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| Titel |
Similarity and Cluster Analysis of Intermediate Deep Events in the Southeastern Aegean |
| VerfasserIn |
Marija Ruscic, Dirk Becker, Andrea Brüstle, Thomas Meier |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250151489
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| Publikation (Nr.) |
 EGU/EGU2017-16078.pdf |
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| Zusammenfassung |
| We analyze a cluster of intermediate deep events in the eastern part of the Hellenic subduction zone (HSZ), recorded during the the deployment of the temporary seismic network EGELADOS in order to gain a better understanding of geodynamic processes in the HSZ, in particular in the eastern part. The cluster consists of 159 events at 80 to 200 km depth with local magnitudes ranging from magnitude 0.2 to magnitude 4.1.
By using the three component similarity analysis, both spatial and temporal clustering of the recorded events is studied. The waveform cross-correlation was performed for all event combinations using data recorded on 45 onshore stations. The cross-correlation coefficients at the single stations show a decrease in similarity with increasing epicentral distance as well as the effect of local heterogenities at particular stations, causing noticable differences in waveform similarities. However, highly similar events tend to happen at the prefered depth ranges between 120 to 150 km depth. The double-difference earthquake relocation software HypoDD was used to perform the event relocation. The results are compared with previously obtained single event locations which were calculated using nonlinear location tool NonLinLoc and station corrections. For the relocation, both differential traveltimes obtained by separate cross-correlation of P- and S-waveforms and manual readings of onset times are used. It is shown that after the relocation the inter-event distance for highly similar events has been reduced. By comparing the results of the cluster analysis with results obtained from the synthetic catalogs, where the event rate, number of aftershocks and occurrence time of the aftershocks is varied, it is shown that the event-time distribution follows almost a random Poisson time distribution with a slightly increasing event rate without indications for substantial inter-event triggering. The spatial distribution of the cluster can be modelled by a two-dimensional Gaussian distribution on a plane parallel to the subduction interface with standard deviations of less than 15 km where the most likely inter-event distance is about 20 km. These properties of the intermediate deep seismicity at a preferred depth range within an about 30 km by 50 km width zone point to fluid release at those depths and not to triggering by fluid migration. |
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