January 1997 Swarm In Western Bohemia, Czech Republic (2000)
    Springer
    Studia geophysica et geodaetica 44 (2000), S. 210-226 
    Details
    ISSN: 1573-1626
    Keywords: earthquake swarms ; cluster of foci ; relative location ; cluster analysis ; multiplet events
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences , Physics
    Notes: Abstract In order to improve the accuracy of the spatial distribution of earthquake foci in the principal Novy Kostel focal zone, refined focal locations of about 1500 micro-earthquakes of the 1991 – 1997 period were determined using the relative Master-Event location method. To estimate the reduction in the scatter of located hypocentres, the results were compared with those obtained by routinely used FASTHYPO method and cluster analysis (the nearest-neighbour method) was applied to the located foci to evaluate the spatial distribution of the foci. Based on the results of refined location and of the cluster analysis, a concept of seismic energy release in space and time in the main focal zone was developed. Especially the January 1997 earthquake swarm was studied in detail: 946 events were located with the Master-Event location method, and the dimensions and geometry of focal clusters were determined. Type analysis was applied to waveforms to divide approximately 800 located events into eight multiplet groups to each of which a characteristic source mechanism was assigned. The spatial distribution of the foci as well as of the eight types of source mechanisms was revealed in this way and also the planes fitting the clusters of foci with two predominant source mechanisms were determined fairly well.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022162826079
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...